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Chovanec E. Utilizing Involuntary Unfolding Phenomena as Catalyst for Adaptive Responsiveness and Reorganization. Int J Clin Exp Hypn 2024:1-21. [PMID: 39167032 DOI: 10.1080/00207144.2024.2381440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/08/2024] [Accepted: 07/10/2024] [Indexed: 08/23/2024]
Abstract
This paper explores the complex area of so-called unfolding processes and unfolding phenomena in hypnotherapy, emphasizing on unfolding movements and unfolding images, identified as complex involuntary phenomena, which emerge spontaneously without suggestions for these phenomena. Unfolding phenomena are examined as foundational elements of the unfolding process. On the one hand, the study unveils the macro-structure of the unfolding process by categorizing it into involuntary unfolding sets, phases, and unfolding subunits, all of which are analogous among patients and across different organizational levels. On the other hand, detailing the micro-structure aids in elucidating the functionality and elements of the unfolding phenomena. These elements encompass unfolding schemas and instruments. They are emphasized for their role in intrapsychic ideodynamics and responsiveness, aiding recurrent induction aligned and being promoted via an intuitive state of consciousness. Unfolding phenomena elucidate resource elicitation, and adaptation, contributing to the phenotypic organization and reorganization. In this context, the mechanisms of responsiveness, characterized by an unfolding process during hypnotherapy with distinct phases, are examined to help therapists and researchers understand how hypnotherapy can induce phenotypic changes, thereby facilitating treatment, personal growth, and the emergence of a new form of consciousness.
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Affiliation(s)
- Erika Chovanec
- Psychotherapy, Growth- & Unfolding-Motivation Center Vienna, Vienna, Austria
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2
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Umeya N, Yoshizawa Y, Fukuda K, Ikeda K, Kamada M, Inada H, Usui T, Miyawaki I. Detection of retinal dysfunction induced by HCN channel inhibitors using multistep light stimulus and long-duration light stimulus ERG in rats. Exp Eye Res 2024; 241:109847. [PMID: 38401854 DOI: 10.1016/j.exer.2024.109847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/01/2024] [Accepted: 02/21/2024] [Indexed: 02/26/2024]
Abstract
Ivabradine, a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel inhibitor, has been reported to induce photosensitivity-related visual disturbances such as phosphene in humans. Ivabradine-induced visual disturbances are caused by inhibition of HCN channels in the retina, and the mechanisms have been verified using HCN channel knockout mice and electroretinography (ERG). However, in rats, classical ERG using single flash light stimulus with standard analyses of waveform amplitude and latency has not revealed abnormal retinal function after administration of ivabradine. To verify whether retinal dysfunction after ivabradine administration was detectable in rats, we performed ERG using multistep flash light stimulation at the time when plasma concentration of ivabradine was high. Furthermore, the mechanism of the change in the waveform that appeared after the b-wave was investigated. Ivabradine and cilobradine, a selective HCN channel inhibitor, were administered subcutaneously to rats at 4-40 mg/kg as a single dose, and flash or long-duration ERG recordings at each light stimulus luminance were conducted 1.5 h after administration. Plasma and retinal concentrations of both compounds were measured immediately after the ERG recordings. In the flash ERG, prolongation of a- and/or b-wave latencies were detected at each light stimulus, and dose-dependent waveform changes after the b-wave were recorded at the specific light stimulus luminance for both compounds. These ERG changes increased in response to increasing plasma and retinal concentrations for both ivabradine and cilobradine. In the long-duration light stimulus ERG, a change in the waveform of the b-wave trough and attenuation of the c-wave were recorded, suggesting that the feedback control in the photoreceptor cells may be inhibited. This study revealed that the retinal dysfunction by HCN channel inhibitors in rats can be detected by multistep light stimulus ERG. Additionally, we identified that the inhibition of feedback current and the sustained responses in the photoreceptor cells cause the retinal dysfunction of HCN channel inhibitors in rats.
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Affiliation(s)
- Naohisa Umeya
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan.
| | - Yuki Yoshizawa
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Kosuke Fukuda
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Keigo Ikeda
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Mami Kamada
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Hiroshi Inada
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Toru Usui
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
| | - Izuru Miyawaki
- Preclinical Research Unit, Drug Research Division, Sumitomo Pharma Co. Ltd., 3-1-98 Kasugade-naka, Konohana-ku, Osaka, 554-0022, Japan
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Kim D, Roh H, Lee HM, Kim SJ, Im M. Localization of hyperpolarization-activated cyclic nucleotide-gated channels in the vertebrate retinas across species and their physiological roles. Front Neuroanat 2024; 18:1385932. [PMID: 38562955 PMCID: PMC10982330 DOI: 10.3389/fnana.2024.1385932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 03/06/2024] [Indexed: 04/04/2024] Open
Abstract
Transmembrane proteins known as hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control the movement of Na+ and K+ ions across cellular membranes. HCN channels are known to be involved in crucial physiological functions in regulating neuronal excitability and rhythmicity, and pacemaker activity in the heart. Although HCN channels have been relatively well investigated in the brain, their distribution and function in the retina have received less attention, remaining their physiological roles to be comprehensively understood. Also, because recent studies reported HCN channels have been somewhat linked with the dysfunction of photoreceptors which are affected by retinal diseases, investigating HCN channels in the retina may offer valuable insights into disease mechanisms and potentially contribute to identifying novel therapeutic targets for retinal degenerative disorders. This paper endeavors to summarize the existing literature on the distribution and function of HCN channels reported in the vertebrate retinas of various species and discuss the potential implications for the treatment of retinal diseases. Then, we recapitulate current knowledge regarding the function and regulation of HCN channels, as well as their relevance to various neurological disorders.
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Affiliation(s)
- Daniel Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Department of Biomedical Sciences, College of Medicine, Seoul National University (SNU), Seoul, Republic of Korea
| | - Hyeonhee Roh
- School of Electrical Engineering, College of Engineering, Korea University, Seoul, Republic of Korea
| | - Hyung-Min Lee
- School of Electrical Engineering, College of Engineering, Korea University, Seoul, Republic of Korea
| | - Sang Jeong Kim
- Department of Biomedical Sciences, College of Medicine, Seoul National University (SNU), Seoul, Republic of Korea
| | - Maesoon Im
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science & Technology (UST), Seoul, Republic of Korea
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul, Republic of Korea
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4
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Seo H, Chung WG, Kwon YW, Kim S, Hong YM, Park W, Kim E, Lee J, Lee S, Kim M, Lim K, Jeong I, Song H, Park JU. Smart Contact Lenses as Wearable Ophthalmic Devices for Disease Monitoring and Health Management. Chem Rev 2023; 123:11488-11558. [PMID: 37748126 PMCID: PMC10571045 DOI: 10.1021/acs.chemrev.3c00290] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 09/27/2023]
Abstract
The eye contains a complex network of physiological information and biomarkers for monitoring disease and managing health, and ocular devices can be used to effectively perform point-of-care diagnosis and disease management. This comprehensive review describes the target biomarkers and various diseases, including ophthalmic diseases, metabolic diseases, and neurological diseases, based on the physiological and anatomical background of the eye. This review also includes the recent technologies utilized in eye-wearable medical devices and the latest trends in wearable ophthalmic devices, specifically smart contact lenses for the purpose of disease management. After introducing other ocular devices such as the retinal prosthesis, we further discuss the current challenges and potential possibilities of smart contact lenses.
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Affiliation(s)
- Hunkyu Seo
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Won Gi Chung
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yong Won Kwon
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sumin Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yeon-Mi Hong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Wonjung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Enji Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jakyoung Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sanghoon Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Moohyun Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Kyeonghee Lim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Inhea Jeong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Hayoung Song
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jang-Ung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
- Department
of Neurosurgery, Yonsei University College
of Medicine, Seoul 03722, Republic of Korea
- Center
for Nanomedicine, Institute for Basic Science (IBS), Yonsei University, Seoul 03722, Republic
of Korea
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5
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Mckenzie CE, Ho CJ, Forster IC, Soh MS, Phillips AM, Chang YC, Scheffer IE, Reid CA, Tsai MH. Impaired Color Recognition in HCN1 Epilepsy: A Single Case Report. Front Neurol 2022; 13:834252. [PMID: 35359652 PMCID: PMC8960314 DOI: 10.3389/fneur.2022.834252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
Variants in HCN1 are associated with a range of epilepsy syndromes including developmental and epileptic encephalopathies. Here we describe a child harboring a novel de novo HCN1 variant, E246A, in a child with epilepsy and mild developmental delay. By parental report, the child had difficulty in discriminating between colors implicating a visual deficit. This interesting observation may relate to the high expression of HCN1 channels in rod and cone photoreceptors where they play an integral role in shaping the light response. Functional analysis of the HCN1 E246A variant revealed a right shift in the voltage dependence of activation and slowing of the rates of activation and deactivation. The changes in the biophysical properties are consistent with a gain-of-function supporting the role of HCN1 E246A in disease causation. This case suggests that visual function, including color discrimination, should be carefully monitored in patients with diseases due to HCN1 pathogenic variants.
