Endothelial dysfunction develops with age and may precede cardiovascular disease. Animal data suggest that T-type calcium channels play an important role in endothelial function, but data from humans are lacking. This study included 15 healthy, sedentary, elderly males for a double blinded, randomized controlled trial. For 8 weeks, they were given 40 mg/day of either efonidipine (L- and T-type calcium channel blocker (CCB)) or nifedipine (L-type CCB). Vascular function was evaluated by graded femoral arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator) both with and without co-infusion of N-acetylcysteine (NAC; antioxidant). We measured leg blood flow and mean arterial pressure and calculated leg vascular conductance to evaluate the leg vascular responses. Despite no significant change in blood pressure in either group, we observed higher leg blood flow responses (Δ 0.43 ± 0.45 l/min, P = 0.006) and leg vascular conductance (Δ 5.38 ± 5.67 ml/min/mmHg, P = 0.005) to intra-arterial ACh after efonidipine, whereas there was no change in the nifedipine group, and no differences between groups. We found no upregulation of endothelial nitric oxide synthase in vastus lateralis muscle biopsies within or between groups. Smooth muscle cell responsiveness was unaltered by efonidipine or nifedipine. Intravenous co-infusion of NAC did not affect endothelium-dependent vasodilatation in either of the CCB groups. These results suggest that 8 weeks\' inhibition of T- and L-type calcium channels augments endothelium-dependent vasodilatory function in healthy elderly males. Further studies are required to elucidate if T-type calcium channel inhibition can counteract endothelial dysfunction.

OBJECTIVE: CACNA1H is regarded as a gene conferring susceptibility to generalised epilepsy. However, the prognosis of epilepsy patients carrying the CACNA1H missense variants of uncertain significance (VUS) is unknown. A prospective cohort was generated to determine the deleterious effects of these variants and to check whether the presence of these variants affects the prognosis of epilepsy patients.
METHODS: This study was conducted at Xijing Hospital in Xian, China. All patients were followed up for at least 1 year. Previous reports were searched for previously reported variants. Ensembl database was searched for variants in the general population. Combined Annotation Dependent Depletion (CADD) was used to evaluate the deleterious effect of variants. Logistic regression and Cox regression were used for data analysis.
RESULTS: The study included 176 epilepsy patients with or without CACNA1H variants. In epilepsy patients with missense variants, we found 35 different variants, including 33 variants with uncertain significance and 2 likely benign variants. No significant difference was observed between the distribution of CADD scores of the variants from this cohort, of the general population, and of those found in previous reports. Among epilepsy patients with missense variants, the number of antiepileptic drugs (AEDs) administered to the patients, a first-degree family history of epilepsy, and possibly the presence of abnormalities in brain radiology findings were correlated with the poorer prognosis. Among the entire cohort, the type of epilepsy, number of AEDs administered, and presence of abnormalities in brain radiology findings were associated with the prognosis of these patients. The deleterious effect of CACNA1H missense variants or their presence was not related to the prognosis of epilepsy patients.
CONCLUSIONS: The results of our study suggest that CACNA1H variants are related to multiple epilepsy syndromes. However, there is no strong evidence of the correlation between CACNA1H missense variants and a certain type of epilepsy. In our study cohort, both the deleterious effects and the presence of CACNA1H variants were found to be unrelated to the prognosis of patients with epilepsy. These findings suggest that CACNA1H missense variants that are classified as VUS might not influence the outcome of epilepsy.

Early-onset severe spinocerebellar ataxia 42 with neurodevelopmental deficits (SCA42ND, MIM#604065) is an ultrarare autosomal dominant syndrome related to de novo CACNA1G gain-of-function pathogenic variants. All patients with SCA42ND show cerebellar atrophy and/or hypoplasia on neuroimaging and share common features such as dysmorphic features, global developmental delay, and axial hypotonia, all manifesting within the first year of life. To date, only 10 patients with SCA42ND have been reported with functionally confirmed gain-of-function variants, bearing either of two recurrent pathogenic variants. We describe a girl with congenital ataxia, without epilepsy, and a de novo p.Ala961Thr pathogenic variant in CACNA1G. We review the published subjects with the aim of better characterizing the dysmorphic features that may be crucial for clinical recognition of SCA42ND. Cerebellar atrophy, together with digital anomalies, particularly broad thumbs and/or halluces, should lead to clinical suspicion of this disease. We describe the first pharmacological attempt to treat a patient with SCA42ND using zonisamide, an antiepileptic drug with T-type channel blocker activity, in an off-label indication using an itemized study protocol. No efficacy was observed at the dose tested. However, without pharmacological treatment, she showed a positive evolution in neurodevelopment during the follow-up.

