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Concept: Calcium channel

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Evidence is accumulating that commonly used pesticides are linked to decline of pollinator populations; adverse effects of three neonicotinoids on bees have led to bans on their use across the European Union. Developing insecticides that pose negligible risks to beneficial organisms such as honeybees is desirable and timely. One strategy is to use recombinant fusion proteins containing neuroactive peptides/proteins linked to a ‘carrier’ protein that confers oral toxicity. Hv1a/GNA (Galanthus nivalis agglutinin), containing an insect-specific spider venom calcium channel blocker (ω-hexatoxin-Hv1a) linked to snowdrop lectin (GNA) as a ‘carrier’, is an effective oral biopesticide towards various insect pests. Effects of Hv1a/GNA towards a non-target species, Apis mellifera, were assessed through a thorough early-tier risk assessment. Following feeding, honeybees internalized Hv1a/GNA, which reached the brain within 1 h after exposure. However, survival was only slightly affected by ingestion (LD50>100 µg bee(-1)) or injection of fusion protein. Bees fed acute (100 µg bee(-1)) or chronic (0.35 mg ml(-1)) doses of Hv1a/GNA and trained in an olfactory learning task had similar rates of learning and memory to no-pesticide controls. Larvae were unaffected, being able to degrade Hv1a/GNA. These tests suggest that Hv1a/GNA is unlikely to cause detrimental effects on honeybees, indicating that atracotoxins targeting calcium channels are potential alternatives to conventional pesticides.

Concepts: Protein, Insect, Arthropod, Honey bee, Fusion protein, Calcium channel blocker, Calcium channel, Galanthus

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L-type calcium channels expressed in the brain are heterogeneous. The predominant class of L-type calcium channels has a Ca(V)1.2 pore-forming subunit. L-type calcium channels with a Ca(V)1.3 pore-forming subunit are much less abundant, but have been implicated in the generation of mitochondrial oxidant stress underlying pathogenesis in Parkinson’s disease. Thus, selectively antagonizing Ca(V)1.3 L-type calcium channels could provide a means of diminishing cell loss in Parkinson’s disease without producing side effects accompanying general antagonism of L-type calcium channels. However, there are no known selective antagonists of Ca(V)1.3 L-type calcium channel. Here we report high-throughput screening of commercial and ‘in-house’ chemical libraries and modification of promising hits. Pyrimidine-2,4,6-triones were identified as a potential scaffold; structure-activity relationship-based modification of this scaffold led to 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (8), a potent and highly selective Ca(V)1.3 L-type calcium channel antagonist. The biological relevance was confirmed by whole-cell patch-clamp electrophysiology. These studies describe the first highly selective Ca(V)1.3 L-type calcium channel antagonist and point to a novel therapeutic strategy for Parkinson’s disease.

Concepts: Medicine, Ion channel, Electrophysiology, Ion channels, Calcium channel blocker, Voltage-dependent calcium channel, Calcium channel

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Abstract BACKGROUND: Vascular dementia (VaD) - a severe form of vascular cognitive impairment - and cognitive decline are associated with hypertension and therefore it seems logical to consider that reducing BP with anti-hypertensive therapy may protect against the development/onset of cognitive function impairment or dementia. SCOPE: This narrative, non-systematic review discusses the available evidence on the potential correlation between the use of anti-hypertensive agents and the risk of VaD and cognitive decline. METHODS: MEDLINE was searched for inclusion of relevant studies. No limitations in time were considered. RESULTS: A consensus on the potential effects of anti-hypertensive treatment in the reduction of VaD and associated cognitive decline has not been reached. A protective effect of anti-hypertensive agents has been observed in a number of studies although it is still unclear if different classes of anti-hypertensive agents have a different effect on the development of VaD. CONCLUSIONS: The protective effect of anti-hypertensive agents appears to depend on the specific drug used - positive effects have been observed with calcium channel blockers (CCBs), such as lercanidipine and nitrenidipine, the combination perindopril-indapamide and telmisartan.

Concepts: Hypertension, Effect, Cognition, Knowledge, Reasoning, Calcium channel blocker, Calcium channel, Binswanger's disease

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Exposure to lead (Pb) can induce kidney damage, which is related to induction of oxidative damage and disturbance of intracellular calcium homeostasis. Pb can readily permeate through dihydropyridine-sensitive L-type calcium channels and accumulate within cells. The objective of this study was to investigate protective effects of calcium channel blockers (CCBs) verapamil and nimodipine on nephrotoxicity induced by Pb acetate in mice. One hundred twenty male mice were randomly divided into 6 groups: control, Pb, low-dose verapamil, high-dose verapamil, low-dose nimodipine and high-dose nimodipine (n=20 per group). Pb acetate was injected intraperitoneally (i.p.) at 40mg/kg body weight/day for 10 days to establish the Pb toxicity model. While control mice received saline, mice of the treated groups simultaneously received i.p. injections of verapamil or nimodipine daily for 10 days. Both verapamil and nimodipine showed protection against Pb-induced kidney injury, including alleviation of renal pathological damage and decreasing the level of Pb in kidney homogenate and extent of apoptosis in nephrocytes. Moreover, verapamil and nimodipine significantly down-regulated levels of blood urea nitrogen and creatinine in the serum. In addition, verapamil and nimodipine administration decreased malondialdehyde content and increased activities of super oxide dismutase activity and glutathione peroxidase in the kidney homogenate. The findings in the present study implicate the therapeutic potential of CCBs for Pb-induced nephrotoxicity, which were at least partly due to the decrease of Pb uptake and inhibition of lipid peroxidation.

