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Kapusniak A, Nath L, Hebart M, Franklin S. Heritability of sudden cardiac death in Thoroughbred racehorses. Equine Vet J 2024. [PMID: 38984817 DOI: 10.1111/evj.14130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 06/05/2024] [Indexed: 07/11/2024]
Abstract
BACKGROUND Sudden cardiac death (SCD) is an important cause of exercise-associated fatalities in Thoroughbred racehorses. Equine deaths share similarities with fatalities in human athletes that result from inherited cardiac disease. Whilst genetic causes have been postulated in horses, these have not been confirmed and heritability of SCD has not previously been estimated in Thoroughbred racehorses. OBJECTIVES To determine the heritability of SCD in a sample population of Thoroughbred racehorses. STUDY DESIGN Retrospective case-control study. METHODS Steward and post-mortem reports of Thoroughbred racehorses in Australia between 2007 and 2020 were reviewed to identify horses with SCD. Control horses were randomly selected from races in which SCD occurred or from races on the date of the case fatality. A five-generation integrated pedigree chart was collected for each horse. Estimates of heritability were obtained using an animal model in the ASReml-R program with variance components estimated assuming SCD was normally distributed, and on the logit transformed scale. Inbreeding coefficients were calculated and the risk of producing SCD-affected progeny was calculated for stallions that sired ≥5 individuals in the case-control population. RESULTS Ninety-three horses with SCD and 465 control horses were identified. Heritability on the underlying scale was 0.15 ± 0.09 (logit animal) and 0.24 ± 0.12 (normal animal). Inbreeding coefficients were not significantly different between groups. Of the 16 first generation sires that appeared ≥5 times in the case-control data set, two sires more frequently produced affected progeny (OR 7.95-10.41). MAIN LIMITATIONS Challenges in definitively confirming SCD may lead to misclassification of some cases. Some control horses may have not been exposed to environmental influences of SCD. Case numbers are low and the studied population may not represent the entire Thoroughbred genetic pool. CONCLUSION The heritability of SCD in this population was relatively low. However, individual stallions appear more likely to produce affected progeny. Further studies are required to understand the genetic and environmental influences that contribute to disease expression.
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Affiliation(s)
- Amie Kapusniak
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Laura Nath
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Michelle Hebart
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Samantha Franklin
- School of Animal & Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
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Vold VA, Glanville S, Klaerke DA, Pedersen PA. pXOOY: A dual-function vector for expression of membrane proteins in Saccharomyces cerevisiae and Xenopus laevis oocytes. PLoS One 2023; 18:e0281868. [PMID: 36809531 PMCID: PMC9942955 DOI: 10.1371/journal.pone.0281868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/02/2023] [Indexed: 02/23/2023] Open
Abstract
On the quest for solving structures of membrane proteins by X-ray crystallography or cryo-EM, large quantities of ultra-pure protein are a paramount prerequisite. Obtaining enough protein of such high standard is not a trivial task, especially for difficult-to-express membrane proteins. Producing membrane protein for structural studies is often performed in Escherichia coli or Saccharomyces cerevisiae and is frequently complemented with functional studies. Ion channels and electrogenic receptors are traditionally studied in terms of their electrophysiological behavior, which cannot be performed in neither E. coli nor yeast. Therefore, they are frequently characterized in mammalian cells or in Xenopus laevis oocytes. To avoid generating two different plasmids, we here describe the construction of a dual-function plasmid, pXOOY, for membrane protein production in yeast and for electrophysiology in oocytes. pXOOY was constructed such that all elements required for oocyte expression were copied from the dual Xenopus-mammalian vector pXOOM and meticulously introduced into the high-yield yeast expression vector pEMBLyex4. pXOOY is thus designed to preserve the high yield of protein from pEMBLyex4 while simultaneously permitting in vitro transcription for expression in oocytes. We evaluated the performance of pXOOY by comparing expression of two yeast codon optimized human potassium channels, ohERG and ohSlick (Slo2.1) from pXOOY to expression of these channels obtained from the reference vectors pEMBLyex4 and pXOOM. Our proof-of-concept study indicates that accumulation in PAP1500 yeast cells was higher when the channels were expressed from pXOOY, which was verified both qualitatively and quantitatively. Two-electrode voltage clamp measurements in oocytes showed that the pXOOY constructs encoding ohERG and ohSlick gave currents with full preservation of electrophysiological characteristics. Our results show that it is possible to design a dual-function Xenopus-yeast vector without compromising expression in yeast and simultaneously maintaining channel activity in oocytes.