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Affiliation(s)
- Chaseley E. Mckenzie
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | - Chen-Jui Ho
- Division of Epilepsy, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Ian C. Forster
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | - Ming S. Soh
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | - A. Marie Phillips
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
- School of Biosciences, The University of Melbourne, Parkville, VIC, Australia
| | - Ying-Chao Chang
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Ingrid E. Scheffer
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, VIC, Australia
- Department of Paediatrics, Murdoch Children's Research Institute, Royal Children's Hospital, University of Melbourne, Parkville, VIC, Australia
| | - Christopher A. Reid
- Early Development Division, Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, VIC, Australia
| | - Meng-Han Tsai
- Division of Epilepsy, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
- School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Genomics and Proteomics Core Laboratory, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
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6
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The HCN channel as a pharmacological target: Why, where, and how to block it. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:173-181. [PMID: 34303730 DOI: 10.1016/j.pbiomolbio.2021.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 06/22/2021] [Accepted: 07/20/2021] [Indexed: 12/19/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, expressed in a variety of cell types and in all tissues, control excitation and rhythm. Since their discovery in neurons and cardiac pacemaker cells, they attracted the attention of medicinal chemistry and pharmacology as novel targets to shape (patho)physiological mechanisms. To date, ivabradine represents the first-in-class drug as specific bradycardic agent in cardiac diseases; however, new applications are emerging in parallel with the demonstration of the involvement of different HCN isoforms in central and peripheral nervous system. Hence, the possibility to target specific isoforms represents an attractive development in this field; indeed, HCN1, HCN2 or HCN4 specific blockers have shown promising features in vitro and in vivo, with remarkable pharmacological differences likely depending on the diverse functional role and tissue distribution. Here, we show a recently developed compound with high potency as HCN2-HCN4 blocker; because of its unique profile, this compound may deserve further investigation.
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Barravecchia I, Demontis GC. HCN1 channels: A versatile tool for signal processing by primary sensory neurons. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:133-146. [PMID: 34197835 DOI: 10.1016/j.pbiomolbio.2021.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/11/2021] [Accepted: 06/25/2021] [Indexed: 12/20/2022]
Abstract
Most primary sensory neurons (PSNs) generate a slowly-activating inward current in response to membrane hyperpolarization (Ih) and express HCN1 along with additional isoforms coding for hyperpolarization-activated channels (HCN). Changes in HCN expression may affect the excitability and firing patterns of PSNs, but retinal and inner ear PSNs do not fire action potentials, suggesting HCN channel roles may extend beyond excitability and cell firing control. In patients taking Ih blockers, photopsia triggered in response to abrupt changes in luminance correlates with impaired visual signal processing via parallel rod and cone pathways. Furthermore, in a mouse model of inherited retinal degeneration, HCN blockers or Hcn1 genetic ablation may worsen photoreceptors' demise. PSN's use of HCN channels to adjust either their firing rate or process signals generated by sensory transduction in non-spiking PSNs indicates HCN1 channels as a versatile tool with a novel role in sensory processing beyond firing control.
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Affiliation(s)
- Ivana Barravecchia
- Department of Pharmacy, Università di Pisa, Italy, Via Bonanno, 6, 56126, Pisa, Italy; Istitute of Life Science, Scuola Superiore Sant' Anna, 56127, Pisa, Italy.
| | - Gian Carlo Demontis
- Department of Pharmacy, Università di Pisa, Italy, Via Bonanno, 6, 56126, Pisa, Italy.
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8
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Abstract
Ivabradine is a unique agent that is distinct from beta-blockers and calcium channel blockers as it reduces heart rate without affecting myocardial contractility or vascular tone. Ivabradine is a use-dependent inhibitor targeting the sinoatrial node. It is approved for use in the United States as an adjunct therapy for heart rate reduction in patients with heart failure with reduced ejection fraction. In this scenario, ivabradine has demonstrated improved clinical outcomes due to reduction in heart failure readmissions. However, there has been conflicting evidence from prospective studies and randomized controlled trials for its use in stable ischemic heart disease regarding efficacy in symptom reduction and mortality benefit. Ivabradine may also play a role in the treatment of patients with inappropriate sinus tachycardia, who often cannot tolerate beta-blockers and/or calcium channel blockers. In this review, we highlight the evidence for the nuances of using ivabradine in heart failure, stable ischemic heart disease, and inappropriate sinus tachycardia to raise awareness for its vital role in the treatment of select populations.
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Abstract
Illusions and hallucinations are commonly encountered in both daily life and clinical practice. In this chapter, we review definitions and possible underlying mechanisms of these phenomena and then review what is known about specific conditions that are associated with them, including ophthalmic causes, migraine, epilepsy, Parkinson's disease, and schizophrenia. We then discuss specific syndromes including the Charles Bonnet syndrome, visual snow syndrome, Alice in Wonderland syndrome, and peduncular hallucinosis. The scientific study of illusions and hallucinations has contributed significantly to our understanding of how eye and brain process vision and contribute to perception. Important concepts are the distinction between topologic and hodologic mechanisms underlying hallucinations and the involvement of attentional networks. This chapter examines the various ways in which pathological illusions and hallucinations might arise in relation to the phenomenology and known pathology of the various conditions associated with them.
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Affiliation(s)
- Clare L Fraser
- Department of Ophthalmology, Save Sight Institute, Faculty of Health and Medicine, University of Sydney, Sydney, Australia.
| | - Christian J Lueck
- Department of Neurology, Canberra Hospital, and Australian National University Medical School, Canberra, Australia
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10
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Hemodynamic effects of ivabradine use in combination with intravenous inotropic therapy in advanced heart failure. Heart Fail Rev 2020; 26:355-361. [PMID: 32997214 DOI: 10.1007/s10741-020-10029-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/15/2020] [Indexed: 12/28/2022]
Abstract
Intravenous inotropic therapy can be used in patients with advanced heart failure, as palliative therapy or as a bridge to cardiac transplantation or mechanical circulatory support, as well as in cardiogenic shock. Their use is limited to increasing cardiac output in low cardiac output states and reducing ventricular filling pressures to alleviate patient symptoms and improve functional class. Many advanced heart failure patients have sinus tachycardia as a compensatory mechanism to maintain cardiac output. However, excessive sinus tachycardia caused by intravenous inotropes can increase myocardial oxygen consumption, decrease coronary perfusion, and at extreme heart rates decrease ventricular filling and stroke volume. The limited available hemodynamic studies support the hypothesis that adding ivabradine, a rate control agent without negative inotropic effect, may blunt inotrope-induced tachycardia and its associated deleterious effects, while optimizing cardiac output by increasing stroke volume. This review analyzes the intriguing pathophysiology of combined intravenous inotropes and ivabradine to optimize the hemodynamic profile of patients in advanced heart failure. Graphical abstract Illustration of the beneficial and deleterious hemodynamic effects of intravenous inotropes in advanced heart failure, and the positive effects of adding ivabradine.
