T-type Ca2ϩ channels (T-channels) are involved in the control of neuronal excitability and their gating can be modulated by a variety of redox agents. Ascorbate is an endogenous redox agent that can function as both an anti-and pro-oxidant. Here, we show that ascorbate selectively inhibits native Ca v 3.2 T-channels in peripheral and central neurons, as well as recombinant Ca v 3.2 channels heterologously expressed in human embryonic kidney 293 cells, by initiating the metal-catalyzed oxidation of a specific, metal-binding histidine residue in domain 1 of the channel. Our biophysical experiments indicate that ascorbate reduces the availability of Ca v 3.2 channels over a wide range of membrane potentials, and inhibits Ca v 3.2-dependent low-threshold-Ca 2ϩ spikes as well as burst-firing in reticular thalamic neurons at physiologically relevant concentrations. This study represents the first mechanistic demonstration of ion channel modulation by ascorbate, and suggests that ascorbate may function as an endogenous modulator of neuronal excitability.

Ectopic Mer expression promotes pro-survival signaling and contributes to leukemogenesis and chemoresistance in childhood acute lymphoblastic leukemia (ALL). Consequently, Mer kinase inhibitors may promote leukemic cell death and further act as chemosensitizers increasing efficacy and reducing toxicities of current ALL regimens. We have applied a structure-based design approach to discover novel small molecule Mer kinase inhibitors. Several pyrazolopyrimidine derivatives effectively inhibit Mer kinase activity at sub-nanomolar concentrations. Furthermore, the lead compound shows a promising selectivity profile against a panel of 72 kinases and has excellent pharmacokinetic properties. We also describe the crystal structure of the complex between the lead compound and Mer, opening new opportunities for further optimization and new template design.

Antihypertensive drugs of the "calcium channel blocker" or "calcium antagonist" class have been used to establish the physiological role of L-type Ca 2ϩ channels in vascular smooth muscle. In contrast, there has been limited progress on the pharmacology T-type Ca 2ϩ channels. T-type channels play a role in cardiac pacemaking, aldosterone secretion, and renal hemodynamics, leading to the hypothesis that mixed T-and L-type blockers may have therapeutic advantages over selective L-type blockers. The goal of this study was to identify compounds that block the Ca v 3.2 T-type channel with high affinity, focusing on two classes of compounds: phenylalkylamines (e.g., mibefradil) and dihydropyridines (e.g., efonidipine).Compounds were tested using a validated Ca 2ϩ influx assay into a cell line expressing recombinant Ca v 3.2 channels. This study identified four clinically approved antihypertensive drugs (efonidipine, felodipine, isradipine, and nitrendipine) as potent T-channel blockers (IC 50 Ͻ 3 M). In contrast, other widely prescribed dihydropyridines, such as amlodipine and nifedipine, were 10-fold less potent, making them a more appropriate choice in research studies on the role of L-type currents. In summary, the present results support the notion that many available antihypertensive drugs block a substantial fraction of T-current at therapeutically relevant concentrations, contributing to their mechanism of action.Calcium influx into cells is a key signal transduction event that leads to a myriad of responses. Calcium enters the cytosol either through plasma membrane ion channels or is released from intracellular pools. Plasma membrane ion channels can be activated by hormones, in the case of receptor-operated channels; depletion of intracellular stores, for so-called store-operated channels; or by membrane depolarization, for voltage-gated channels. Voltage-gated channels can be further classified by their pharmacology. The first class recognized were the L-type channels (Godfraind et al., 1986;Striessnig, 1999;Triggle, 2003), which were identified by their sensitivity to "calcium antagonists." Molecular biology has further expanded the repertoire of Ca 2ϩ channels, with the cloning of 10 ␣ 1 subunits of voltage-activated Ca 2ϩ

smoking but also to help keep those who quit from relapsing back to smoking.

The application of human embryonic stem cell (hESC) derivatives to regenerative medicine is now becoming a reality. Although the vast majority of hESC lines have been derived for research purposes only, about 50 lines have been established under Good Manufacturing Practice (GMP) conditions. Cell types differentiated from these designated lines may be used as a cell therapy to treat macular degeneration, Parkinson’s, Huntington’s, diabetes, osteoarthritis and other degenerative conditions. It is essential to know the genetic stability of the hESC lines before progressing to clinical trials. We evaluated the molecular karyotype of 25 clinical-grade hESC lines by whole-genome single nucleotide polymorphism (SNP) array analysis. A total of 15 unique copy number variations (CNVs) greater than 100 kb were detected, most of which were found to be naturally occurring in the human population and none were associated with culture adaptation. In addition, three copy-neutral loss of heterozygosity (CN-LOH) regions greater than 1 Mb were observed and all were relatively small and interstitial suggesting they did not arise in culture. The large number of available clinical-grade hESC lines with defined molecular karyotypes provides a substantial starting platform from which the development of pre-clinical and clinical trials in regenerative medicine can be realised.