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Affiliation(s)
- Victoria Amstrup Vold
- Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Sebastian Glanville
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Dan Arne Klaerke
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
- * E-mail: (PAP); (DAK)
| | - Per Amstrup Pedersen
- Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
- * E-mail: (PAP); (DAK)
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Comparison of Sources and Methods for the Isolation of Equine Adipose Tissue-Derived Stromal/Stem Cells and Preliminary Results on Their Reaction to Incubation with 5-Azacytidine. Animals (Basel) 2022; 12:ani12162049. [PMID: 36009640 PMCID: PMC9404420 DOI: 10.3390/ani12162049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 08/04/2022] [Accepted: 08/08/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary The function of the equine heart is different from that in other species, and a species-specific in vitro model would simplify investigations in the field of equine cardiology. The recent advances in stem cell research and the availability of adipose tissue-derived stromal/stem cells (ASCs) could be a promising starting point for the development of such an in vitro model. In order to test the hypothesis that equine ASCs can be differentiated into cells resembling heart cells, we isolated ASCs from abdominal, retrobulbar, and subcutaneous adipose tissue after collagenase digestion or from direct cultivation of explants. Both techniques resulted in similar yields of cells displaying morphological, immunophenotypical, and molecular biological characteristics of mesenchymal stem cells. Abdominal adipose tissue was found to be most suitable for ASC isolation in equines. However, contrasting earlier studies performed with ASCs from other species, equine ASCs were refractory to 5-azacytidine-induced upregulation of markers characteristic for the differentiation into heart cells. Hence, further studies are required to establish equine cardiomyocyte induction. Abstract Physiological particularities of the equine heart justify the development of an in vitro model suitable for investigations of the species-specific equine cardiac electrophysiology. Adipose tissue-derived stromal/stem cells (ASCs) could be a promising starting point from which to develop such a cardiomyocyte (CM)-like cell model. Therefore, we compared abdominal, retrobulbar, and subcutaneous adipose tissue as sources for the isolation of ASCs applying two isolation methods: the collagenase digestion and direct explant culture. Abdominal adipose tissue was most suitable for the isolation of ASCs and both isolation methods resulted in comparable yields of CD45-/CD34-negative cells expressing the mesenchymal stem cell markers CD29, CD44, and CD90, as well as pluripotency markers, as determined by flow cytometry and real-time quantitative PCR. However, exposure of equine ASCs to 5-azacytidine (5-AZA), reportedly inducing CM differentiation from rats, rabbits, and human ASCs, was not successful in our study. More precisely, neither the early differentiation markers GATA4 and NKX2-5, nor the late CM differentiation markers TNNI3, MYH6, and MYH7 were upregulated in equine ASCs exposed to 10 µM 5-AZA for 48 h. Hence, further work focusing on the optimal conditions for CM differentiation of equine stem cells derived from adipose tissue, as well as possibly from other origins, are needed.
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Premont A, Saadeh K, Edling C, Lewis R, Marr CM, Jeevaratnam K. Cardiac ion channel expression in the equine model - In-silico prediction utilising RNA sequencing data from mixed tissue samples. Physiol Rep 2022; 10:e15273. [PMID: 35880716 PMCID: PMC9316921 DOI: 10.14814/phy2.15273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/19/2022] [Accepted: 04/03/2022] [Indexed: 06/15/2023] Open
Abstract
Understanding cardiomyocyte ion channel expression is crucial to understanding normal cardiac electrophysiology and underlying mechanisms of cardiac pathologies particularly arrhythmias. Hitherto, equine cardiac ion channel expression has rarely been investigated. Therefore, we aim to predict equine cardiac ion channel gene expression. Raw RNAseq data from normal horses from 9 datasets was retrieved from ArrayExpress and European Nucleotide Archive and reanalysed. The normalised (FPKM) read counts for a gene in a mix of tissue were hypothesised to be the average of the expected expression in each tissue weighted by the proportion of the tissue in the mix. The cardiac-specific expression was predicted by estimating the mean expression in each other tissues. To evaluate the performance of the model, predicted gene expression values were compared to the human cardiac gene expression. Cardiac-specific expression could be predicted for 91 ion channels including most expressed Na+ channels, K+ channels and Ca2+ -handling proteins. These revealed interesting differences from what would be expected based on human studies. These differences included predominance of NaV 1.4 rather than NaV 1.5 channel, and RYR1, SERCA1 and CASQ1 rather than RYR2, SERCA2, CASQ2 Ca2+ -handling proteins. Differences in channel expression not only implicate potentially different regulatory mechanisms but also pathological mechanisms of arrhythmogenesis.