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Abstract
BACKGROUND Ivabradine is a unique medication that reduces the intrinsic heart rate by specifically blocking the inward funny current that controls the pacemaker activity of the sinus node. We conducted a retrospective cohort study to assess the efficacy of ivabradine in children suffering from postural orthostatic tachycardia syndrome. METHODS A chart review was conducted of patients less than 18 years of age who were diagnosed with postural orthostatic tachycardia syndrome who had received ivabradine as treatment from January 2015 to February 2019 at our institution. Twenty-seven patients (25 females, 92.5%) were identified for the study. The outcomes which were assessed included a change in the severity and frequency of symptoms, heart rate, and blood pressure before and after starting ivabradine. RESULTS There was an improvement in the symptoms of 18 (67%) out of 27 patients. The most notable symptom affected was syncope/presyncope with a reduction in 90%, followed by lightheadedness (85%) and fatigue (81%). The vital signs of the patients showed an overall significant lowering of the heart rate during sitting (89.7 ± 17.9 versus 73.2 ± 12.1; p-value <0.05) and standing (100.5 ± 18.1 versus 80.9 ± 10.1; p-value <0.05) without a significant change in the blood pressure. Two patients had visual disturbances (luminous phenomena). Severe bradycardia and excessive flushing were seen in two patients, respectively. Another one patient reported joint pain and fatigue. CONCLUSION This study indicates that 67% of children treated with ivabradine report an improvement in symptoms.
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Abstract
'Photopsia' describes the symptom of visual disturbances that are typically flash-like, sudden in onset and brief, and occurring without light entering the eye. Patients reporting photopsia often pose a diagnostic challenge, given the wide range of possible neurological and ophthalmological causes. We review the common causes of photopsia, discuss the assessment and workup of this symptom, and stress the importance of close interdisciplinary liaison to help with its diagnosis and management. We discuss a patient with acute zonal occult outer retinopathy to illustrate these points.
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Affiliation(s)
- Jasvir Virdee
- Ophthalmology, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - Susan P Mollan
- Birmingham Neuro-Ophthalmology Unit, Ophthalmology Department, University Hospitals Birmingham NHS Trust, Birmingham, UK.,Metabolic Neurology, University of Birmingham, Birmingham, UK
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13
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Popova E, Kupenova P. Effects of HCN channel blockade on the intensity-response function of electroretinographic ON and OFF responses in dark adapted frogs. Acta Neurobiol Exp (Wars) 2020. [DOI: 10.21307/ane-2020-018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Tsutsui H, Momomura SI, Yamashina A, Shimokawa H, Kihara Y, Saito Y, Hagiwara N, Ito H, Yano M, Yamamoto K, Ako J, Inomata T, Sakata Y, Tanaka T, Kawasaki Y. Efficacy and Safety of Ivabradine in Japanese Patients With Chronic Heart Failure ― J-SHIFT Study ―. Circ J 2019; 83:2049-2060. [DOI: 10.1253/circj.cj-19-0227] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University
| | - Shin-ichi Momomura
- Cardiovascular Division, Jichi Medical University, Saitama Medical Center
| | | | - Hiroaki Shimokawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
| | - Yasuki Kihara
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical & Health Sciences
| | - Yoshihiko Saito
- First Department of Internal Medicine, Nara Medical University
| | | | - Hiroshi Ito
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Masafumi Yano
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine
| | - Kazuhiro Yamamoto
- Division of Cardiovascular Medicine, Endocrinology and Metabolism, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University
| | - Junya Ako
- Cardiovascular Medicine, Kitasato University
| | - Takayuki Inomata
- Cardiovascular Medicine, Kitasato University Kitasato Institute Hospital
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Graduate School of Medicine, Osaka University
| | - Takashi Tanaka
- Department of Clinical Development, Ono Pharmaceutical Co., Ltd
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15
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Császár N, Kapócs G, Bókkon I. A possible key role of vision in the development of schizophrenia. Rev Neurosci 2019; 30:359-379. [PMID: 30244235 DOI: 10.1515/revneuro-2018-0022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 08/01/2018] [Indexed: 12/12/2022]
Abstract
Based on a brief overview of the various aspects of schizophrenia reported by numerous studies, here we hypothesize that schizophrenia may originate (and in part be performed) from visual areas. In other words, it seems that a normal visual system or at least an evanescent visual perception may be an essential prerequisite for the development of schizophrenia as well as of various types of hallucinations. Our study focuses on auditory and visual hallucinations, as they are the most prominent features of schizophrenic hallucinations (and also the most studied types of hallucinations). Here, we evaluate the possible key role of the visual system in the development of schizophrenia.
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Affiliation(s)
- Noemi Császár
- Gaspar Karoly University Psychological Institute, H-1091 Budapest, Hungary.,Psychoszomatic Outpatient Department, H-1037 Budapest, Hungary
| | - Gabor Kapócs
- Buda Family Centred Mental Health Centre, Department of Psychiatry and Psychiatric Rehabilitation, St. John Hospital, Budapest, Hungary
| | - István Bókkon
- Psychoszomatic Outpatient Department, H-1037 Budapest, Hungary.,Vision Research Institute, Neuroscience and Consciousness Research Department, 25 Rita Street, Lowell, MA 01854, USA
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16
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Ide T, Ohtani K, Higo T, Tanaka M, Kawasaki Y, Tsutsui H. Ivabradine for the Treatment of Cardiovascular Diseases. Circ J 2018; 83:252-260. [PMID: 30606942 DOI: 10.1253/circj.cj-18-1184] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Higher heart rate (HR) is independently related to worse outcomes in various cardiac diseases, including hypertension, coronary artery disease, and heart failure (HF). HR is determined by the pacemaker activity of cells within the sinoatrial node. The hyperpolarization-activated cyclic nucleotide-gated (HCN) 4 channel, one of 4 HCN isoforms, generates the If current and plays an important role in the regulation of pacemaker activity in the sinoatrial node. Ivabradine is a novel and only available HCN inhibitor, which can reduce HR and has been approved for stable angina and chronic HF in many countries other than Japan. In this review, we summarize the current knowledge of the HCN4 channel and ivabradine, including the function of HCN4 in cardiac pacemaking, the mechanism of action of If inhibition by ivabradine, and the pharmacological and clinical effects of ivabradine in cardiac diseases as HF, coronary artery disease, and atrial fibrillation.
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Affiliation(s)
- Tomomi Ide
- Department of Experimental and Clinical Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University
| | - Kisho Ohtani
- Department of Experimental and Clinical Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University
| | - Taiki Higo
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University
| | | | | | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University
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Mathis T, Hofverberg P, Caujolle JP, Hérault J, Leal C, Maschi C, Delaunay B, Baillif S, Kodjikian L, Thariat J. Occurrence of Phosphenes in Patients Undergoing Proton Beam Therapy for Ocular Tumor. Am J Ophthalmol 2018; 192:31-38. [PMID: 29753854 DOI: 10.1016/j.ajo.2018.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/06/2018] [Accepted: 05/02/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE Phosphenes are frequently reported by patients irradiated in the head and neck area. The aim of the present study was to characterize and investigate potential mechanisms of proton beam therapy (PBT)-induced phosphenes in a large population of patients undergoing PBT for ocular tumors. DESIGN Prospective cohort study. METHODS Consecutive patients who underwent PBT in a single center were included. Immediately after the first session, all patients completed a questionnaire collecting information about the presence of phosphenes as well as their color, shape, and duration. Patient, tumor and treatment characteristics (dose volume histograms) were also collected. RESULTS Among the 474 patients included, 62.8% reported phosphenes during the first session of PBT. Reported colors were mainly blue-violet (70.5%) and white (14.1%). The prevalence of phosphenes was higher in younger patients (P = .003); other patient or ocular characteristics were not associated with the occurrence of phosphenes. Irradiation of the macula (P < .001) and/or optic disc (P < .001) were significantly associated with the presence of phosphenes, whereas blue-violet color was only associated with young age and irradiation of macular area (P = .04). Pupillary constriction was reported for 57.1% of patients with phosphenes vs 18.5% of patients without (P < .001). Blue-violet phosphenes (P < .001) and irradiation of macula (P = .001) were statistically associated with pupillary constriction. CONCLUSIONS The present study reported a high rate of phosphenes in patients irradiated by PBT for ocular tumor. Their blue-violet color and their association with a pupillary constriction probably indicates the stimulation of S-cones and retinal ganglion cells that reflects the activation of the afferent visual pathway.
