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Ríos E, Samsó M, Figueroa LC, Manno C, Tammineni ER, Rios Giordano L, Riazi S. Artificial intelligence approaches to the volumetric quantification of glycogen granules in EM images of human tissue. J Gen Physiol 2024; 156:e202413595. [PMID: 38980209 PMCID: PMC11233403 DOI: 10.1085/jgp.202413595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/12/2024] [Accepted: 06/13/2024] [Indexed: 07/10/2024] Open
Abstract
Skeletal muscle, the major processor of dietary glucose, stores it in myriad glycogen granules. Their numbers vary with cellular location and physiological and pathophysiological states. AI models were developed to derive granular glycogen content from electron-microscopic images of human muscle. Two UNet-type semantic segmentation models were built: "Locations" classified pixels as belonging to different regions in the cell; "Granules" identified pixels within granules. From their joint output, a pixel fraction pf was calculated for images from patients positive (MHS) or negative (MHN) to a test for malignant hyperthermia susceptibility. pf was used to derive vf, the volume fraction occupied by granules. The relationship vf (pf) was derived from a simulation of volumes ("baskets") containing virtual granules at realistic concentrations. The simulated granules had diameters matching the real ones, which were measured by adapting a utility devised for calcium sparks. Applying this relationship to the pf measured in images, vf was calculated for every region and patient, and from them a glycogen concentration. The intermyofibrillar spaces and the sarcomeric I band had the highest granular content. The measured glycogen concentration was low enough to allow for a substantial presence of non-granular glycogen. The MHS samples had an approximately threefold lower concentration (significant in a hierarchical test), consistent with earlier evidence of diminished glucose processing in MHS. The AI models and the approach to infer three-dimensional magnitudes from two-dimensional images should be adaptable to other tasks on a variety of images from patients and animal models and different disease conditions.
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Affiliation(s)
- Eduardo Ríos
- Department of Physiology and Biophysics, Rush University, Chicago, IL, USA
| | - Montserrat Samsó
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Lourdes C Figueroa
- Department of Physiology and Biophysics, Rush University, Chicago, IL, USA
| | - Carlo Manno
- Department of Physiology and Biophysics, Rush University, Chicago, IL, USA
| | - Eshwar R Tammineni
- Department of Physiology and Biophysics, Rush University, Chicago, IL, USA
| | | | - Sheila Riazi
- Department of Anesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
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Ibarra Moreno CA, Silva HCA, Voermans NC, Jungbluth H, van den Bersselaar LR, Rendu J, Cieniewicz A, Hopkins PM, Riazi S. Myopathic manifestations across the adult lifespan of patients with malignant hyperthermia susceptibility: a narrative review. Br J Anaesth 2024:S0007-0912(24)00419-7. [PMID: 39107166 DOI: 10.1016/j.bja.2024.05.046] [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: 02/17/2024] [Revised: 05/27/2024] [Accepted: 05/29/2024] [Indexed: 08/09/2024] Open
Abstract
Malignant hyperthermia susceptibility (MHS) designates individuals at risk of developing a hypermetabolic reaction triggered by halogenated anaesthetics or the depolarising neuromuscular blocking agent suxamethonium. Over the past few decades, beyond the operating theatre, myopathic manifestations impacting daily life are increasingly recognised as a prevalent phenomenon in MHS patients. At the request of the European Malignant Hyperthermia Group, we reviewed the literature and gathered the opinion of experts to define MHS-related myopathy as a distinct phenotype expressed across the adult lifespan of MHS patients unrelated to anaesthetic exposure; this serves to raise awareness about non-anaesthetic manifestations, potential therapies, and management of MHS-related myopathy. We focused on the clinical presentation, biochemical and histopathological findings, and the impact on patient well-being. The spectrum of symptoms of MHS-related myopathy encompasses muscle cramps, stiffness, myalgias, rhabdomyolysis, and weakness, with a wide age range of onset mainly during adulthood. Histopathological analysis can reveal nonspecific abnormalities suggestive of RYR1 involvement, while metabolic profiling reflects altered energy metabolism in MHS muscle. Myopathic manifestations can significantly impact patient quality of life and lead to functional limitations and socio-economic burden. While currently available therapies can provide symptomatic relief, there is a need for further research into targeted treatments addressing the underlying pathophysiology. Counselling early after establishing the MHS diagnosis, followed by multidisciplinary management involving various medical specialties, is crucial to optimise patient care.