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Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Khalil Saadeh
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
- School of Clinical MedicineUniversity of CambridgeCambridgeUK
| | - Charlotte Edling
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Rebecca Lewis
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
| | - Celia M. Marr
- Faculty of Health and Medical SciencesUniversity of SurreyGuildfordSurreyUK
- School of Clinical MedicineUniversity of CambridgeCambridgeUK
- Rossdales Equine Hospital and Diagnostic CentreExningSuffolkUK
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Premont A, Balthes S, Marr CM, Jeevaratnam K. Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation. Equine Vet J 2021; 54:262-282. [PMID: 34564902 DOI: 10.1111/evj.13518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/26/2022]
Abstract
Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.
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Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Samantha Balthes
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Celia M Marr
- Rossdales Equine Hospital and Diagnostic Centre, Newmarket, UK
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Trachsel DS, Calloe K, Mykkänen AK, Raistakka P, Anttila M, Fredholm M, Tala M, Lamminpää K, Klaerke DA, Buhl R. Exercise-Associated Sudden Death in Finnish Standardbred and Coldblooded Trotters - A Case Series With Pedigree Analysis. J Equine Vet Sci 2021; 104:103694. [PMID: 34416991 DOI: 10.1016/j.jevs.2021.103694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/30/2021] [Accepted: 06/19/2021] [Indexed: 10/21/2022]
Abstract
Exercise-associated sudden deaths (EASDs) are deaths occurring unexpectedly during or immediately after exercise. Sudden cardiac death (SCD) is one cause of EASD. Cardiac arrhythmias caused by genetic variants have been linked to SCD in humans. We hypothesize that genetic variants may be associated with SCD in animals, including horses. Genetic variants are transmitted to offspring and their frequency might increase within a family. Therefore, the frequency of such variants might increase with the inbreeding factor. Higher inbreeding could have a negative impact on racing performance. Pedigree data and career earnings from racehorses diagnosed with SCD between 2002 and 2017 were compared using non-parametric tests with 1) control horses that died due to catastrophic musculoskeletal injuries and 2) horses that raced during the same period without reported problems. Diagnosis of SCD was based on necropsy reports, including macroscopic and microscopic examinations. Death was registered in the study period for 61 horses. Eleven of these horses were excluded due to missing autopsy reports. In 25 cases, the diagnosis remained unknown and death was possibly caused by cardiac arrhythmia, in two cases cardiac disease was identified, in seven cases a rupture of a major vessel had occurred. In addition, 16 horses died or were euthanized due to severe musculoskeletal injuries. No significant differences in inbreeding coefficients or in career earnings were found between the groups or between horses with EASD compared with other horses racing during the same period. The study provides no evidence for increased inbreeding factor in Finnish racehorses with SCD.