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Affiliation(s)
- Thibaud Mathis
- Department of Ophthalmology, Croix-Rousse University Hospital, Hospices Civils de Lyon, Lyon, France; UMR-CNRS 5510 Matéis, Villeurbane, France.
| | - Petter Hofverberg
- Department of Radiation Therapy, Proton Therapy Center, Centre Antoine Lacassagne, Nice, France
| | | | - Joël Hérault
- Department of Radiation Therapy, Proton Therapy Center, Centre Antoine Lacassagne, Nice, France
| | - Cécilia Leal
- Department of Ophthalmology, Pasteur II Hospital, Nice, France
| | - Celia Maschi
- Department of Ophthalmology, Pasteur II Hospital, Nice, France
| | - Benoit Delaunay
- Department of Ophthalmology, Croix-Rousse University Hospital, Hospices Civils de Lyon, Lyon, France
| | | | - Laurent Kodjikian
- Department of Ophthalmology, Croix-Rousse University Hospital, Hospices Civils de Lyon, Lyon, France; UMR-CNRS 5510 Matéis, Villeurbane, France
| | - Juliette Thariat
- Department of Radiation Therapy, Centre François Baclesse - ARCHADE, Unicaen - Normandie University, Caen, France
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Chow SL, Page RL, Depre C. Role of ivabradine and heart rate lowering in chronic heart failure: guideline update. Expert Rev Cardiovasc Ther 2018; 16:515-526. [PMID: 29902387 DOI: 10.1080/14779072.2018.1489235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION This review summarizes the current management of heart failure (HF) in patients with reduced ejection fraction and the potential role of heart rate lowering agents in select populations, as recommended in the updated guidelines. Areas covered: PubMed was searched for studies that evaluated the role of heart rate lowering or ivabradine in HF management. Expert commentary: Targeting heart rate may offer benefit when added to renin-angiotensin aldosterone antagonists, and beta-blockers. Ivabradine is a heart rate lowering agent that acts on the funny current (If) in the sinoatrial node, thereby reducing heart rate without directly affecting cardiac contraction and relaxation. Clinical data from a phase III trial demonstrated that ivabradine reduced the composite end point of cardiovascular death or hospital admission for worsening systolic HF, while maintaining an acceptable safety profile in patients receiving standard of care therapy. These data, in addition to more recently published guidelines, suggest ivabradine as a promising new treatment option for lowering heart rate after optimizing standard therapy in select patients with chronic HF.
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Affiliation(s)
- Sheryl L Chow
- a Department of Pharmacy , Western University of Health Sciences , Pomona , CA , USA
| | - Robert L Page
- b Department of Clinical Pharmacy , University of Colorado , Denver , CO , USA
| | - Christophe Depre
- c Clinical Research Medical Director , Amgen Inc ., Thousand Oaks , CA , USA
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Giraldo Herrera CE. Shamanic Microscopy: Cellular Souls, Microbial Spirits. ANTHROPOLOGY OF CONSCIOUSNESS 2018. [DOI: 10.1111/anoc.12087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Role of the Funny Current Inhibitor Ivabradine in Cardiac Pharmacotherapy: A Systematic Review. Am J Ther 2018; 25:e247-e266. [DOI: 10.1097/mjt.0000000000000388] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
OBJECTIVE Ivabradine is a selective and specific inhibitor of the I(f) current in the sinoatrial and atrioventricular nodes. It decreases heart rate and myocardial oxygen consumption at rest and during exercise. It is used in adults for management of heart failure and angina, but promising results have been obtained in postural orthostatic tachycardia syndrome (POTS). There is little experience of ivabradine in childhood, although it is used on a compassionate basis. Our aim was to review our experience of ivabradine in a retrospective evaluation of pediatric patients with POTS. METHODS We evaluated all patients younger than 18 years for whom ivabradine had been prescribed for this indication, from February 2008 to June 2014. RESULTS Twenty-two patients were identified (15 female). Median age was 14.5 years (11-17 years). The ivabradine dosage after up-titration was 0.1 mg/kg per dose twice daily. In 15 (68%) symptoms improved. Ivabradine was suspended in five, but only in one for worsening of symptoms. There was a reduction in heart rate on resting electrocardiogram (EKG) from a mean (standard deviation) of 82.5 (13.6) bpm to a mean of 71 (16.5) bpm (p = 0.007). No patient had increased duration of QTc (p = 0.44). One (4.5%) experienced phosphenes. CONCLUSIONS From this initial experience, ivabradine is safe in patients younger than 18 years with POTS. We observed improvement of symptoms in 68% and phosphenes in less than 5%. Further studies are needed to assess the safety in a randomized control setting.
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Császár N, Scholkmann F, Salari V, Szőke H, Bókkon I. Phosphene perception is due to the ultra-weak photon emission produced in various parts of the visual system: glutamate in the focus. Rev Neurosci 2018; 27:291-9. [PMID: 26544101 DOI: 10.1515/revneuro-2015-0039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/11/2015] [Indexed: 12/24/2022]
Abstract
Phosphenes are experienced sensations of light, when there is no light causing them. The physiological processes underlying this phenomenon are still not well understood. Previously, we proposed a novel biopsychophysical approach concerning the cause of phosphenes based on the assumption that cellular endogenous ultra-weak photon emission (UPE) is the biophysical cause leading to the sensation of phosphenes. Briefly summarized, the visual sensation of light (phosphenes) is likely to be due to the inherent perception of UPE of cells in the visual system. If the intensity of spontaneous or induced photon emission of cells in the visual system exceeds a distinct threshold, it is hypothesized that it can become a conscious light sensation. Discussing several new and previous experiments, we point out that the UPE theory of phosphenes should be really considered as a scientifically appropriate and provable mechanism to explain the physiological basis of phosphenes. In the present paper, we also present our idea that some experiments may support that the cortical phosphene lights are due to the glutamate-related excess UPE in the occipital cortex.
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Sartiani L, Mannaioni G, Masi A, Novella Romanelli M, Cerbai E. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels. Pharmacol Rev 2017; 69:354-395. [PMID: 28878030 DOI: 10.1124/pr.117.014035] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.
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Affiliation(s)
- Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Alessio Masi
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
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Salari V, Scholkmann F, Vimal RLP, Császár N, Aslani M, Bókkon I. Phosphenes, retinal discrete dark noise, negative afterimages and retinogeniculate projections: A new explanatory framework based on endogenous ocular luminescence. Prog Retin Eye Res 2017; 60:101-119. [DOI: 10.1016/j.preteyeres.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/13/2017] [Accepted: 07/15/2017] [Indexed: 02/07/2023]
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Mathis T, Vignot S, Leal C, Caujolle JP, Maschi C, Mauget-Faÿsse M, Kodjikian L, Baillif S, Herault J, Thariat J. Mechanisms of phosphenes in irradiated patients. Oncotarget 2017; 8:64579-64590. [PMID: 28969095 PMCID: PMC5610027 DOI: 10.18632/oncotarget.18719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/15/2017] [Indexed: 11/25/2022] Open
Abstract
Anomalous visual perceptions have been reported in various diseases of the retina and visual pathways or can be experienced under specific conditions in healthy individuals. Phosphenes are perceptions of light in the absence of ambient light, occurring independently of the physiological and classical photonic stimulation of the retina. They are a frequent symptom in patients irradiated in the region of the central nervous system (CNS), head and neck and the eyes. Phosphenes have historically been attributed to complex physical phenomena such as Cherenkov radiation. While phosphenes are related to Cherenkov radiation under high energy photon/electron irradiation conditions, physical phenomena are unlikely to be responsible for light flashes at energies used for ocular proton therapy. Phosphenes may involve a direct role for ocular photoreceptors and possible interactions between cones and rods. Other mechanisms involving the retinal ganglion cells or ultraweak biophoton emission and rhodopsin bleaching after exposure to free radicals are also likely to be involved. Despite their frequency as shown in our preliminary observations, phosphenes have been underreported probably because their mechanism and impact are poorly understood. Recently, phosphenes have been used to restore the vision and whether they might predict vision loss after therapeutic irradiation is a current field of investigation. We have reviewed and also investigated here the mechanisms related to the occurrence of phosphenes in irradiated patients and especially in patients irradiated by proton therapy for ocular tumors.