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Affiliation(s)
- Carlos A Ibarra Moreno
- Malignant Hyperthermia Investigation Unit, Department of Anesthesiology and Pain Management, University Health Network, Toronto, ON, Canada
| | - Helga C A Silva
- Malignant Hyperthermia Unit, Department of Anesthesiology, Pain and Intensive Care, Federal University of São Paulo, São Paulo, Brazil
| | - Nicol C Voermans
- Department of Neurology, Radboudumc Research Institute for Medical Innovation, Nijmegen, The Netherlands
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina London Children's Hospital, Guy's and St. Thomas' Hospital NHS Foundation Trust, London, UK; Randall Centre for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College London, London, UK
| | - Luuk R van den Bersselaar
- Malignant Hyperthermia Investigation Unit, Department of Anesthesiology, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands; Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - John Rendu
- Universite Grenoble Alpes, INSERM, Grenoble Institut Neurosciences, U1216, CHU Grenoble Alpes, Grenoble, France
| | - Agnieszka Cieniewicz
- Department of Anaesthesiology and Intensive Therapy, Institute of Tuberculosis and Lung Diseases, Warsaw, Poland
| | - Philip M Hopkins
- Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK; Department of Anaesthesia, St James's University Hospital, Leeds Teaching Hospitals, NHS Trust, Leeds, UK
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesiology and Pain Management, University Health Network, Toronto, ON, Canada.
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Cong Z, Wan T, Wang J, Feng L, Cao C, Li Z, Wang X, Han Y, Zhou Y, Gao Y, Zhang J, Qu Y, Guo X. Epidemiological and clinical features of malignant hyperthermia: A scoping review. Clin Genet 2024; 105:233-242. [PMID: 38148504 DOI: 10.1111/cge.14475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/22/2023] [Accepted: 12/07/2023] [Indexed: 12/28/2023]
Abstract
Malignant hyperthermia (MH) is a potentially fatal inherited pharmacogenetic disorder related to pathogenic variants in the RYR1, CACNA1S, or STAC3 genes. Early recognition of the occurrence of MH and prompt medical treatment are indispensable to ensure a positive outcome. The purpose of this study was to provide valuable information for the early identification of MH by summarizing epidemiological and clinical features of MH. This scoping review followed the methodological framework recommended by Arksey and O'Malley. PubMed, Embase, and Web of science databases were searched for studies that evaluated the epidemical and clinical characteristics of MH. A total of 37 studies were included in this review, of which 26 were related to epidemiology and 24 were associated with clinical characteristics. The morbidity of MH varied from 0.18 per 100 000 to 3.9 per 100 000. The mortality was within the range of 0%-18.2%. Identified risk factors included sex, age, disorders associated with MH, and others. The most frequent initial clinical signs included hyperthermia, sinus tachycardia, and hypercarbia. The occurrence of certain signs, such as hypercapnia, delayed first temperature measurement, and peak temperature were associated with poor outcomes. The epidemiological and clinical features of MH varied considerably and some risk factors and typical clinical signs were identified. The main limitation of this review is that the treatment and management strategies were not assessed sufficiently due to limited information.
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Affiliation(s)
- Zhukai Cong
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Tingting Wan
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Jiechu Wang
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Luyang Feng
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Cathy Cao
- Department of Anesthesiology, MedStar Washington Hospital Center, Washington, DC, USA
| | - Zhengqian Li
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Xiaoxiao Wang
- Research Center for Clinical Epidemiology, Peking University Third Hospital, Beijing, China
| | - Yongzheng Han
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Yang Zhou
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Ya Gao
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Jing Zhang
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Yinyin Qu
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
| | - Xiangyang Guo
- Department of Anesthesiology, Peking University Third Hospital, Beijing, China
- Beijing Center of Quality Control and lmprovement on Clinical Anesthesia, Beijing, China
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Figueroa L, Kraeva N, Manno C, Ibarra-Moreno CA, Tammineni ER, Riazi S, Rios E. Distinct pathophysiological characteristics in developing muscle from patients susceptible to malignant hyperthermia. Br J Anaesth 2023; 131:47-55. [PMID: 36792386 PMCID: PMC10308439 DOI: 10.1016/j.bja.2023.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 12/19/2022] [Accepted: 01/02/2023] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND Most patients with malignant hyperthermia susceptibility diagnosed by the in vitro caffeine-halothane contracture test (CHCT) develop excessive force in response to halothane but not caffeine (halothane-hypersensitive). Hallmarks of halothane-hypersensitive patients include high incidence of musculoskeletal symptoms at rest and abnormal calcium events in muscle. By measuring sensitivity to halothane of myotubes and extending clinical observations and cell-level studies to a large group of patients, we reach new insights into the pathological mechanism of malignant hyperthermia susceptibility. METHODS Patients with malignant hyperthermia susceptibility were classified into subgroups HH and HS (positive to halothane only and positive to both caffeine and halothane). The effects on [Ca2+]cyto of halothane concentrations between 0.5 and 3 % were measured in myotubes and compared with CHCT responses of muscle. A clinical index that summarises patient symptoms was determined for 67 patients, together with a calcium index summarising resting [Ca2+]cyto and spontaneous and electrically evoked Ca2+ events in their primary myotubes. RESULTS Halothane-hypersensitive myotubes showed a higher response to halothane 0.5% than the caffeine-halothane hypersensitive myotubes (P<0.001), but a lower response to higher concentrations, comparable with that used in the CHCT (P=0.055). The HH group had a higher calcium index (P<0.001), but their clinical index was not significantly elevated vs the HS. Principal component analysis identified electrically evoked Ca2+ spikes and resting [Ca2+]cyto as the strongest variables for separation of subgroups. CONCLUSIONS Enhanced sensitivity to depolarisation and to halothane appear to be the primary, mutually reinforcing and phenotype-defining defects of halothane-hypersensitive patients with malignant hyperthermia susceptibility.
