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The mutated form of the Ca2+ channel CALHM1 (Ca2+ homeostasis modulator 1), P86L-CALHM1, has been correlated with early onset of Alzheimer's disease (AD). P86L-CALHM1 increases production of amyloid beta (Aά) upon extracellular Ca2+ removal and its subsequent addback. The aim of this study was to investigate the effect of the overexpression of CALHM1 and P86L-CALHM, upon Aά treatment, on the following: (i) the intracellular Ca2+ signal pathway; (ii) cell survival proteins ERK1/2 and Ca2+/cAMP response element binding (CREB); and (iii) cell vulnerability after treatment with Aά. Using aequorins to measure the effect of nuclear Ca2+ concentrations ([Ca2+]n) and cytosolic Ca2+ concentrations ([Ca2+]c) on Ca2+ entry conditions, we observed that baseline [Ca2+]n was higher in CALHM1 and P86L-CALHM1 cells than in control cells. Moreover, exposure to Aά affected [Ca2+]c levels in HeLa cells overexpressing CALHM1 and P86L-CALHM1 compared with control cells. Treatment with Aά elicited a significant decrease in the cell survival proteins p-ERK and p-CREB, an increase in the activity of caspases 3 and 7, and more frequent cell death by inducing early apoptosis in P86L-CALHM1- overexpressing cells than in CALHM1 or control cells. These results suggest that in the presence of Aά, P86L-CALHM1 shifts the balance between neurodegeneration and neuronal survival toward the stimulation of pro-cytotoxic pathways, thus potentially contributing to its deleterious effects in AD. [ABSTRACT FROM AUTHOR]

ABSTRACT We have developed a method of liquid chromatography in tandem with mass spectrometry to monitor therapeutic levels of imatinib in plasma, a selective inhibitor of protein tyrosine kinase. After solid-phase extraction of plasma samples, imatinib and its internal standard, imatinib-D8, were eluted with Zorbax SB-C18 at 60 °C, under isocratic conditions through a mobile phase consisting of 4 m m ammonium formate, pH: 3.2 (solution A) and acetonitrile solution B. The flow rate was 0.8 mL/min with 55% solution A + 45% solution B. Imatinib was detected and quantified by mass spectrometry with electrospray ionization operating in selected-reaction monitoring mode. The calibration curve was linear in the range 10-5000 ng/mL, the lower limit of quantitation being 10 ng/mL. The method was validated according to the recommendations of the Food and Drug Administration, including tests of matrix effect (bias < 10%) and recovery efficiency (>80 and <120%). The method is precise (coefficient of variance intra-day <2% and inter-day <7%), accurate (95-108%), sensitive and specific. It is a simple method with very fast recording time (1.2 min) that is applicable to clinical practice. This will permit improvement of the pharmacological treatment of patients. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary: Altered calcium homeostasis and increased cytosolic calcium concentrations ([Ca2+]c) are linked to neuronal apoptosis in epilepsy and in cerebral ischemia, respectively. Apoptotic programmed cell death is regulated by the antiapoptotic Bcl2 family of proteins. Here, we investigated the role of Bcl2 on calcium (Ca2+) homeostasis in PC12 cells, focusing on L-type voltage-dependent calcium channels (VDCC). Cytosolic Ca2+ transients ([Ca2+]c) and changes of mitochondrial Ca2+ concentrations ([Ca2+]m) were monitored using cytosolic and mitochondrially targeted aequorins of control PC12 cells and PC12 cells stably overexpressing Bcl2. We found that: (i) the [Ca2+]c and [Ca2+]m elevations elicited by K+ pulses were markedly depressed in Bcl2 cells, with respect to control cells; (ii) such depression of [Ca2+]m was not seen either in digitonin-permeabilized cells or in intact cells treated with ionomycin; (iii) the [Ca2+]c transient depression seen in Bcl2 cells was reversed by shRNA transfection, as well as by the Bcl2 inhibitor HA14-1; (iv) the L-type Ca2+ channel agonist Bay K 8644 enhanced K+-evoked [Ca2+]m peak fourfold in Bcl2, and twofold in control cells; (v) in current-clamped cells the depolarization evoked by K+ generated a more hyperpolarized voltage step in Bcl2, as compared to control cells. Taken together, our experiments suggest that the reduction of the [Ca2+]c and [Ca2+]m transients elicited by K+, in PC12 cells overexpressing Bcl2, is related to the reduction of Ca2+ entry through L-type Ca2+ channels. This may be due to the fact that Bcl2 mitigates cell depolarization, thus diminishing the recruitment of L-type Ca2+ channels, the subsequent Ca2+ entry, and mitochondrial Ca2+ overload. [Copyright &y& Elsevier]