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Affiliation(s)
- Thibaud Mathis
- Department of Ophthalmology, Croix-Rousse University Hospital, 69004 Lyon, France
| | - Stephane Vignot
- Department of Medical Oncology, Jean Godinot Institute, 51100 Reims, France
| | - Cecila Leal
- Department of Ophthalmology, Pasteur II Hospital, 06000 Nice, France
| | | | - Celia Maschi
- Department of Ophthalmology, Pasteur II Hospital, 06000 Nice, France
| | | | - Laurent Kodjikian
- Department of Ophthalmology, Croix-Rousse University Hospital, 69004 Lyon, France
| | - Stéphanie Baillif
- Department of Ophthalmology, Pasteur II Hospital, 06000 Nice, France
| | - Joel Herault
- Proton Therapy Center, Université Nice Sophia Antipolis, 06200 Nice, France
| | - Juliette Thariat
- Proton Therapy Center, Université Nice Sophia Antipolis, 06200 Nice, France.,Department of Radiation Therapy, Centre Francois Baclesse, ARCHADE, 14000 Caen, France
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Banzrai C, Nodera H, Okada R, Higashi S, Osaki Y, Kaji R. Modification of multiple ion channel functions in vivo by pharmacological inhibition: observation by threshold tracking and modeling. THE JOURNAL OF MEDICAL INVESTIGATION 2017; 64:30-38. [PMID: 28373625 DOI: 10.2152/jmi.64.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Maintenance of axonal excitability relies on complex balance by multiple ion currents, but its evaluation is limited by in vitro single channel neurophysiological study on overall behavior. We sought to evaluate behaviors of multiple ion currents by pharmacological blockade. The threshold tracking technique was used to measure multiple excitability indices on tail sensory nerve of normal male mice before and after administration of either BaCl2 or ivabradine. Mathematical modeling was used to identify the interval changes of the channel parameters. After administration of BaCl2 and ivabradine, the following changes were present: greater threshold changes of both depolarizing and hyperpolarizing threshold electrotonus by both; additionally, reduced S2 accommodation, reduced late subexcitability and increased superexcitability by BaCl2, increased S3 accommodation by ivabradine. Mathematical modelling implied reduction of slow K+ conductance, along with reduction of H conductance (Ih) by BaCl2; and reduction of Ih while augmentation of K+ conductances by ivabradine. Pharmacological blockade of a selective ion channel may be compensated by other ion channels. Unintended effects by ion channel modification could be caused by secondary current alteration by multiple ion channels. J. Med. Invest. 64: 30-38, February, 2017.
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HCN2 ion channels: basic science opens up possibilities for therapeutic intervention in neuropathic pain. Biochem J 2016; 473:2717-36. [DOI: 10.1042/bcj20160287] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/18/2016] [Indexed: 01/22/2023]
Abstract
Nociception — the ability to detect painful stimuli — is an invaluable sense that warns against present or imminent damage. In patients with chronic pain, however, this warning signal persists in the absence of any genuine threat and affects all aspects of everyday life. Neuropathic pain, a form of chronic pain caused by damage to sensory nerves themselves, is dishearteningly refractory to drugs that may work in other types of pain and is a major unmet medical need begging for novel analgesics. Hyperpolarisation-activated cyclic nucleotide (HCN)-modulated ion channels are best known for their fundamental pacemaker role in the heart; here, we review data demonstrating that the HCN2 isoform acts in an analogous way as a ‘pacemaker for pain’, in that its activity in nociceptive neurons is critical for the maintenance of electrical activity and for the sensation of chronic pain in pathological pain states. Pharmacological block or genetic deletion of HCN2 in sensory neurons provides robust pain relief in a variety of animal models of inflammatory and neuropathic pain, without any effect on normal sensation of acute pain. We discuss the implications of these findings for our understanding of neuropathic pain pathogenesis, and we outline possible future opportunities for the development of efficacious and safe pharmacotherapies in a range of chronic pain syndromes.
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Weeda ER, Nguyen E, White CM. Role of Ivabradine in the Treatment of Patients With Cardiovascular Disease. Ann Pharmacother 2016; 50:475-85. [PMID: 26917820 DOI: 10.1177/1060028016631571] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE To review the role of heart rate in myocardial ischemia and heart failure with reduced ejection fraction (HFrEF) as well as ivabradine's pharmacology and pharmacokinetics, clinical trials, and place in therapy. DATA SOURCES We conducted MEDLINE searches from 1980 to October 2015 using the terms heart failure, HFrEF, angina, f-channel inhibitor, and ivabradine, with forward and backward citation tracking. STUDY SELECTION AND DATA EXTRACTION English-language trials assessing ivabradine were obtained. Studies and narrative reviews of the topic areas were incorporated if they provided relevant data to inform the practicing clinician. DATA SYNTHESIS In the SIGNIFY (Study Assessing the Morbidity-Mortality Benefits of the If Inhibitor Ivabradine in Patients with Coronary Artery Disease) trial, there was no difference in the primary composite end point of cardiovascular (CV) mortality or nonfatal myocardial infarction with ivabradine use in patients with stable coronary artery disease (CAD) versus placebo (P = 0.20). In the subgroup with Canadian Cardiovascular Society angina class ≥II, there was an 18% increase in the primary end point with ivabradine versus placebo (P = 0.02). In HFrEF patients, ivabradine reduced CV mortality or heart failure hospitalizations versus placebo, as seen in the SHIFT (Systolic Heart failure treatment with the If inhibitor ivabradine Trial; P < 0.05). CONCLUSIONS The SIGNIFY trial negated much of the enthusiasm for using ivabradine in CAD. Ivabradine is a promising therapy in HFrEF based on the results of the SHIFT, but it is an adjunctive therapy, not a substitute for drugs with proven mortality benefits.
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Affiliation(s)
- Erin R Weeda
- University of Connecticut/Hartford Hospital, Storrs, CT, USA
| | - Elaine Nguyen
- University of Connecticut/Hartford Hospital, Storrs, CT, USA
| | - C Michael White
- University of Connecticut/Hartford Hospital, Storrs, CT, USA
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Schön C, Asteriti S, Koch S, Sothilingam V, Garrido MG, Tanimoto N, Herms J, Seeliger MW, Cangiano L, Biel M, Michalakis S. Loss of HCN1 enhances disease progression in mouse models of CNG channel-linked retinitis pigmentosa and achromatopsia. Hum Mol Genet 2016; 25:1165-75. [DOI: 10.1093/hmg/ddv639] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/22/2015] [Indexed: 01/24/2023] Open
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Nguyen E, Weeda ER, White CM. A Review of New Pharmacologic Treatments for Patients With Chronic Heart Failure With Reduced Ejection Fraction. J Clin Pharmacol 2015; 56:936-47. [PMID: 26626162 DOI: 10.1002/jcph.677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Heart failure (HF) impacts an estimated 5.7 million Americans, and its prevalence is projected to increase to more than 8 million Americans in the next 15 years. Key clinical trials have established an evidence-based foundation for treatment of heart failure with reduced ejection fraction (HFrEF). Ivabradine and sacubitril/valsartan, which inhibit the f-channel and the angiotensin receptor and neprilysin, respectively, were recently approved by the Food and Drug Administration for HFrEF. In systolic heart failure, treatment with the If inhibitor ivabradine significantly reduced the combined endpoint of cardiovascular mortality or heart failure hospital admission vs placebo (P < .05). In the Prospective Comparison of angiotensin receptor-neprilysin inhibitor (ARNI) with angiotensin-converting enzyme inhibitor (ACEI) to Determine Impact on Global Mortality and Morbidity in Heart Failure trial, sacubitril/valsartan significantly reduced the combined endpoint of cardiovascular death or heart failure hospitalization vs enalapril (P < .001). The place of therapy with ivabradine and sacubitril/valsartan is defined by these trials and their interplay with guideline-directed medical therapy. Ivabradine and sacubitril/valsartan increase pharmacotherapy options for the treatment of HFrEF but are not yet first-line agents. Clinical application will be better defined in the coming years as practitioners increase their familiarity with ivabradine and sacubitril/valsartan.
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Affiliation(s)
- Elaine Nguyen
- University of Connecticut School of Pharmacy, Hartford Hospital Divisions of Cardiology and Pharmacy, Storrs, CT, USA
| | - Erin R Weeda
- University of Connecticut School of Pharmacy, Hartford Hospital Divisions of Cardiology and Pharmacy, Storrs, CT, USA
| | - C Michael White
- University of Connecticut School of Pharmacy, Hartford Hospital Divisions of Cardiology and Pharmacy, Storrs, CT, USA
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Herrmann S, Schnorr S, Ludwig A. HCN channels--modulators of cardiac and neuronal excitability. Int J Mol Sci 2015; 16:1429-47. [PMID: 25580535 PMCID: PMC4307311 DOI: 10.3390/ijms16011429] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/31/2014] [Indexed: 01/06/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1-4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides and the modulation by tyrosine phosphorylation. The four isoforms are differentially expressed in various excitable tissues. This review will mainly focus on recent insights into the functional role of the channels apart from their classic role as pacemakers. The importance of HCN channels in the cardiac ventricle and ventricular hypertrophy will be discussed. In addition, their functional significance in the peripheral nervous system and nociception will be examined. The data, which are mainly derived from studies using transgenic mice, suggest that HCN channels contribute significantly to cellular excitability in these tissues. Remarkably, the impact of the channels is clearly more pronounced in pathophysiological states including ventricular hypertrophy as well as neural inflammation and neuropathy suggesting that HCN channels may constitute promising drug targets in the treatment of these conditions. This perspective as well as the current therapeutic use of HCN blockers will also be addressed.