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Affiliation(s)
- Lourdes Figueroa
- Department of Physiology and Biophysics, Rush University Medical Centre, Chicago, IL, USA.
| | - Natalia Kraeva
- Malignant Hyperthermia Unit, Department of Anaesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Carlo Manno
- Department of Physiology and Biophysics, Rush University Medical Centre, Chicago, IL, USA
| | - Carlos A Ibarra-Moreno
- Malignant Hyperthermia Unit, Department of Anaesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Eshwar R Tammineni
- Department of Physiology and Biophysics, Rush University Medical Centre, Chicago, IL, USA
| | - Sheila Riazi
- Malignant Hyperthermia Unit, Department of Anaesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Eduardo Rios
- Department of Physiology and Biophysics, Rush University Medical Centre, Chicago, IL, USA
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Hopkins PM. What is malignant hyperthermia susceptibility? Br J Anaesth 2023:S0007-0912(23)00189-7. [PMID: 37198032 DOI: 10.1016/j.bja.2023.04.014] [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: 03/01/2023] [Revised: 04/07/2023] [Accepted: 04/17/2023] [Indexed: 05/19/2023] Open
Abstract
The molecular mechanisms of susceptibility to malignant hyperthermia are complex. The malignant hyperthermia susceptibility phenotype should be reserved for patients who have a personal or family history consistent with malignant hyperthermia under anaesthesia and are subsequently demonstrated through diagnostic testing to be at risk.
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Affiliation(s)
- Philip M Hopkins
- Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK; Malignant Hyperthermia Investigation Unit, Department of Anaesthesia, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
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Moreno CAI, Kraeva N, Zvaritch E, Jungbluth H, Voermans NC, Riazi S. Oral Dantrolene for Myopathic Symptoms in Malignant Hyperthermia-Susceptible Patients: A 25-Year Retrospective Cohort Study of Adverse Effects and Tolerability. Anesth Analg 2023; 136:569-577. [PMID: 36201369 PMCID: PMC9974786 DOI: 10.1213/ane.0000000000006207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Patients susceptible to malignant hyperthermia (MH) may experience disabling manifestations of an unspecified myopathy outside the context of anesthesia, including myalgia, fatigue, or episodic rhabdomyolysis. Clinical observations suggest that oral dantrolene may relief myopathic symptoms in MH-susceptible (MHS) patients. However, high-dose oral dantrolene has been associated with severe hepatotoxicity. METHODS In a retrospective database review (1994-2018), we investigated a cohort of patients who were diagnosed as MHS by a positive caffeine-halothane contracture test (CHCT), had myopathic manifestations, and received oral dantrolene. Our aim was to investigate the occurrence of serious adverse effects and the adherence to oral dantrolene therapy. We also explored factors associated with self-reported clinical improvement, considering as nonresponders patients with intolerable adverse effects or who reported no improvement 8 weeks after starting treatment. RESULTS Among 476 MHS patients with positive CHCT, 193 had muscle symptoms, 164 started oral dantrolene, 27 refused treatment, and 2 were excluded due to abnormal liver function before starting therapy. There were no serious adverse effects reported. Forty-six of 164 patients (28%; 95% confidence interval [CI], 22%-35%) experienced mild to moderate adverse effects. Twenty-two patients (22/164, 13%; 95% CI, 9%-19%) discontinued treatment, among which 16 due to adverse effects and 6 due to lack of improvement. One hundred forty-two patients (87%; 95% CI, 80%-90%) adhered to therapy and reported improvement of myalgia (n = 78), fatigue (n = 32), or rhabdomyolysis/hiperCKemia (n = 32). The proportion of responders was larger among patients with MH history than among those referred due to a clinical myopathy with nonpertinent anesthetic history (97% vs 79%, respectively; 95% CI of the difference, 8.5-28; P < .001). Patients with a sarcoplasmic reticulum Ca2+ release channel ryanodine receptor gene ( RYR1 ) variant had higher odds of responding to dantrolene treatment (OR, 6.4; 95% CI, 1.3-30.9; P = .013). Dantrolene median dose was 50 (25-400) and 200 (25-400) mg·day -1 in responders and nonresponders, respectively. CONCLUSIONS We found that oral dantrolene produced no serious adverse effects within the reported dose range, and was well tolerated by most MH-susceptible patients presenting myopathic symptoms. Our study provides dosing and adverse effect data as a basis for further randomized controlled clinical trials to determine the efficacy of oral dantrolene for symptomatic relief in MHS-related myopathies.