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Affiliation(s)
- Dagmar S Trachsel
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark; Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
| | - Kirstine Calloe
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Anna K Mykkänen
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Pia Raistakka
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Marjukka Anttila
- Veterinary Bacteriology and Pathology Research Unit, Finnish Food Authority, Helsinki
| | - Merete Fredholm
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Martti Tala
- Suomen Hippos, the Finnish Trotting and Breeding Association
| | | | - Dan A Klaerke
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
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Trachsel DS, Calloe K, J Rgensen E, Lunddahl CS, Pedersen PJ, Kanters JRK, Klaerke DA, Buhl R. Evaluation of electrocardiographic repolarization parameters after administration of trimethoprim-sulfadiazine, detomidine, or their combination in horses. Am J Vet Res 2021; 82:207-217. [PMID: 33629897 DOI: 10.2460/ajvr.82.3.207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether administration of trimethoprim-sulfadiazine (TMS), detomidine (DET), or TMS plus DET would be associated with changes in ECG repolarization parameters in horses. ANIMALS 9 healthy adult horses. PROCEDURES Each horse received 4 treatments in a blinded, randomized, crossover study design as follows: TMS, 16 to 24 mg/kg, IV; DET, 0.015 to 0.02 mg/kg, IV; TMS plus DET; and saline (0.9% NaCl) solution. Surface ECG traces were obtained over 24 hours, and repolarization parameters were measured at predefined time points after each treatment and compared with a 2-way ANOVA for repeated measures. RESULTS Heart rate-corrected QT intervals (QTc) were significantly increased after administration of DET (mean ± SD difference in QTc, 36.57 ± 23.07 milliseconds; increase of 7%) and TMS plus DET (44.96 ± 29.16 milliseconds; increase of 9%), compared with baseline (before treatment) values and values after administration of saline solution. Saline solution and TMS alone did not affect QTc. CONCLUSIONS AND CLINICAL RELEVANCE Administration of DET or TMS plus DET was associated with a significant and possibly clinically relevant prolongation of QTc, with prolongation of 7% to 9%, a range that is considered as a risk factor for the development of cardiac arrhythmias in people. Results were unexpected because DET is considered to be a safe sedative for horses.
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Bumped Kinase Inhibitors as therapy for apicomplexan parasitic diseases: lessons learned. Int J Parasitol 2020; 50:413-422. [PMID: 32224121 DOI: 10.1016/j.ijpara.2020.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 11/24/2022]
Abstract
Bumped Kinase Inhibitors, targeting Calcium-dependent Protein Kinase 1 in apicomplexan parasites with a glycine gatekeeper, are promising new therapeutics for apicomplexan diseases. Here we will review advances, as well as challenges and lessons learned regarding efficacy, safety, and pharmacology that have shaped our selection of pre-clinical candidates.
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Saito K, Abe N, Toyama H, Ejima Y, Yamauchi M, Mushiake H, Kazama I. Second-Generation Histamine H1 Receptor Antagonists Suppress Delayed Rectifier K +-Channel Currents in Murine Thymocytes. BIOMED RESEARCH INTERNATIONAL 2019; 2019:6261951. [PMID: 31183371 PMCID: PMC6515180 DOI: 10.1155/2019/6261951] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/31/2019] [Accepted: 04/18/2019] [Indexed: 01/31/2023]
Abstract
BACKGROUND/AIMS Voltage-dependent potassium channels (Kv1.3) are predominantly expressed in lymphocyte plasma membranes. These channels are critical for the activation and proliferation of lymphocytes. Since second-generation antihistamines are lipophilic and exert immunomodulatory effects, they are thought to affect the lymphocyte Kv1.3-channel currents. METHODS Using the patch-clamp whole-cell recording technique in murine thymocytes, we tested the effects of second-generation antihistamines, such as cetirizine, fexofenadine, azelastine, and terfenadine, on the channel currents and the membrane capacitance. RESULTS These drugs suppressed the peak and the pulse-end currents of the channels, although the effects of azelastine and terfenadine on the peak currents were more marked than those of cetirizine and fexofenadine. Both azelastine and terfenadine significantly lowered the membrane capacitance. Since these drugs did not affect the process of endocytosis in lymphocytes, they were thought to have interacted directly with the plasma membranes. CONCLUSIONS Our study revealed for the first time that second-generation antihistamines, including cetirizine, fexofenadine, azelastine, and terfenadine, exert suppressive effects on lymphocyte Kv1.3-channels. The efficacy of these drugs may be related to their immunomodulatory mechanisms that reduce the synthesis of inflammatory cytokine.
