Pharmacological Antagonism of T-Type Calcium Channels Constrains Rebound Burst Firing in Two Distinct Subpopulations of GABA Neurons in the Rat Ventral Tegmental Area: Implications for α-Lipoic Acid.

The ventral tegmental area (VTA) is a midbrain region highly involved in motivation and reward. A large body of work has investigated synaptic plasticity and ion channel excitability in this area, which has strong implication in drug abuse. We recently provided electrophysiological and pharmacological evidence that the CaV3.1 isoform of T-type voltage-gated calcium channels contributes to the excitability of VTA dopamine (DA) neurons. However, the role of T-channels in excitability of VTA gamma-amino-butyric acid (GABA) neurons remained unaddressed. Here, with a population study of rat VTA GABA neurons, we provide evidence that T-channels contribute to rebound spiking activity in two phenotypically distinct subpopulations of GABAergic neurons, each with differing electrophysiological characteristics. Additionally, we provide the first study to investigate the effect of α-lipoic acid (ALA) on ion channels in mesolimbic reward circuitry. Taken together, our population study and pharmacology experiments implicate T-channels as a target for therapies aimed at tempering VTA and mesolimbic circuit excitability.

Interface-induced magnetic polar metal phase in complex oxides.

Polar metals are commonly defined as metals with polar structural distortions. Strict symmetry restrictions make them an extremely rare breed as the structural constraints favor insulating over metallic phase. Moreover, no polar metals are known to be magnetic. Here we report on the realization of a magnetic polar metal phase in a BaTiO3/SrRuO3/BaTiO3 heterostructure. Electron microscopy reveals polar lattice distortions in three-unit-cells thick SrRuO3 between BaTiO3 layers. Electrical transport and magnetization measurements reveal that this heterostructure possesses a metallic phase with high conductivity and ferromagnetic ordering with high saturation moment. The high conductivity in the SrRuO3 layer can be attributed to the effect of electrostatic carrier accumulation induced by the BaTiO3 layers. Density-functional-theory calculations provide insights into the origin of the observed properties of the thin SrRuO3 film. The present results pave a way to design materials with desired functionalities at oxide interfaces.

Toxic anterior segment syndrome and possible association with ointment in the anterior chamber following cataract surgery.

PURPOSE: To report clinical and laboratory findings of 8 cases of toxic anterior segment syndrome (TASS) related to an oily substance in the anterior chamber of patients following cataract surgery with intraocular lens (IOL) implantation. SETTING: John Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: Eight patients had uneventful phacoemulsification by the same surgeon via clear corneal incisions with implantation of the same 3-piece silicone IOL design. Postoperative medications included antibiotic/steroid ointment and pilocarpine gel; each eye was firmly patched at the end of the procedure. On the first postoperative day, some patients presented with diffuse corneal edema, increased intraocular pressure, and an oily film-like material within the anterior chamber coating the corneal endothelium. The others presented with an oily bubble floating inside the anterior chamber, which was later seen coating the IOL. Additional surgical procedures required included penetrating keratoplasty, IOL explantation, and trabeculectomy. Two corneal buttons were analyzed histopathologically. Two explanted IOLs had gross and light microscopic analyses (as well as surface analyses of 1 of them), and 4 other explanted IOLs had gas chromatography-mass spectrometry. RESULTS: Pathological examination of the corneas showed variable thinning of the epithelium with edema. The stroma was diffusely thickened and the endothelial cell layer was absent. Evaluation of the explanted IOLs confirmed the presence of an oily substance coating large areas of their anterior and posterior optic surfaces. Gas chromatography-mass spectrometry of the lens extracts identified a mixed chain hydrocarbon compound that was also found in the gas chromatography-mass spectrometry analyses of the ointment used postoperatively. CONCLUSIONS: The results indicate that the ointment gained access to the eye, causing the postoperative complications described. These cases highlight the importance of appropriate wound construction and integrity, as well as the risks of tight eye patching following placement of ointment.