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Affiliation(s)
- Carlos A. Ibarra Moreno
- Department of Anesthesiology and Pain Medicine, Malignant Hyperthermia Investigation Unit, Toronto General Hospital–University Health Network, Toronto, Ontario, Canada
| | - Natalia Kraeva
- Department of Anesthesiology and Pain Medicine, Malignant Hyperthermia Investigation Unit, Toronto General Hospital–University Health Network, Toronto, Ontario, Canada
| | - Elena Zvaritch
- Department of Anesthesiology and Pain Medicine, Malignant Hyperthermia Investigation Unit, Toronto General Hospital–University Health Network, Toronto, Ontario, Canada
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children’s Hospital, Guy’s and St Thomas’ Hospital NHS Foundation Trust, London, United Kingdom, Randall Centre for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine, King’s College, London, United Kingdom
| | - Nicol C. Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Sheila Riazi
- Department of Anesthesiology and Pain Medicine, Malignant Hyperthermia Investigation Unit, Toronto General Hospital–University Health Network, Toronto, Ontario, Canada
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de Mello JM, Andrade PV, Santos JM, Oliveira ASB, Vainzof M, do Amaral JLG, Almeida da Silva HC. Predictive factors of the contracture test for diagnosing malignant hyperthermia in a Brazilian population sample: a retrospective observational study. BRAZILIAN JOURNAL OF ANESTHESIOLOGY (ELSEVIER) 2023; 73:145-152. [PMID: 35835312 PMCID: PMC10068564 DOI: 10.1016/j.bjane.2022.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 06/01/2022] [Accepted: 06/03/2022] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Malignant Hyperthermia (MH) is a pharmacogenetic, hereditary and autosomal dominant syndrome triggered by halogenates/succinylcholine. The In Vitro Contracture Test (IVCT) is the gold standard diagnostic test for MH, and it evaluates abnormal skeletal muscle reactions of susceptible individuals (earlier/greater contracture) when exposed to caffeine/halothane. MH susceptibility episodes and IVCT seem to be related to individual features. OBJECTIVE To assess variables that correlate with IVCT in Brazilian patients referred for MH investigation due to a history of personal/family MH. METHODS We examined IVCTs of 80 patients investigated for MH between 2004‒2019. We recorded clinical data (age, sex, presence of muscle weakness or myopathy with muscle biopsy showing cores, genetic evaluation, IVCT result) and IVCT features (initial and final maximum contraction, caffeine/halothane concentration triggering contracture of 0.2g, contracture at caffeine concentration of 2 and 32 mmoL and at 2% halothane, and contraction after 100 Hz stimulation). RESULTS Mean age of the sample was 35±13.3 years, and most of the subjects were female (n=43 or 54%) and MH susceptible (60%). Of the 20 subjects undergoing genetic investigation, 65% showed variants in RYR1/CACNA1S genes. We found no difference between the positive and negative IVCT groups regarding age, sex, number of probands, presence of muscle weakness or myopathy with muscle biopsy showing cores. Regression analysis revealed that the best predictors of positive IVCT were male sex (+12%), absence of muscle weakness (+20%), and personal MH background (+17%). CONCLUSIONS Positive IVCT results have been correlated to male probands, in accordance with early publications. Furthermore, normal muscle strength has been confirmed as a significant predictor of positive IVCT while investigating suspected MH cases.
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Affiliation(s)
- Jean Marcel de Mello
- Universidade Federal de São Paulo, Escola Paulista de Medicina, Centro de Hipertermia Maligna, Disciplina de Anestesiologia, Dor e Terapia Intensiva, São Paulo, SP, Brazil
| | - Pamela Vieira Andrade
- Universidade Federal de São Paulo, Escola Paulista de Medicina, Centro de Hipertermia Maligna, Disciplina de Anestesiologia, Dor e Terapia Intensiva, São Paulo, SP, Brazil
| | - Joilson Moura Santos
- Universidade Federal de São Paulo, Escola Paulista de Medicina, Centro de Hipertermia Maligna, Disciplina de Anestesiologia, Dor e Terapia Intensiva, São Paulo, SP, Brazil
| | | | - Mariz Vainzof
- Universidade de São Paulo, Instituto de Biociências, Departamento de Genética e Biologia Evolutiva, São Paulo, SP, Brazil
| | - José Luiz Gomes do Amaral
- Universidade Federal de São Paulo, Escola Paulista de Medicina, Centro de Hipertermia Maligna, Disciplina de Anestesiologia, Dor e Terapia Intensiva, São Paulo, SP, Brazil
| | - Helga Cristina Almeida da Silva
- Universidade Federal de São Paulo, Escola Paulista de Medicina, Centro de Hipertermia Maligna, Disciplina de Anestesiologia, Dor e Terapia Intensiva, São Paulo, SP, Brazil.