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Affiliation(s)
- Kazutomo Saito
- Department of Anesthesiology, Tohoku University Hospital, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Nozomu Abe
- Department of Anesthesiology, Tohoku University Hospital, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Hiroaki Toyama
- Department of Anesthesiology, Tohoku University Hospital, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Yutaka Ejima
- Department of Anesthesiology, Tohoku University Hospital, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Masanori Yamauchi
- Department of Anesthesiology, Tohoku University Hospital, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Hajime Mushiake
- Department of Physiology, Tohoku University Graduate School of Medicine, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
| | - Itsuro Kazama
- Department of Physiology, Tohoku University Graduate School of Medicine, Seiryo-cho, Aoba-ku, Sendai, Miyagi, Japan
- Miyagi University, School of Nursing, Gakuen, Taiwa-cho, Kurokawa-gun, Miyagi, Japan
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Antiarrhythmic Effects of Combining Dofetilide and Ranolazine in a Model of Acutely Induced Atrial Fibrillation in Horses. J Cardiovasc Pharmacol 2019; 71:26-35. [PMID: 29068807 PMCID: PMC5768216 DOI: 10.1097/fjc.0000000000000541] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Supplemental Digital Content is Available in the Text. Background: Antiarrhythmic compounds against atrial fibrillation (AF) often have reduced efficacy and may display cardiac and/or noncardiac toxicity. Efficacy can be improved by combining 2 compounds with distinct mechanisms, and it may be possible to use lower doses of each compound, thereby reducing the likelihood of adverse side effects. The purpose of this study was to investigate whether the effective doses of dofetilide and ranolazine can be reduced if the drugs are combined. Methods: Dofetilide, ranolazine, and a combination of these were administered in 4 incremental dosing regimens to horses with acutely pacing-induced AF. Time to cardioversion, atrial effective refractory period, and AF vulnerability and duration were assessed. Results: Of 8 horses, 6 cardioverted to sinus rhythm after infusion with a combination of 0.889 μg/kg dofetilide and 0.104 mg/kg ranolazine. Two horses cardioverted with 0.104 mg/kg ranolazine alone, and 3 cardioverted with 0.889 μg/kg dofetilide alone. The combination therapy decreased AF vulnerability (P < 0.05) and AF duration (P < 0.05). No change in atrial effective refractory period was detected with any of the drugs. Conclusions: The combination of dofetilide and ranolazine showed increased antiarrhythmic effects on acutely induced AF in horses, affecting time to cardioversion, AF vulnerability, and AF duration.
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Compounds commonly used in equine medicine inhibits the voltage-gated potassium channel K v11.1. Res Vet Sci 2019; 123:239-246. [PMID: 30685649 DOI: 10.1016/j.rvsc.2019.01.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 12/19/2018] [Accepted: 01/08/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUND The voltage-gated K+-channel Kv11.1 has a central role in cardiac repolarization. Blockage of Kv11.1 has been linked to severe cardiovascular side effects, such as acquired long QT syndrome (aLQTS), torsade de pointes arrhythmia and sudden cardiac death (SCD). Kv11.1 is susceptible to unspecific drug interactions due to the presence of two aromatic amino acids residing in the inner vestibule of the pore. These aromatic residues are also present in the equine orthologue of Kv11.1. This suggests that equine Kv11.1 may also be prone to high-affinity block by a range of different chemical entities, which potentially could cause severe cardiac side effects and SCD in horses. AIM To screen a series of commonly used drugs in equine medicine for interaction with Kv11.1. METHODS High-throughput screening of selected compounds on human Kv11.1 expressed in a mammalian cell line was performed using an automated patch clamp system, the SyncroPatch 384PE (Nanion Technologies, Munich, Germany). Results were validated on equine Kv11.1 expressed in CHO-K1 cells by manual patch clamp. RESULTS Acepromazine maleat (IC50 = 0.5 μM) trimethoprim (IC50 = 100 μM), diphenhydramine hydrochloride (IC50 = 2 μM) and cyproheptadine hydrochloride (IC50 = 1.84 μM) inhibited equine Kv11.1 current at clinically relevant drug concentrations. CONCLUSION The results suggest that drug interaction with Kv11.1 can occur in horses and that some drugs potentially may induce repolarization disorders in horses.