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Affiliation(s)
- Stefan Herrmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Sabine Schnorr
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
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Rushworth GF, Lambrakis P, Leslie SJ. Ivabradine: a new rate-limiting therapy for coronary artery disease and heart failure. Ther Adv Drug Saf 2014; 2:19-28. [PMID: 25083199 DOI: 10.1177/2042098610393209] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Ivabradine is a new bradycardic agent acting on the I f channels of sinoatrial nodal cells to decrease the rate of diastolic depolarization and thus heart rate. The benefit of ivabradine over other negatively chronotropic agents is its absence of negative inotropy. Effective management of coronary artery disease, in terms of reducing morbidity and mortality, is reliant on controlling heart rate. Ivabradine has been shown to safely and effectively reduce heart rate without compromising cardiac function in patients with coronary artery disease and more recently in patients with heart failure and raised heart rate. Furthermore, ivabradine has been shown to have a favourable side-effect profile compared with alternative bradycardic agents. This article reviews the evidence for ivabradine in coronary artery disease and heart failure and compares its safety with alternative bradycardic agents for these conditions.
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Affiliation(s)
- Gordon F Rushworth
- Advanced Pharmacist Clinical Research, Highland Clinical Research Facility, Centre for Health Science, Old Perth Road, Inverness, IV2 3JH UK
| | | | - Stephen J Leslie
- Consultant Cardiologist, Cardiac Unit, Raigmore Hospital, Inverness IV2 3UJ, UK and University of Stirling, Highland Campus, Old Perth Road, Inverness IV2 3JH, UK
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fMRI of retina-originated phosphenes experienced by patients with Leber congenital amaurosis. PLoS One 2014; 9:e86068. [PMID: 24465873 PMCID: PMC3897613 DOI: 10.1371/journal.pone.0086068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 12/05/2013] [Indexed: 11/19/2022] Open
Abstract
A phenomenon characterized by the experience of seeing light without any light actually entering the eye is called phosphenes or photopsias. Phosphenes can occur spontaneously or via induction by external stimuli. Previous reports regarding phosphenes have primarily focused on externally induced phosphenes such as by applying alternating or direct current to the cortex. A few of these reports used functional magnetic resonance (fMRI) to study activations induced by cortical phosphenes. However, there are no fMRI reports on spontaneous phosphenes originating from the retina and the resulting pattern of cortical activations. We performed fMRI during a reversing checkerboard paradigm in three LCA patients who underwent unilateral gene therapy and reported experiencing frequent phosphene on a daily basis. We observed bilateral cortical activation covering the entire visual cortices when patients reported experiencing phosphenes. In contrast, in the absence of phosphenes, activation was regulated by patient's visual ability and demonstrated improved cortical activation due to gene therapy. These fMRI results illustrate the potential impact of phosphene perception on visual function and they may explain some of the variability that clinicians find in visual function testing in retinal degeneration. Although we did not perform correlations between visual function and phosphenes, we hope data presented here raises awareness of this phenomenon and its potential effect on visual function and the implications for clinical testing. We recommend a thorough history for phosphene experiences be taken in patients with retinal disease who are candidates for gene or molecular therapy. Lastly, these data illustrate the potential power of fMRI as an outcome measure of gene therapy and the negative impact phosphenes may have on vision testing. fMRI has proven to be a sensitive, non-invasive, and reproducible test paradigm for these purposes and can complement standard visual function testing.
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Rosa GM, Ferrero S, Ghione P, Valbusa A, Brunelli C. An evaluation of the pharmacokinetics and pharmacodynamics of ivabradine for the treatment of heart failure. Expert Opin Drug Metab Toxicol 2013; 10:279-91. [PMID: 24377458 DOI: 10.1517/17425255.2014.876005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Ivabradine is a new heart-rate-lowering drug; the aim of this review was to analyze its role in heart failure (HF). AREAS COVERED This systematic review on the role of ivabradine in HF is based on material searched and obtained through Pubmed and Medline up to September 2013. EXPERT OPINION Heart rate (HR) is a risk factor in patients with HF, and its reduction is considered an important goal of therapy. The BEAUTIFUL trial demonstrated the benefits of ivabradine on prognosis (only on ischemic endpoints) in patients with coronary artery disease (CAD) and left ventricular systolic dysfunction (LVSD) and HR ≥ 60 bpm. In the SHIFT trial, which enrolled patients with LVSD, HF and HR ≥ 70 bpm, ivabradine administration (on top of guideline-based therapy, including β-blockers [BB]) was associated with a reduction of cardiovascular death and hospitalizations for HF, but BB were underutilized. Further studies are needed to test the efficacy of ivabradine in CAD patients with high HR and to shed light on the comparison between ivabradine and a more aggressive therapy with higher doses of BB in HF patients.
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Affiliation(s)
- Gian Marco Rosa
- University of Genoa, San Martino Hospital and National Institute for Cancer Research, Department of Cardiology , Genoa , Italy
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Bókkon I, Mallick BN, Tuszynski JA. Near death experiences: a multidisciplinary hypothesis. Front Hum Neurosci 2013; 7:533. [PMID: 24062655 PMCID: PMC3769617 DOI: 10.3389/fnhum.2013.00533] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 08/16/2013] [Indexed: 12/16/2022] Open
Abstract
Recently, we proposed a novel biophysical concept regarding on the appearance of brilliant lights during near death experiences (NDEs) (Bókkon and Salari, 2012). Specifically, perceiving brilliant light in NDEs has been proposed to arise due to the reperfusion that produces unregulated overproduction of free radicals and energetically excited molecules that can generate a transient enhancement of bioluminescent biophotons in different areas of the brain, including retinotopic visual areas. If this excess of bioluminescent photon emission exceeds a threshold in retinotopic visual areas, this can appear as (phosphene) lights because the brain interprets these intrinsic retinotopic bioluminescent photons as if they originated from the external physical world. Here, we review relevant literature that reported experimental studies (Imaizumi et al., 1984; Suzuki et al., 1985) that essentially support our previously published conception, i.e., that seeing lights in NDEs may be due to the transient enhancement of bioluminescent biophotons. Next, we briefly describe our biophysical visual representation model that may explain brilliant lights experienced during NDEs (by phosphenes as biophotons) and REM sleep associated dream-like intrinsic visual imageries through biophotons in NDEs. Finally, we link our biophysical visual representation notion to self-consciousness that may involve extremely low-energy quantum entanglements. This article is intended to introduce novel concepts for discussion and does not pretend to give the ultimate explanation for the currently unanswerable questions about matter, life and soul; their creation and their interrelationship.