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Tammineni ER, Figueroa L, Manno C, Varma D, Kraeva N, Ibarra CA, Klip A, Riazi S, Rios E. Muscle calcium stress cleaves junctophilin1, unleashing a gene regulatory program predicted to correct glucose dysregulation. eLife 2023; 12:e78874. [PMID: 36724092 PMCID: PMC9891728 DOI: 10.7554/elife.78874] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 01/11/2023] [Indexed: 02/02/2023] Open
Abstract
Calcium ion movements between cellular stores and the cytosol govern muscle contraction, the most energy-consuming function in mammals, which confers skeletal myofibers a pivotal role in glycemia regulation. Chronic myoplasmic calcium elevation ("calcium stress"), found in malignant hyperthermia-susceptible (MHS) patients and multiple myopathies, has been suggested to underlie the progression from hyperglycemia to insulin resistance. What drives such progression remains elusive. We find that muscle cells derived from MHS patients have increased content of an activated fragment of GSK3β - a specialized kinase that inhibits glycogen synthase, impairing glucose utilization and delineating a path to hyperglycemia. We also find decreased content of junctophilin1, an essential structural protein that colocalizes in the couplon with the voltage-sensing CaV1.1, the calcium channel RyR1 and calpain1, accompanied by an increase in a 44 kDa junctophilin1 fragment (JPh44) that moves into nuclei. We trace these changes to activated proteolysis by calpain1, secondary to increased myoplasmic calcium. We demonstrate that a JPh44-like construct induces transcriptional changes predictive of increased glucose utilization in myoblasts, including less transcription and translation of GSK3β and decreased transcription of proteins that reduce utilization of glucose. These effects reveal a stress-adaptive response, mediated by the novel regulator of transcription JPh44.
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Affiliation(s)
- Eshwar R Tammineni
- Department of Physiology and Biophysics, Rush UniversityChicagoUnited States
| | - Lourdes Figueroa
- Department of Physiology and Biophysics, Rush UniversityChicagoUnited States
| | - Carlo Manno
- Department of Physiology and Biophysics, Rush UniversityChicagoUnited States
| | - Disha Varma
- Department of Internal Medicine, Division of Nephrology, Rush UniversityChicagoUnited States
| | - Natalia Kraeva
- Department of Anesthesia & Pain Management, University of TorontoTorontoCanada
| | - Carlos A Ibarra
- Department of Anesthesia & Pain Management, University of TorontoTorontoCanada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick ChildrenTorontoCanada
| | - Sheila Riazi
- Department of Anesthesia & Pain Management, University of TorontoTorontoCanada
| | - Eduardo Rios
- Department of Physiology and Biophysics, Rush UniversityChicagoUnited States
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van den Bersselaar LR, Jungbluth H, Kruijt N, Kamsteeg EJ, Fernandez-Garcia MA, Treves S, Riazi S, Malagon I, van Eijk LT, van Alfen N, van Engelen BGM, Scheffer GJ, Snoeck MMJ, Voermans NC. Neuromuscular symptoms in patients with RYR1-related malignant hyperthermia and rhabdomyolysis. Brain Commun 2022; 4:fcac292. [PMID: 36751502 PMCID: PMC9897183 DOI: 10.1093/braincomms/fcac292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/21/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
Malignant hyperthermia and exertional rhabdomyolysis have conventionally been considered episodic phenotypes that occur in otherwise healthy individuals in response to an external trigger. However, recent studies have demonstrated a clinical and histopathological continuum between patients with a history of malignant hyperthermia susceptibility and/or exertional rhabdomyolysis and RYR1-related congenital myopathies. We hypothesize that patients with a history of RYR1-related exertional rhabdomyolysis or malignant hyperthermia susceptibility do have permanent neuromuscular symptoms between malignant hyperthermia or exertional rhabdomyolysis episodes. We performed a prospective cross-sectional observational clinical study of neuromuscular features in patients with a history of RYR1-related exertional rhabdomyolysis and/or malignant hyperthermia susceptibility (n = 40) compared with healthy controls (n = 80). Patients with an RYR1-related congenital myopathy, manifesting as muscle weakness preceding other symptoms as well as other (neuromuscular) diseases resulting in muscle weakness were excluded. Study procedures included a standardized history of neuromuscular symptoms, a review of all relevant ancillary diagnostic tests performed up to the point of inclusion and a comprehensive, standardized neuromuscular assessment. Results of the standardized neuromuscular history were compared with healthy controls. Results of the neuromuscular assessment were compared with validated reference values. The proportion of patients suffering from cramps (P < 0.001), myalgia (P < 0.001) and exertional myalgia (P < 0.001) was higher compared with healthy controls. Healthcare professionals were consulted because of apparent neuromuscular symptoms by 17/40 (42.5%) patients