ACT-709478 is a selective, orally available T-type calcium channel blocker being studied as a potential new treatment in epilepsy. ACT-709478 had previously been investigated in a single-ascending dose study up to a dose of 400 mg.
The aim of this study was to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple doses of ACT-709478. In addition, the drug-drug interaction potential of multiple doses of ACT-709478 with the cytochrome P450 3A4 substrate midazolam was investigated.
This double-blind, placebo-controlled, randomized study included 46 healthy male and female subjects. Ascending multiple oral doses of ACT-709478 were administered to 10 (cohorts 1-2) or 12 (cohorts 3-4) subjects (two taking placebo per cohort). In cohorts 1-2, 30 or 10 mg ACT-709478 was administered once daily for 12 days. An up-titration regimen was used in cohorts 3-4 with administration of 10, 30, and 60 mg for 7 days each in both cohorts and an additional dose level of 100 mg ACT-709478 once daily for 8 days in cohort 4. Single doses of midazolam were administered at baseline and concomitantly to 60 mg and 100 mg ACT-709478 in cohort 4. Blood sampling for pharmacokinetic evaluations and safety assessments (clinical laboratory, vital signs, adverse events, and electrocardiogram) were performed regularly. Holter electrocardiograms were recorded at baseline and for 24 h at steady state and central nervous system effects were assessed with pharmacodynamic tests at baseline and steady state.
ACT-709478 was absorbed with a time to reach the maximum plasma concentration of 3.5-4.0 h and eliminated with a half-life of 45-53 h. Steady state was reached after 5-7 days of dosing and exposure increased dose-proportionally. An accumulation index of approximately three fold was observed in cohorts 1 and 2. Exposure to midazolam was lower upon concomitant administration of 60 and 100 mg ACT-709478 compared to midazolam alone while the half-life and time to reach the maximum plasma concentration of midazolam remained unchanged, suggesting a weak induction at the gastrointestinal but not hepatic level. Pharmacokinetic parameters of 1-hydroxymidazolam were not affected by ACT-709478 administration. The most frequent adverse events were dizziness, somnolence, and headache. A tolerability signal was detected in cohort 1 (30 mg once daily); therefore, the dose was decreased to 10 mg once daily in cohort 2. The subsequently established up-titration regimen, starting with 10 mg once daily, considerably improved tolerability. Multiple doses up to 100 mg once daily were well tolerated. No treatment-related effects were detected on vital signs, clinical laboratory tests, Holter electrocardiogram variables, or in the pharmacodynamic tests.
ACT-709478 exhibits good tolerability up to 100 mg once daily using an up-titration regimen and pharmacokinetic properties that support further clinical investigations. A weak induction of gastrointestinal cytochrome P450 3A4 activity was observed, unlikely to be of clinical relevance. CLINICALTRIALS.
NCT03165097.

Genetic generalized epilepsies (GGE) (childhood absence epilepsy (CAE), juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures (GTCS)) are mainly determined by genetic factors. Since few mutations were identified in rare families with autosomal dominant GGE, a polygenic inheritance was suspected in most patients. Recent studies on large American or European cohorts of sporadic cases showed that susceptibility genes were numerous although their variants were rare, making their identification difficult. Here, we reported clinical and genetic characteristics of 30 Tunisian GGE families, including 71 GGE patients. The phenotype was close to that in sporadic cases. Nineteen pedigrees had a homogeneous type of GGE (JME-CAE-CGTS), and 11 combined these epileptic syndromes. Rare non-synonymous variants were selected in probands using a targeted panel of 30 candidate genes and their segregation was determined in families. Molecular studies incriminated different genes, mainly CACNA1H and MAST4. The segregation of at least two variants in different genes in some pedigrees was compatible with the hypothesis of an oligogenic inheritance, which was in accordance with the relatively low frequency of consanguineous probands. Since at least 2 susceptibility genes were likely shared by different populations, genetic factors involved in the majority of Tunisian GGE families remain to be discovered. Their identification should be easier in families with a homogeneous type of GGE, in which an intra-familial genetic homogeneity could be suspected.

Masking effects of a preceding stimulus on the detection or perception of a signal have been found in several sensory systems in mammals, including humans and rodents. In the auditory system, it has been hypothesized that a central \"OFF-inhibitory\" mechanism, which is generated by neurons that respond after a sound is terminated, may contribute to the observed psychophysics. The present study constructed a systems model for the inferior colliculus that includes major ascending monaural and binaural auditory pathways. The fundamental characteristics of several neuron types along the pathways were captured by Hodgkin-Huxley models with specific membrane and synaptic properties. OFF responses were reproduced with a model of the superior paraolivary nucleus containing a hyperpolarization-activated h current and a T-type calcium current. When the gap between the end of the masker and the onset of the signal was large, e.g., >5 ms, OFF inhibition generated strong suppressive effects on the signal response. For smaller gaps, an additional inhibitory source, which was modeled as ON inhibition from the contralateral dorsal nucleus of the lateral lemniscus, showed the potential of explaining the psychophysics. Meanwhile, the effect of a forward masker on the binaural sensitivity to a low-frequency signal was examined, which was consistent with previous psychophysical findings related to sound localization.