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Affiliation(s)
- István Bókkon
- Neuroscience Department, Vision Research Institute Lowell, MA, USA
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Affiliation(s)
- François Roubille
- Montreal Heart Institute, 5000 Belanger St, Montreal, PQ H1T 1C8, QC, Canada
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Choi HY, Noh YH, Cho SH, Ghim JL, Choe S, Kim UJ, Ah Jung J, Bae KS, Lim HS. Evaluation of pharmacokinetic and pharmacodynamic profiles and tolerability after single (2.5, 5, or 10 mg) and repeated (2.5, 5, or 10 mg bid for 4.5 days) oral administration of ivabradine in healthy male Korean volunteers. Clin Ther 2013; 35:819-35. [PMID: 23755867 DOI: 10.1016/j.clinthera.2013.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/03/2013] [Accepted: 04/25/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Ivabradine, a selective inhibitor of the pacemaker current in the sinoatrial node, has shown pure heart rate (HR)-reducing effects with anti-ischemic efficacy as well as improvement in heart failure outcomes. OBJECTIVE The purpose of this study was to explore pharmacokinetic (PK) and pharmacodynamic (PD) characteristics and tolerability in healthy male Korean volunteers, as well as to compare them with PK/PD profiles of white subjects. METHODS This was a randomized, double-blind, placebo-controlled Phase I study conducted in healthy male subjects. For each of the 3 dosing groups, 9 subjects were randomized to receive ivabradine and 3 to receive placebo. Subjects received a single oral dose of ivabradine 2.5, 5, or 10 mg and after a 3-day washout period, repeat doses of 2.5, 5, or 10 mg BID for 4.5 days. Blood and urine samples were collected over 72 hours during each period, and levels of ivabradine and its metabolite S18982 were determined by using validated LC-MS/MS, followed by noncompartmental PK analysis. For PD properties and tolerability, 24-hour Holter recordings were obtained: at baseline, after a single dose, after repeated doses, and after the last dose. Serial resting 12-lead ECG assessments were also performed throughout the study. RESULTS Forty-eight subjects were enrolled, and 45 completed the study. After single doses of 2.5, 5, and 10 mg, respective mean Cmax levels of ivabradine were 9, 15, and 39 ng/mL, and mean AUC0-last values were 30, 52, and 121 ng h/mL. At steady state, mean Cmax,ss levels were 11, 19, and 42 ng/mL, reached at a median Tmax of 0.67 hour for all 3 doses. The mean AUC0-τ levels were 43, 58, and 139 ng h/mL, respectively. The PK findings were linear with dose and time. Decreases in mean HR on both the Holter recordings and ECGs were observed in all of the ivabradine groups compared with placebo. After the repeated doses, mean decreases in HR were greater than those for the single doses for the same period. Statistically significant differences were observed between the 5- and 10-mg ivabradine groups and placebo. A total of 3 adverse events were reported in 2 subjects receiving ivabradine; both fully recovered without sequelae. CONCLUSIONS Single and repeated administration of ivabradine were generally well tolerated in these healthy male Korean volunteers. Ivabradine induced significant reductions in HR, especially at doses of 5 and 10 mg. PK/PD characteristics were similar to those found in white subjects, suggesting that the dose concentration-response relationship of ivabradine is similar between Korean and white subjects.
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Affiliation(s)
- Hee Youn Choi
- Department of Clinical Pharmacology and Therapeutics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea
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Sprenger T, Supronsinchai W, Goadsby PJ. New onset migraine with aura after treatment initiation with ivabradine. J Headache Pain 2013; 14:45. [PMID: 23718730 PMCID: PMC3681602 DOI: 10.1186/1129-2377-14-45] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/26/2013] [Indexed: 11/21/2022] Open
Abstract
Background Migraine with aura is a complex neurological disorder modeled in animals by cortical spreading depression. It is less usual to find complete animal models for the disease so any opportunity to test a human effect back at the bench is welcome. Findings We report the case of a 24 year old woman who developed new onset episodic migraine with visual aura shortly after treatment initiation with the If ion channel blocker ivabradine for frequency control in hypertrophic cardiomyopathy. We studied whether ivabradine could alter cortical spreading depression in a suitable animal model. Sixteen rats received either ivabradine or saline, and the number of depolarization shifts and blood flow changes induced by cortical spreading depression were measured in both groups. No significant differences between the ivabradine and saline group were detected. Conclusions Ivabradine is an interesting substance since it is known to produce migraine-like phosphenes frequently and the patient we report developed de novo migraine with aura. However, we were unable to demonstrate that the drug influences the susceptibility of the brain to cortical spreading depression with acute administration. The combined data show the relationship of migraine aura to cortical spreading depression may have some nuances yet to be identified.
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Chaturvedi A, Singh Y, Chaturvedi H, Thawani V, Singla S, Parihar D. Comparison of the efficacy and tolerability of ivabradine and ranolazine in patients of chronic stable angina pectoris. J Pharmacol Pharmacother 2013; 4:33-8. [PMID: 23662022 PMCID: PMC3643340 DOI: 10.4103/0976-500x.107663] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Introduction: To compare the efficacy and tolerability of Ivabradine (IVA) and Ranolazine (RAN) in chronic angina patients. Materials and Methods: This was a follow-on, open-label trial conducted in a tertiary care hospital of Uttarakhand. Thirty patients each taking IVA 5 mg twice daily or RAN 500 mg twice daily were distributed to the respective groups. Patients were asked to fill a pretested questionnaire on frequency of anginal attacks and adverse reactions before and 2, 4 and 8 weeks after taking the respective medicines. Their blood pressure, heart rate and routine hematological and biochemical estimations were performed at baseline and after intervention. Results were statistically analyzed using different statistical tests, with P < 0.05 considered as significant. Results: There was no significant difference in the frequency of anginal attacks per week between the groups. The adverse drug reactions (ADRs) reported in the IVA group were dizziness (30%), headache (16.6%), backache (16.6%), vertigo (13.3%), blurred vision (13.3%), muscle cramps (10%), arthralgia (10%), cough and dyspnea (6.6%), hypersensitivity rash (6.6%), fever (3.3%) and nausea (3.3%). The ADRs in the RAN group were nausea (26.6%), dizziness (23.3%), vomiting (3.3%), constipation (3.3%) and vertigo (3.3%). The blood pressure, heart rate and routine hematological and biochemical evaluations did not show any significant difference in the pre–post values. IVA significantly decreased the resting heart rate after eight weeks of intervention. Conclusions: Both antianginal agents appeared equiactive. However, RAN had a better safety and tolerability profile than IVA. Serum sickness-like reaction was an adverse event noticed with IVA, which needs causality establishment.
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Affiliation(s)
- Aditi Chaturvedi
- Department of Pharmacology, Veer Chandra Singh Garhwali Government Medical Sciences and Research Institute, Srikot, Uttarakhand, India
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Tehovnik EJ, Slocum WM. Electrical induction of vision. Neurosci Biobehav Rev 2013; 37:803-18. [PMID: 23535445 DOI: 10.1016/j.neubiorev.2013.03.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 01/28/2013] [Accepted: 03/17/2013] [Indexed: 11/26/2022]
Abstract
We assess what monkeys see during electrical stimulation of primary visual cortex (area V1) and relate the findings to visual percepts evoked electrically from human V1. Discussed are: (1) the electrical, cytoarchitectonic, and visuo-behavioural factors that affect the ability of monkeys to detect currents in V1; (2) the methods used to ascertain what monkeys see when electrical stimulation is delivered to V1; (3) a corticofugal mechanism for the induction of visual percepts; and (4) the quantity of information transferred to V1 by electrical stimulation. Experiments are proposed that should advance our understanding of how electrical stimulation affects macaque and human V1. This work contributes to the development of a cortical visual prosthesis for the blind. We dedicate this work to the late Robert W. Doty.
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Riccioni G. Ivabradine: an intelligent drug for the treatment of ischemic heart disease. Molecules 2012; 17:13592-604. [PMID: 23159921 PMCID: PMC6268242 DOI: 10.3390/molecules171113592] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 12/13/2022] Open
Abstract
Heart rate (HR) is a precisely regulated variable, which plays a critical role in health and disease. Elevated resting HR is a significant predictor of all-cause and cardiovascular mortality in the general population and patients with cardiovascular disease (CVD). β-blocking drugs exert negative effects on regional myocardial blood flow and function when HR reduction is eliminated by atrial pacing; calcium channel antagonists (CCAs) functionally antagonize coronary vasoconstriction mediated through α-adreno-receptors and are thus devoid of this undesired effect, but the compounds are nevertheless negative inotropes. From these observations derives the necessity to find alternative, more selective drugs to reduce HR through inhibition of specific electrical current (I(f)). Ivabradine (IVA) is a novel specific HR-lowering agent that acts in sinus atrial node (SAN) cells by selectively inhibiting the pacemaker I(f) current in a dose-dependent manner by slowing the diastolic depolarization slope of SAN cells, and by reducing HR at rest during exercise in humans. Coronary artery diseases (CAD) represent the most common cause of death in middle-aged and older adults in European Countries. Most ischemic episodes are triggered by an increase in HR, that induces an imbalance between myocardial oxygen delivery and consumption. IVA, a selective and specific inhibitor of the I(f) current which reduced HR without adverse hemodynamic effects, has clearly and unequivocally demonstrated its efficacy in the treatment of chronic stable angina pectoris (CSAP) and myocardial ischemia with optimal tolerability profile due to selective interaction with I(f) channels. The aim of this review is to point out the usefulness of IVA in the treatment of ischemic heart disease.