and 7/80 (8.8%) healthy controls (P < 0.001). Apart from elevated creatine kinase levels in 19/40 (47.5%) patients and mild abnormalities on muscle biopsies identified in 13/16 (81.3%), ancillary investigations were normal in most patients. The Medical Research Council sum score, spirometry and results of functional measurements were also mostly normal. Three of 40 patients (7.5%) suffered from late-onset muscle weakness, most prominent in the proximal lower extremity muscles. Patients with RYR1 variants resulting in malignant hyperthermia susceptibility and/or exertional rhabdomyolysis frequently report additional neuromuscular symptoms such as myalgia and muscle cramps compared with healthy controls. These symptoms result in frequent consultation of healthcare professionals and sometimes in unnecessary invasive diagnostic procedures. Most patients do have normal strength at a younger age but may develop muscle weakness later in life.
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Affiliation(s)
- Luuk R van den Bersselaar
- Correspondence to: Luuk R van den Bersselaar Weg door Jonkerbos 100, 6532 SZ Nijmegen, The Netherlands E-mail:
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy’s and St Thomas’ Hospital NHS Foundation Trust, SE1 7EH London, UK,Randall Centre of Cell and Molecular Biophysics, Muscle Signaling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College, WC2R 2LS London, UK
| | - Nick Kruijt
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy’s and St Thomas’ Hospital NHS Foundation Trust, SE1 7EH London, UK
| | - Susan Treves
- Departments of Biomedicine and Neurology, Neuromuscular research Group, University Hospital Basel, 4031 Basel, Switzerland
| | - Sheila Riazi
- Department of Anesthesia, Malignant Hyperthermia Investigation Unit, University Health Network, University of Toronto, M5s 1a4 Toronto, Ontario, Canada
| | - Ignacio Malagon
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Lucas T van Eijk
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Nens van Alfen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Baziel G M van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Gert-Jan Scheffer
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
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10
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Ibarra Moreno CA, Kraeva N, Zvaritch E, Figueroa L, Rios E, Biesecker L, Van Petegem F, Hopkins PM, Riazi S. A multi-dimensional analysis of genotype-phenotype discordance in malignant hyperthermia susceptibility. Br J Anaesth 2020; 125:995-1001. [PMID: 32861507 PMCID: PMC7729844 DOI: 10.1016/j.bja.2020.07.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Malignant hyperthermia (MH) susceptibility is an inherited condition, diagnosed either by the presence of a pathogenic genetic variant or by in vitro caffeine-halothane contracture testing. Through a multi-dimensional approach, we describe the implications of discordance between genetic and in vitro test results in a patient with a family history of possible MH. METHODS The patient, whose brother had a possible MH reaction, underwent the caffeine-halothane contracture test (CHCT) according to the North American MH Group protocol. Screening of the complete RYR1 and CACNA1S transcripts was done using Sanger sequencing. Additional functional analyses included skinned myofibre calcium-induced calcium release sensitivity, calcium signalling assays in cultured myotubes, and in silico evaluation of the effect of any genetic variants on their chemical environment. RESULTS The patient's CHCT result was negative but she carried an RYR1 variant c.1209C>G, p.Ile403Met, that is listed as pathogenic by the European Malignant Hyperthermia Group. Functional tests indicated a gain-of-function effect with a weak impact, and the variant was predicted to affect the folding stability of the 3D structure of the RyR1 protein. Based on American College of Medical Genetics and Genomics/Association of Molecular Pathology guidelines, this variant would be characterised as a variant of uncertain significance. CONCLUSIONS Available data do not confirm or exclude an increased risk of MH for this patient. Further research is needed to correlate RyR1 functional assays, including the current gold standard testing for MH susceptibility, with clinical phenotypes. The pathogenicity of genetic variants associated with MH susceptibility should be re-evaluated.
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Affiliation(s)
- Carlos A Ibarra Moreno
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Natalia Kraeva
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Elena Zvaritch
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Lourdes Figueroa
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - Eduardo Rios
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - Leslie Biesecker
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Philip M Hopkins
- Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK; Department of Anaesthesia, St James's University Hospital, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia, University Health Network, University of Toronto, Toronto, ON, Canada.