Concepts: Kidney, Nephrology, Antioxidant, Oxidative stress, Reactive oxygen species, Blood urea nitrogen, Calcium channel blocker, Calcium channel

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The ryanodine receptor (RyR) family of calcium release channels plays a vital role in excitation-contraction coupling (ECC). Along with the dihydropyridine receptor (DHPR), calsequestrin, and several other smaller regulatory and adaptor proteins, RyRs form a large dynamic complex referred to as ECC machinery. Here we describe a simple cross-linking procedure that can be used to stabilize fragile components of the ECC machinery, for the purpose of structural elucidation by single particle cryo-electron microscopy (cryo-EM). As a model system, the complex of the FK506-binding protein (FKBP12) and RyR1 was used to test the cross-linking protocol. Glutaraldehyde fixation led to complete cross-linking of receptor-bound FKBP12 to RyR1, and also to extensive cross-linking of the four subunits comprising RyR to one another without compromising the RyR1 ultrastructure. FKBP12 cross-linked with RyR1 was visualized in 2D averages by single particle cryo-EM. Comparison of control RyR1 and cross-linked RyR1 3D reconstructions revealed minor conformational changes at the transmembrane assembly and at the cytoplasmic region. Intersubunit cross-linking enhanced [(3)H]ryanodine binding to RyR1. Based on our findings we propose that intersubunit cross-linking of RyR1 by glutaraldehyde induced RyR1 to adopt an open like conformation.

Concepts: Protein, Protein structure, Cell membrane, Receptor, Ryanodine receptor, Ryanodine, Calcium channel, RYR1

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To provide a management approach for adults with calcium channel blocker poisoning.

Concepts: Calcium channel blocker, Calcium channel

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The progress in instrumentation technology has led to miniaturization of NIR instruments. Fast systems that contain no moving parts were developed to be used in the field, warehouses, drugstores, etc. At the same time, in general these portable/handheld spectrometers have a lower spectral resolution and a narrower spectral region than stationary ones. Vendors of portable instruments supply their equipment with special software for spectra processing, which aims at simplifying the analyst’s work to the highest degree possible. Often such software is not fully capable of solving complex problems. In application to a real-world problem of counterfeit drug detection we demonstrate that even impaired spectral data do carry information sufficient for drug authentication. The chemometrics aided approach helps to extract this information and thus to extend the applicability of miniaturized NIR instruments. MicroPhazir-RX NIR spectrometer is used as an example of a portable instrument. The data driven soft independent modeling of class analogy (DD-SIMCA) method is employed for data processing. A representative set of tablets of a calcium channel blocker from 6 different manufacturers is used to illustrate the proposed approach. It is shown that the DD-SIMCA approach yields a better result than the basic method provided by the instrument vendor.

Concepts: Problem solving, Object-oriented programming, Calcium channel, Instrument, Miniature helicopter, Authentication, The Analyst, Instruments

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Genetic variations in CACNA1C, which encodes the Cav1.2 subunit of L-type calcium channels (LTCCs), are associated with multiple forms of neuropsychiatric disease that manifest high anxiety in patients. In parallel, mice harboring forebrain-specific conditional knockout of cacna1c (forebrain-Cav1.2 cKO) display unusually high anxiety-like behavior. LTCCs in general, including the Cav1.3 subunit, have been shown to mediate differentiation of neural precursor cells (NPCs). However, it has not previously been determined whether Cav1.2 affects postnatal hippocampal neurogenesis in vivo. Here, we show that forebrain-Cav1.2 cKO mice exhibit enhanced cell death of young hippocampal neurons, with no change in NPC proliferation, hippocampal size, dentate gyrus thickness, or corticosterone levels compared with wild-type littermates. These mice also exhibit deficits in brain levels of brain-derived neurotrophic factor (BDNF), and Cre recombinase-mediated knockdown of adult hippocampal Cav1.2 recapitulates the deficit in young hippocampal neurons survival. Treatment of forebrain-Cav1.2 cKO mice with the neuroprotective agent P7C3-A20 restored the net magnitude of postnatal hippocampal neurogenesis to wild-type levels without ameliorating their deficit in BDNF expression. The role of Cav1.2 in young hippocampal neurons survival may provide new approaches for understanding and treating neuropsychiatric disease associated with aberrations in CACNA1C. Visual Abstract.

Concepts: Gene, Dentate gyrus, Neurogenesis, Ion channels, Neurotrophin, Brain-derived neurotrophic factor, Voltage-dependent calcium channel, Calcium channel

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Mounting in vitro, in vivo and clinical evidence suggest an important role for filopodia in driving cancer cell invasion. Using a high-throughput microscopic-based drug screen, we identify FDA-approved calcium channel blockers (CCBs) as potent inhibitors of filopodia formation in cancer cells. Unexpectedly, we discover that L-type calcium channels are functional and frequently expressed in cancer cells suggesting a previously unappreciated role for these channels during tumorigenesis. We further demonstrate that, at filopodia, L-type calcium channels are activated by integrin inside-out signalling, integrin activation and Src. Moreover, L-type calcium channels promote filopodia stability and maturation into talin-rich adhesions through the spatially restricted regulation of calcium entry and subsequent activation of the protease calpain-1. Altogether we uncover a novel and clinically relevant signalling pathway that regulates filopodia formation in cancer cells and propose that cycles of filopodia stabilization, followed by maturation into focal adhesions, directs cancer cell migration and invasion.

Concepts: Gene expression, Cancer, Cell division, Cell biology, Tyrosine kinase, DNA replication, Calcium channel blocker, Calcium channel