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Calloe K. Doctoral Dissertation: The transient outward potassium current in healthy and diseased hearts. Acta Physiol (Oxf) 2019; 225 Suppl 717:e13225. [PMID: 30628199 DOI: 10.1111/apha.13225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Kirstine Calloe
- Section for Anatomy; Biochemistry and Physiology; Department for Veterinary and Animal Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg C Denmark
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Trachsel DS, Tejada MA, Groesfjeld Christensen V, Pedersen PJ, Kanters JK, Buhl R, Calloe K, Klaerke DA. Effects of trimethoprim-sulfadiazine and detomidine on the function of equine Kv
11.1 channels in a two-electrode voltage-clamp (TEVC) oocyte model. J Vet Pharmacol Ther 2018; 41:536-545. [DOI: 10.1111/jvp.12502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/22/2018] [Indexed: 02/03/2023]
Affiliation(s)
- D. S. Trachsel
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
- Department of Veterinary Clinical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Taastrup Denmark
| | - M. A. Tejada
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
| | - V. Groesfjeld Christensen
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
| | - P. J. Pedersen
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
| | - J. K. Kanters
- Laboratory of Experimental Cardiology; Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - R. Buhl
- Department of Veterinary Clinical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Taastrup Denmark
| | - K. Calloe
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
| | - D. A. Klaerke
- Department of Veterinary and Animal Science; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg Denmark
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In vitro growth inhibition of Theileria equi by bumped kinase inhibitors. Vet Parasitol 2018; 251:90-94. [PMID: 29426483 DOI: 10.1016/j.vetpar.2017.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 11/20/2017] [Accepted: 12/31/2017] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Theileria equi, an etiologic agent of equine piroplasmosis, is a tick-transmitted hemoprotozoan of the phylum Apicomplexa. Recent outbreaks of piroplasmosis in the United States have renewed interest in safe and effective treatment options. Although imidocarb dipropionate (IMD) is the drug of choice for clearance of T. equi, adverse reactions and recently documented resistance support the need for alternative therapeutic strategies. The recently described bumped kinase inhibitors (BKIs) are a new class of compounds that could potentially be used as safe and effective alternatives to IMD. In an initial effort to evaluate this potential, herein we determined the T. equi growth inhibitory activity of 11 BKIs relative to that of IMD and the previously tested BKI 1294. Because some BKIs have known human ether-à-go-go related gene (hERG) channel activity, we also assessed the hERG activity of each compound with the goal to identify those with the highest potency against T. equi coupled with the lowest potential for cardiotoxicity. RESULTS Six BKIs inhibited T. equi growth in vitro, including the previously evaluated BKI 1294 which was used as a positive control. All six compounds were significantly less potent (higher 50% effective concentration (EC50)) than IMD. Two of those compounds were more potent than BKI 1294 control but had similar hERG activity. Although the remaining three compounds had similar to lower potency than BKI 1294, hERG EC50 was higher for three of them (BKI 1735, BKI 1369 and BKI 1318). CONCLUSIONS The BKI compounds evaluated in this study inhibited T. equi in vitro and had diverse hERG activity. Based on these considerations, three compounds would be suitable for further evaluation. While these results provide a foundation for future work, in vivo pharmacokinetic, pharmacodynamics, and safety studies are needed before BKI compounds can be recommended for clinical use in T. equi infected horses.
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Jeevaratnam K, Chadda KR, Salvage SC, Valli H, Ahmad S, Grace AA, Huang CLH. Ion channels, long QT syndrome and arrhythmogenesis in ageing. Clin Exp Pharmacol Physiol 2017; 44 Suppl 1:38-45. [PMID: 28024120 PMCID: PMC5763326 DOI: 10.1111/1440-1681.12721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/18/2016] [Accepted: 12/19/2016] [Indexed: 01/08/2023]
Abstract
Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency. Previous reviews have explored the relationships between age and loss-of-function Nav 1.5 mutations in producing arrhythmogenicity. The present review now explores complementary relationships arising from gain-of-function Nav 1.5 mutations associated with long QT3 (LQTS3). LQTS3 patients show increased risks of life-threatening ventricular arrhythmias, particularly after 40 years of age, consistent with such interactions between the ion channel abnormailities and ageing. In turn clinical evidence suggests that ageing is accompanied by structural, particularly fibrotic, as well as electrophysiological change. These abnormalities may result from biochemical changes producing low-grade inflammation resulting from increased production of reactive oxygen species and superoxide. Experimental studies offer further insights into the underlying mechanisms underlying these phenotypes. Thus, studies in genetically modified murine models for LQTS implicated action potential recovery processes in arrhythmogenesis resulting from functional ion channel abnormalities. In addition, ageing wild type (WT) murine models demonstrated both ion channel alterations and fibrotic changes with ageing. Murine models then suggested evidence for interactions between ageing and ion channel mutations and provided insights into potential arrhythmic mechanisms inviting future exploration.