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11
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T lymphocytes from malignant hyperthermia-susceptible mice display aberrations in intracellular calcium signaling and mitochondrial function. Cell Calcium 2020; 93:102325. [PMID: 33310301 DOI: 10.1016/j.ceca.2020.102325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/05/2023]
Abstract
Gain-of-function RyR1-p.R163C mutation in ryanodine receptors type 1 (RyR1) deregulates Ca2+ signaling and mitochondrial function in skeletal muscle and causes malignant hyperthermia in humans and mice under triggering conditions. We investigated whether T lymphocytes from heterozygous RyR1-p.R163C knock-in mutant mice (HET T cells) display measurable aberrations in resting cytosolic Ca2+ concentration ([Ca2+]i), Ca2+ release from the store, store-operated Ca2+ entry (SOCE), and mitochondrial inner membrane potential (ΔΨm) compared with T lymphocytes from wild-type mice (WT T cells). We explored whether these variables can be used to distinguish between T cells with normal and altered RyR1 genotype. HET and WT T cells were isolated from spleen and lymph nodes and activated in vitro using phytohemagglutinin P. [Ca2+]i and ΔΨm dynamics were examined using Fura 2 and tetramethylrhodamine methyl ester fluorescent dyes, respectively. Activated HET T cells displayed elevated resting [Ca2+]i, diminished responses to Ca2+ mobilization with thapsigargin, and decreased rate of [Ca2+]i elevation in response to SOCE compared with WT T cells. Pretreatment of HET T cells with ryanodine or dantrolene sodium reduced disparities in the resting [Ca2+]i and ability of thapsigargin to mobilize Ca2+ between HET and WT T cells. While SOCE elicited dissipation of the ΔΨm in WT T cells, it produced ΔΨm hyperpolarization in HET T cells. When used as the classification variable, the amplitude of thapsigargin-induced Ca2+ transient showed the best promise in predicting the presence of RyR1-p.R163C mutation. Other significant variables identified by machine learning analysis were the ratio of resting cytosolic Ca2+ level to the amplitude of thapsigargin-induced Ca2+ transient and an integral of changes in ΔΨm in response to SOCE. Our study demonstrated that gain-of-function mutation in RyR1 significantly affects Ca2+ signaling and mitochondrial fiction in T lymphocytes, which suggests that this mutation may cause altered immune responses in its carrier. Our data link the RyR1-p.R163C mutation, which causes inherited skeletal muscle diseases, to deregulation of Ca2+ signaling and mitochondrial function in immune T cells and establish proof-of-principle for in vitro T cell-based diagnostic assay for hereditary RyR1 hyperfunction.
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12
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Gonzalez A, Iles TL, Iaizzo PA, Bandschapp O. Impact of statin intake on malignant hyperthermia: an in vitro and in vivo swine study. BMC Anesthesiol 2020; 20:270. [PMID: 33096987 PMCID: PMC7585199 DOI: 10.1186/s12871-020-01186-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 10/13/2020] [Indexed: 01/24/2023] Open
Abstract
Background Statin intake is associated with muscular side effects, among which the unmasking of latent myopathies and of malignant hyperthermia (MH) susceptibility have been reported. These findings, together with experimental data in small animals, prompt speculation that statin therapy may compromise the performance of skeletal muscle during diagnostic in vitro contracture tests (IVCT). In addition, statins might reduce triggering thresholds in susceptible individuals (MHS), or exacerbate MH progression. We sought to obtain empirical data to address these questions. Methods We compared the responses of 3 different muscles from untreated or simvastatin treated MHS and non-susceptible (MHN) pigs. MHS animals were also invasively monitored for signs of impending MH during sevoflurane anesthesia. Results Muscles from statin treated MHS pigs responded with enhanced in vitro contractures to halothane, while responses to caffeine were unaltered by the treatment. Neither agent elicited contractures in muscles from statin treated MHN pigs. In vivo, end- tide pCO2, hemodynamic evolution, plasma pH, potassium and lactate concentrations consistently pointed to mild acceleration of MH development in statin-treated pigs, whereas masseter spasm and rigor faded compared to untreated MHS animals. Conclusions The diagnostic sensitivity and specificity of the IVCT remains unchanged by a short-term simvastatin treatment in MHS swine. Evidence of modest enhancement in cardiovascular and metabolic signs of MH, as well as masked pathognomonic muscle rigor observed under simvastatin therapy suggest a potentially misleading influence on the clinical presentation of MH. The findings deserve further study to include other statins and therapeutic regimes.