The mechanism of blockade of P/Q Ca2+ channels by antimigraine, dotarizine, was studied in voltage-clamped bovine adrenal chromaffin cells. Inward currents through P/Q channels were pharmacologically isolated by superfusing the cells with ω-conotoxin GVIA (1 μM) plus nifedipine (3 μM). Dotarizine (10–30 μM) blocked the P/Q fraction of IBa and promoted current inactivation. Thus, dotarizine caused a greater blockade of the late IBa, compared with blockade of the early peak IBa. This effect was more prominent, the longer was the duration of the depolarising pulse. The blockade of IBa was also greater at more depolarising holding potentials (i.e. −60 mV), than was the blockade produced at more hyperpolarising holding potentials (i.e. −80 or −110 mV). Catecholamine secretory responses to brief pulses (2 s) of a Krebs-HEPES solution containing 100 mM K+ and 2 mM Ca2+ was blocked by 3 μM dotarizine. Blockade was faster and greater when dotarizine was applied on cells that were previously depolarised with Krebs-HEPES deprived of Ca2+ and containing increasing concentrations of K+. This voltage-dependent blockade of P/Q channels and exocytosis might be the underlying mechanism explaining the dotarizine prophylaxis of migraine attacks. [Copyright &y& Elsevier]

Therapeutic options for amyotrophic lateral sclerosis (ALS) are scarce and controversial. Although the aetiology of neuronal vulnerability is unknown, growing evidence supports a complex network in which multiple toxicity pathways, rather than a single mechanism, are involved in the pathogenesis of ALS. However, most cellular models only explain single pathogenic mechanisms. The present study proposes the two main cytotoxic mechanisms: (1) veratridine (VTD), which induced Na + and Ca 2+ overload; and (2) the TARD DNA-binding protein 43 (TDP-43) in NSC-34 cell line as an in vitro model of ALS. The study was carried out by MTT as an indirect measurement of cell viability and by flow cytometry to determine cell death stages. The impact of Ca 2+ overload combined with TDP-43 overexpression increased early apoptosis of NSC-34 cells. Furthermore, we found that ITH33/IQM9.21 (ITH33) exerted a neuroprotective effect in this model by reducing activation of the apoptotic pathway. Therefore, treatment with VTD in TDP-43 overexpressing NSC-34 cells is a good in vitro ALS model that makes it possible to test new neuroprotective compounds such as ITH33. [ABSTRACT FROM AUTHOR]

The mutated form of the Ca²⁺channel CALHM1 (Ca²⁺homeostasis modulator 1), P86L-CALHM1, has been correlated with early onset of Alzheimer's disease (AD). P86L-CALHM1 increases production of amyloid beta (Aβ) upon extracellular Ca²⁺removal and its subsequent addback. The aim of this study was to investigate the effect of the overexpression of CALHM1 and P86L-CALHM, upon Aβ treatment, on the following: (i) the intracellular Ca²⁺signal pathway; (ii) cell survival proteins ERK1/2 and Ca²⁺/cAMP response element binding (CREB); and (iii) cell vulnerability after treatment with Aβ. Using aequorins to measure the effect of nuclear Ca²⁺concentrations ([Ca²⁺]n ) and cytosolic Ca²⁺concentrations ([Ca²⁺]c ) on Ca²⁺entry conditions, we observed that baseline [Ca²⁺]n was higher in CALHM1 and P86L-CALHM1 cells than in control cells. Moreover, exposure to Aβ affected [Ca²⁺]c levels in HeLa cells overexpressing CALHM1 and P86L-CALHM1 compared with control cells. Treatment with Aβ elicited a significant decrease in the cell survival proteins p-ERK and p-CREB, an increase in the activity of caspases 3 and 7, and more frequent cell death by inducing early apoptosis in P86L-CALHM1-overexpressing cells than in CALHM1 or control cells. These results suggest that in the presence of Aβ, P86L-CALHM1 shifts the balance between neurodegeneration and neuronal survival toward the stimulation of pro-cytotoxic pathways, thus potentially contributing to its deleterious effects in AD., (© 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.)