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Affiliation(s)
- Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.,School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.,Physiological Laboratory, University of Cambridge, Cambridge, UK
| | | | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Andrew A Grace
- Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, UK
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Pedersen PJ, Thomsen KB, Flak JB, Tejada MA, Hauser F, Trachsel D, Buhl R, Kalbfleisch T, DePriest MS, MacLeod JN, Calloe K, Klaerke DA. Molecular cloning and functional expression of the K + channel K V7.1 and the regulatory subunit KCNE1 from equine myocardium. Res Vet Sci 2017; 113:79-86. [PMID: 28917093 DOI: 10.1016/j.rvsc.2017.09.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 08/05/2017] [Accepted: 09/07/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND The voltage-gated K+-channel KV7.1 and the subunit KCNE1, encoded by the KCNQ1 and KCNE1 genes, respectively, are responsible for termination of the cardiac action potential. In humans, mutations in these genes can predispose patients to arrhythmias and sudden cardiac death (SCD). AIM To characterize equine KV7.1/KCNE1 currents and compare them to human KV7.1/KCNE1 currents to determine whether KV7.1/KCNE1 plays a similar role in equine and human hearts. METHODS mRNA encoding KV7.1 and KCNE1 was isolated from equine hearts, sequenced, and cloned into expression vectors. The channel subunits were heterologously expressed in Xenopus laevis oocytes or CHO-K1 cells and characterized using voltage-clamp techniques. RESULTS Equine KV7.1/KCNE1 expressed in CHO-K1 cells exhibited electrophysiological properties that are overall similar to the human orthologs; however, a slower deactivation was found which could result in more open channels at fast rates. CONCLUSION The results suggest that the equine KV7.1/KCNE1 channel may be important for cardiac repolarization and this could indicate that horses are susceptible to SCD caused by mutations in KCNQ1 and KCNE1.
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Affiliation(s)
- Philip J Pedersen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Kirsten B Thomsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Jon B Flak
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Maria A Tejada
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Frank Hauser
- Center for Functional and Comparative Insect Genomics, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Dagmar Trachsel
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Theodore Kalbfleisch
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Louisville, Louisville, KY, United States
| | - Michael Scott DePriest
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Louisville, Louisville, KY, United States
| | - James N MacLeod
- Maxwell H., Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, United States
| | - Kirstine Calloe
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
| | - Dan A Klaerke
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
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Van Voorhis WC, Doggett JS, Parsons M, Hulverson MA, Choi R, Arnold SLM, Riggs MW, Hemphill A, Howe DK, Mealey RH, Lau AOT, Merritt EA, Maly DJ, Fan E, Ojo KK. Extended-spectrum antiprotozoal bumped kinase inhibitors: A review. Exp Parasitol 2017; 180:71-83. [PMID: 28065755 DOI: 10.1016/j.exppara.2017.01.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/02/2017] [Accepted: 01/04/2017] [Indexed: 01/08/2023]
Abstract
Many life-cycle processes in parasites are regulated by protein phosphorylation. Hence, disruption of essential protein kinase function has been explored for therapy of parasitic diseases. However, the difficulty of inhibiting parasite protein kinases to the exclusion of host orthologues poses a practical challenge. A possible path around this difficulty is the use of bumped kinase inhibitors for targeting calcium-dependent protein kinases that contain atypically small gatekeeper residues and are crucial for pathogenic apicomplexan parasites' survival and proliferation. In this article, we review efficacy against the kinase target, parasite growth in vitro, and in animal infection models, as well as the relevant pharmacokinetic and safety parameters of bumped kinase inhibitors.
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Affiliation(s)
- Wesley C Van Voorhis
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
| | | | - Marilyn Parsons
- Department of Global Health, University of Washington, Seattle, WA 98195, USA; Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Matthew A Hulverson
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, USA
| | - Ryan Choi
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, USA
| | - Samuel L M Arnold
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, USA
| | - Michael W Riggs
- School of Animal and Comparative Biomedical Sciences, College of Agriculture and Life Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Berne, Switzerland
| | - Daniel K Howe
- Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA
| | - Robert H Mealey
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7040, USA
| | - Audrey O T Lau
- The National Institutes of Health, NIAID, DEA, 5601 Fishers Lane, Rockville, MD 20892, USA
| | - Ethan A Merritt
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Dustin J Maly
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Kayode K Ojo
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Diseases (CERID), University of Washington, Seattle, WA 98109, USA.
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