Orai1 Channel Inhibition Preserves Left Ventricular Systolic Function and Normal Ca2+ Handling After Pressure Overload

Background: Orai1 is a critical ion channel subunit, best recognized as a mediator of storeoperated Ca2+ entry (SOCE) in non-excitable cells. SOCE has recently emerged as a key contributor of cardiac hypertrophy and heart failure but the relevance of Orai1 is still unclear. Methods: To test the role of these Orai1 channels in the cardiac pathophysiology, a transgenic mouse was generated with cardiomyocyte-specific expression of an ion pore-disruptive Orai1R91W mutant (C-dnO1). Synthetic chemistry and channel screening strategies were used to develop JPIII, a small-molecule Orai1 channel inhibitor suitable for in vivo delivery. Results: Adult mice subjected to transverse aortic constriction (TAC) developed cardiac hypertrophy and reduced ventricular function associated with increased Orai1 expression and Orai1-dependent SOCE (assessed by Mn2+ influx). C-dnO1 mice displayed normal cardiac electromechanical function and cellular excitation-contraction coupling despite reduced Orai1-dependent SOCE. 5 weeks after TAC, C-dnO1 mice were protected from systolic dysfunction (assessed by preserved left ventricular fractional shortening and ejection fraction) even if increased cardiac mass and pro-hypertrophic markers induction were observed. This is correlated with a protection from TAC-induced cellular Ca2+ signaling alterations (increased SOCE, decreased [Ca2+]i transients amplitude and decay rate, lower SR Ca2+ load and depressed cellular contractility) and SERCA2a downregulation in ventricular cardiomyocytes from C-dnO1 mice, associated with blunted Pyk2 signaling. There was also less fibrosis in heart sections from CdnO1 mice after TAC. Moreover, 3 weeks treatment with JPIII following 5 weeks of TAC confirmed the translational relevance of an Orai1 inhibition strategy during hypertrophic insult. Conclusions: The findings suggest a key role of cardiac Orai1 channels and the potential for Orai1 channel inhibitors as inotropic therapies for maintaining contractility reserve after hypertrophic stress

Posterior segment causes of reduced visual acuity after phacoemulsification in eyes with cataract and obscured fundus view

Hisham M Jammal,1,3 Yousef Khader,2 Riham Shawer,3 Muawyah Al Bdour41Department of Ophthalmology, Jordan University of Science and Technology, Irbid, Jordan; 2Department of Community Medicine, Public Health and Family Medicine, Jordan University of Science and Technology, Irbid, Jordan; 3Department of Ophthalmology, King Abdullah University Hospital, Irbid, Jordan; 4Department of Ophthalmology, The University of Jordan, Amman, JordanPurpose: To determine posterior segment causes of reduced visual acuity after phacoemulsification in eyes with cataract and obscured fundus view.Patients and methods: Retrospective review of medical records of patients with cataract, obscured fundus view, and normal B-scan ultrasonography, undergoing phacoemulsification from May 2005 to March 2012 was conducted. Eyes with fundus pathology, previous trauma, surgery, glaucoma, amblyopia, or uveitic cataract were excluded. Ocular comorbid conditions, preoperative visual acuity (VA), intraoperative and early postoperative complications, and final best corrected visual acuity (BCVA) at 1 month were abstracted from the records.Results: All 201 eyes of 179 patients studied had a preoperative VA of ≤6/60. Preoperative ocular comorbidity was present in 31 eyes (15.5%). Intraoperative complications occurred in 20 eyes (10%). Postoperative complications developed in 34 eyes (17.0%). One month postoperatively, 175 eyes (87.1%) achieved a BCVA of ≥6/12; whereas 26 eyes (12.9%) achieved a BCVA of ≤6/18. The most common posterior segment causes of reduced VA in the 26 eyes were age-related macular disease in ten eyes (38.5%) and diabetic maculopathy in six eyes (23.1%). Similar fundus pathology was seen preoperatively in the fellow fundus in 10 of the 26 eyes (38.5%).Conclusion: One month after phacoemulsification in eyes with cataract and obscured fundus view, age-related macular disease and diabetic maculopathy were the most common posterior segment causes of reduced final BCVA. To avoid postsurgical dissatisfaction, patients with obscured fundus view in their preoperative eye should be counseled, especially if posterior segment pathology exists in their fellow eye.Keywords: B-scan ultrasonography, fundus view, macula, outcome, phacoemulsifcatio

Divergent effects of genetic and pharmacological inhibition of Nox2 NADPH oxidase on insulin resistance related vascular damage

Insulin resistance leads to excessive endothelial cell (EC) superoxide generation and accelerated atherosclerosis. The principal source of superoxide from the insulin-resistant endothelium is the Nox2 isoform of NADPH oxidase. Here we examine the therapeutic potential of Nox2 inhibition on: superoxide generation in saphenous vein EC (SVEC) from patients with advanced atherosclerosis and type 2 diabetes; and on vascular function, vascular damage and lipid deposition in Apolipoprotein E deficient (ApoE-/-) mice with EC specific insulin resistance (ESMIRO). To examine the effect of genetic inhibition of Nox2, ESMIRO mice deficient in ApoE-/- and Nox2 (ESMIRO/ApoE-/-/Nox2-/y) were generated and compared to ESMIRO/ApoE-/-/Nox2+/y littermates. To examine the effect of pharmacological inhibition of Nox2 we administered gp91dstat or scrambled peptide to ESMIRO/ApoE-/- mice. SVEC from diabetic patients had increased expression of Nox2 protein with concomitant increase in superoxide generation which could be reduced by the Nox2 inhibitor gp91dstat. After 12 weeks western diet, ESMIRO/ApoE-/-/Nox2-/y mice had reduced EC superoxide generation and greater aortic relaxation to acetylcholine. ESMIRO/ApoE-/-/Nox2-/y mice developed more lipid deposition in the thoraco-abdominal aorta with multiple foci of elastin fragmentation at the level of the aortic sinus and greater expression of intercellular adhesion molecule-1 (ICAM-1). Gp91dstat reduced EC superoxide and lipid deposition in the thoraco-abdominal aorta of ESMIRO/ApoE-/- mice without causing elastin fragmentation or increased ICAM-1 expression. These results demonstrate that insulin resistance is characterized by increased Nox2-derived vascular superoxide. Complete deletion of Nox2 in mice with EC insulin resistance exacerbates, whereas partial pharmacological Nox2 inhibition protects against, insulin resistance-induced vascular damage