This randomized, double-blind, placebo-controlled, crossover trial evaluated the pharmacodynamic effects of a single 100-mg dose of ABT-639, a peripherally active, selective T-type Cav3.2 channel blocker, with the intradermal capsaicin pain model using pregabalin 300 mg as a positive control.
Healthy adult males (aged 21 to 55 years) were randomly assigned to receive single oral doses of ABT-639, pregabalin, and placebo.
Serial measurements for area (cm2) of hyperalgesia, allodynia, and flare response were performed over a 20-minute period after each capsaicin injection at 1 and 4 hours post-dose. Capsaicin injections were administered in different arms as determined by random assignment. Serial measurements for spontaneous pain and elicited pain were performed over a 60-minute period at 1 and 4 hours post-dose using a 100-mm visual analog scale. Standard safety evaluations were performed.
Nineteen participants were randomized and included in the analysis. No significant differences were observed between ABT-639 and placebo in spontaneous pain, elicited pain, and areas of allodynia, hyperalgesia, and flare after intradermal capsaicin injection at 1 and 4 hours post-dose. In contrast, pregabalin demonstrated significant reductions in spontaneous pain at 1 and 4 hours post-dose, and elicited pain and areas of allodynia and hyperalgesia at 4 hours post-dose compared with placebo. ABT-639 demonstrated acceptable safety and tolerability; somnolence and euphoric mood were the most commonly reported adverse events.
These data indicate that a single 100-mg dose of ABT-639 had no effect on experimental pain induced by intradermal capsaicin injection.

The expanding \"valley of death\" in drug development is leaving potentially life-saving new chemical entities and molecular targets fallow. This situation is forcing early-stage companies to think creatively about moving their technologies forward, especially as institutional investors show more interest in later stages of development. Drug repurposing, a strategy to examine existing drugs for therapeutic value against different diseases, is an emerging method to bring an off-market drug back onto the market. Tau Therapeutics LLC identified the role of T-type calcium channel blockers (Cav3) in cancer proliferation, but the company was unable to attract funding while having both a nonvalidated drug target and new chemical entities. To change the risk profile of the company, Tau set out to repurpose the known Cav3 drug mibefradil as a proof of concept for the treatment of cancer. Mibefradil was launched for hypertension in the 1990s but withdrawn because of drug-drug interactions. A new sequential combination treatment, termed Interlaced Therapy™, uses short-term administration of mibefradil to enhance the overall therapeutic potential of conventional anticancer agents. Mibefradil is currently in a phase Ib clinical trial with the National Cancer Institute (NCI) Adult Brain Tumor Consortium. Mibefradil has been repurposed from an abandoned antihypertensive to a targeted solid tumor treatment, and it has been rescued from drug-drug interactions by using short-term dose exposure. Tau is using the early success of mibefradil as a proof of concept to build a platform technology of Cav3 blockers for broad antitumor applications in combination with new targeted cancer therapies, well-established chemotherapies, and radiation.

1,4-Dihydropyridines (DHPs) have been developed to treat hypertension, angina, and nerve system disease. They are thought to mainly target the L-type calcium channels, but low selectivity prompts them to block Cav1.2 and Cav3.1 channels simultaneously. Recently, some novel DHPs with different hydrophobic groups have been synthesized and among them M12 has a higher selectivity for Cav3.1. However, the structural information about Cav3.1-DHPs complexes is not available in the experiment. Thus, we combined homology modeling, molecular docking, molecular dynamics simulations, and binding free energy calculations to quantitatively elucidate the inhibition mechanism of DHPs. The calculated results indicate that our model is in excellent agreement with experimental results. On the basis of conformational analysis, we identify the main interactions between DHPs and calcium channels and further elaborate on the different selectivity of ligands from the micro perspective. In conjunction with energy distribution, we propose that the binding sites of Cav3.1-DHPs is characterized by several interspersed hydrophobic amino acid residues on the IIIS6 and IVS6 segments. We also speculate the favorable function groups on prospective DHPs. Besides, our model provides important information for further mutagenesis experiments.

OBJECTIVE: As important ion channels of the central nervous system, calcium channels not only take part in epileptogenesis but also act as the targets of commonly used antiepileptic drugs (AEDs). Thus, this study aimed to provide the first investigation of the association between CACNA1A, CACNA1C, and CACNA1H single nucleotide polymorphisms (SNPs) and AED resistance in the Chinese Han population.
METHODS: We performed genotyping of tagging single nucleotide polymorphisms (tagSNPs) of CACNA1A, 1C and 1H in 480 Chinese epilepsy patients (288 drug-responsive and 192 drug-resistant patients). The Illumina GoldenGate BeadArray assay was used to detect the genotypes of all of the patients. A total of 15 SNPs were selected based on the HapMap database. The genotype distributions in drug-responsive and drug-resistant patients were compared, and the haplotype frequencies of each gene were calculated.
RESULTS: None of the 15 tagSNPs alleles were found to be associated with drug-resistant epilepsy. However, the frequency of the TAGAA haplotype in CACNA1A was significantly higher in drug-resistant patients than in drug-responsive patients after the correction of multiple comparisons with Bonferroni\'s method (TAGAA 13.3% vs. 7.1%, OR=2.129 [1.373-3.299], P=0.00059<0.05/10).
CONCLUSIONS: This study revealed no association between the 15 tagSNPs of CACNA1A, 1C, and 1H and drug efficacy in the Chinese Han population. The TAGAA haplotype of CACNA1A may be a risk factor for AED resistance.