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Affiliation(s)
- Graziano Riccioni
- Intensive Cardiology Care Unit, San Camillo de Lellis Hospital, Manfredonia, via Isonzo, 71043 Foggia, Italy.
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Del Lungo M, Melchiorre M, Guandalini L, Sartiani L, Mugelli A, Koncz I, Szel T, Varro A, Romanelli MN, Cerbai E. Novel blockers of hyperpolarization-activated current with isoform selectivity in recombinant cells and native tissue. Br J Pharmacol 2012; 166:602-16. [PMID: 22091830 DOI: 10.1111/j.1476-5381.2011.01782.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Selective hyperpolarization activated, cyclic nucleotide-gated channel (HCN) blockers represent an important therapeutic goal due to the wide distribution and multiple functions of these proteins, representing the molecular correlate of f- and h-current (I(f) or I(h) ). Recently, new compounds able to block differentially the homomeric HCN isoforms expressed in HEK293 have been synthesized. In the present work, the electrophysiological and pharmacological properties of these new HCN blockers were characterized and their activities evaluated on native channels. EXPERIMENTAL APPROACH HEK293 cells expressing mHCN1, mHCN2 and hHCN4 isoforms were used to verify channel blockade. Selected compounds were tested on native guinea pig sinoatrial node cells and neurons from mouse dorsal root ganglion (DRG) by patch-clamp recordings and on dog Purkinje fibres by intracellular recordings. KEY RESULTS In HEK293 cells, EC18 was found to be significantly selective for HCN4 and MEL57A for HCN1 at physiological membrane potential. When tested on guinea pig sinoatrial node cells, EC18 (10 µM) maintained its activity, reducing I(f) by 67% at -120 mV, while MEL57A (3 µM) reduced I(f) by 18%. In contrast, in mouse DRG neurons, only MEL57A (30 and 100 µM) significantly reduced I(h) by 60% at -80 mV. In dog cardiac Purkinje fibres, EC18, but not MEL57A, reduced the amplitude and slowed the slope of the spontaneous diastolic depolarization. CONCLUSIONS Our results have identified novel and highly selective HCN isoform blockers, EC18 and MEL57A; the selectivity found in recombinant system was maintained in various tissues expressing different HCN isoforms.
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Affiliation(s)
- Martina Del Lungo
- CIMMBA, Department of Pharmacology, University of Florence, Firenze, Italy Department of Pharmaceutical Sciences, University of Florence, Florence, Italy
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Ih current is necessary to maintain normal dopamine fluctuations and sleep consolidation in Drosophila. PLoS One 2012; 7:e36477. [PMID: 22574167 PMCID: PMC3344876 DOI: 10.1371/journal.pone.0036477] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 04/06/2012] [Indexed: 11/23/2022] Open
Abstract
HCN channels are becoming pharmacological targets mainly in cardiac diseases. But apart from their well-known role in heart pacemaking, these channels are widely expressed in the nervous system where they contribute to the neuron firing pattern. Consequently, abolishing Ih current might have detrimental consequences in a big repertoire of behavioral traits. Several studies in mammals have identified the Ih current as an important determinant of the firing activity of dopaminergic neurons, and recent evidences link alterations in this current to various dopamine-related disorders. We used the model organism Drosophila melanogaster to investigate how lack of Ih current affects dopamine levels and the behavioral consequences in the sleep∶activity pattern. Unlike mammals, in Drosophila there is only one gene encoding HCN channels. We generated a deficiency of the DmIh core gene region and measured, by HPLC, levels of dopamine. Our data demonstrate daily variations of dopamine in wild-type fly heads. Lack of Ih current dramatically alters dopamine pattern, but different mechanisms seem to operate during light and dark conditions. Behaviorally, DmIh mutant flies display alterations in the rest∶activity pattern, and altered circadian rhythms. Our data strongly suggest that Ih current is necessary to prevent dopamine overproduction at dark, while light input allows cycling of dopamine in an Ih current dependent manner. Moreover, lack of Ih current results in behavioral defects that are consistent with altered dopamine levels.
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Bókkon I, Salari V. Hypothesis about brilliant lights by bioluminescent photons in near death experiences. Med Hypotheses 2012; 79:47-9. [PMID: 22543076 DOI: 10.1016/j.mehy.2012.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 03/22/2012] [Accepted: 03/30/2012] [Indexed: 10/28/2022]
Abstract
In near death experiences (NDEs), seeing a brilliant light may arise in the recovery period following cardiac arrest, but the subjects can think that these experiences had happened during the actual period itself. Here we hypothesize a biophysical explanation about the encounter with a brilliant light in NDEs. Accordingly, meeting brilliant light in NDEs is due to the reperfusion that induces unregulated overproduction of free radicals and excited biomolecules among them in numerous parts in the visual system. Unregulated free radicals and excited species can produce a transient increase of bioluminescent photons in different areas of the visual system. If this excess of bioluminescent photon emission exceeds a threshold, they can appear as (phosphene) lights in our mind. In other words, seeing a brilliant light in NDEs may due to bioluminescent photons simultaneously generated in the recovery phase of numerous areas of the visual system and the brain interprets these intrinsic bioluminescent photons as if they were originated from the external visual world. Although our biophysical explanation about brilliant light phenomenon in NDEs can be promising, we do not reject further potential notions.
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Affiliation(s)
- István Bókkon
- Doctoral School of Pharmaceutical and Pharmacological Sciences, Semmelweis University, Hungary; Vision Research Institute, 25 Rita Street, Lowell, MA 01854, USA.
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Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels have a key role in the control of heart rate and neuronal excitability. Ivabradine is the first compound acting on HCN channels to be clinically approved for the treatment of angina pectoris. HCN channels may offer excellent opportunities for the development of novel anticonvulsant, anaesthetic and analgesic drugs. In support of this idea, some well-established drugs that act on the central nervous system - including lamotrigine, gabapentin and propofol - have been found to modulate HCN channel function. This Review gives an up-to-date summary of compounds acting on HCN channels, and discusses strategies to further explore the potential of these channels for therapeutic intervention.
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Abstract
Abstract: Pacemaking is a basic physiological process, and the cellular mechanisms involved in this function have always attracted the keen attention of investigators. The "funny" (I(f)) current, originally described in sinoatrial node myocytes as an inward current activated on hyperpolarization to the diastolic range of voltages, has properties suitable for generating repetitive activity and for modulating spontaneous rate. The degree of activation of the funny current determines, at the end of an action potential, the steepness of phase 4 depolarization; hence, the frequency of action potential firing. Because I(f) is controlled by intracellular cAMP and is thus activated and inhibited by beta-adrenergic and muscarinic M2 receptor stimulation, respectively, it represents a basic physiological mechanism mediating autonomic regulation of heart rate. Given the complexity of the cellular processes involved in rhythmic activity, an exact quantification of the extent to which I(f) and other mechanisms contribute to pacemaking is still a debated issue; nonetheless, a wealth of information collected since the current was first described more than 30 years ago clearly agrees to identify I(f) as a major player in both generation of spontaneous activity and rate control. I(f)- dependent pacemaking has recently advanced from a basic, physiologically relevant concept, as originally described, to a practical concept that has several potentially useful clinical applications and can be valuable in therapeutically relevant conditions. Typically, given their exclusive role in pacemaking, f-channels are ideal targets of drugs aiming to pharmacological control of cardiac rate. Molecules able to bind specifically to and block f-channels can thus be used as pharmacological tools for heart rate reduction with little or no adverse cardiovascular side effects. Indeed a selective f-channel inhibitor, ivabradine, is today commercially available as a tool in the treatment of stable chronic angina. Also, several loss-of-function mutations of HCN4 (hyperpolarization-activated, cyclic-nucleotide gated 4), the major constitutive subunit of f-channels in pacemaker cells, are known today to cause rhythm disturbances, such as for example inherited sinus bradycardia. Finally, gene- or cell-based methods for in situ delivery of f-channels to silent or defective cardiac muscle represent novel approaches for the development of biological pacemakers eventually able to replace electronic devices.
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Affiliation(s)
- Dario DiFrancesco
- University of Milano, Department of Biomolecular Sciences and Biotechnology, The PaceLab, via Celoria 26, 20133 Milano, Italy.
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