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Affiliation(s)
- Asensio Gonzalez
- Department for Anesthesia, Interdisciplinary Intermediate Care, Prehospital Emergency Medicine and Pain Therapy, University Hospital Basel, Spitalstrasse 21, CH-4031, Basel, Switzerland
| | - Tinen L Iles
- Department of Surgery and Integrative Biology and Physiology, Institute for Engineering in Medicine, University of Minnesota, Minneapolis, USA
| | - Paul A Iaizzo
- Department of Surgery and Integrative Biology and Physiology, Institute for Engineering in Medicine, University of Minnesota, Minneapolis, USA
| | - Oliver Bandschapp
- Department for Anesthesia, Interdisciplinary Intermediate Care, Prehospital Emergency Medicine and Pain Therapy, University Hospital Basel, Spitalstrasse 21, CH-4031, Basel, Switzerland.
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13
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Tammineni ER, Kraeva N, Figueroa L, Manno C, Ibarra CA, Klip A, Riazi S, Rios E. Intracellular calcium leak lowers glucose storage in human muscle, promoting hyperglycemia and diabetes. eLife 2020; 9:e53999. [PMID: 32364497 PMCID: PMC7282812 DOI: 10.7554/elife.53999] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 05/04/2020] [Indexed: 12/18/2022] Open
Abstract
Most glucose is processed in muscle, for energy or glycogen stores. Malignant Hyperthermia Susceptibility (MHS) exemplifies muscle conditions that increase [Ca2+]cytosol. 42% of MHS patients have hyperglycemia. We show that phosphorylated glycogen phosphorylase (GPa), glycogen synthase (GSa) - respectively activated and inactivated by phosphorylation - and their Ca2+-dependent kinase (PhK), are elevated in microsomal extracts from MHS patients' muscle. Glycogen and glucose transporter GLUT4 are decreased. [Ca2+]cytosol, increased to MHS levels, promoted GP phosphorylation. Imaging at ~100 nm resolution located GPa at sarcoplasmic reticulum (SR) junctional cisternae, and apo-GP at Z disk. MHS muscle therefore has a wide-ranging alteration in glucose metabolism: high [Ca2+]cytosol activates PhK, which inhibits GS, activates GP and moves it toward the SR, favoring glycogenolysis. The alterations probably cause these patients' hyperglycemia. For basic studies, MHS emerges as a variable stressor, which forces glucose pathways from the normal to the diseased range, thereby exposing novel metabolic links.
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Affiliation(s)
- Eshwar R Tammineni
- Department of Physiology and Biophysics, Rush University Medical CenterChicagoUnited States
| | - Natalia Kraeva
- Malignant Hyperthermia Investigation Unit (MHIU) of the University Health Network (Canada)TorontoCanada
- Department of Anaesthesia & Pain Management, Toronto General Hospital, UHN, University of TorontoTorontoCanada
| | - Lourdes Figueroa
- Department of Physiology and Biophysics, Rush University Medical CenterChicagoUnited States
| | - Carlo Manno
- Department of Physiology and Biophysics, Rush University Medical CenterChicagoUnited States
| | - Carlos A Ibarra
- Malignant Hyperthermia Investigation Unit (MHIU) of the University Health Network (Canada)TorontoCanada
- Department of Anaesthesia & Pain Management, Toronto General Hospital, UHN, University of TorontoTorontoCanada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick ChildrenTorontoCanada
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit (MHIU) of the University Health Network (Canada)TorontoCanada
- Department of Anaesthesia & Pain Management, Toronto General Hospital, UHN, University of TorontoTorontoCanada
| | - Eduardo Rios
- Department of Physiology and Biophysics, Rush University Medical CenterChicagoUnited States
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14
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Schiemann AH, Roesl C, Pollock N, Langton E, Bulger T, Stowell KM. Identification and Functional Analysis of RYR1 Variants in a Family with a Suspected Myopathy and Associated Malignant Hyperthermia. J Neuromuscul Dis 2020; 7:51-60. [PMID: 31903994 DOI: 10.3233/jnd-190430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The ryanodine receptor 1 (RyR1) is a major skeletal muscle calcium release channel located in the sarcoplasmic reticulum and involved in excitation-contraction coupling. Variants in the gene encoding RyR1 have been linked to a range of neuromuscular disorders including myopathies and malignant hyperthermia (MH). OBJECTIVE We have identified three RYR1 variants (c.1983 G>A, p.Trp661*; c.7025A>G, p.Asn2342Ser and c.2447 C>T, p.Pro816Leu) in a family with a suspected myopathy and associated malignant hyperthermia susceptibility. We used calcium release assays to functionally characterise these variants in a recombinant system. METHODS Site-directed mutagenesis was used to introduce each variant separately into the human RYR1 cDNA. HEK293-T cells were transfected with the recombinant constructs and calcium release assays were carried out using 4-chloro-m-cresol (4-CmC) as the RyR1 agonist to investigate the functional consequences of each variant. RESULTS RYR1 c.1983 G>A, p.Trp661* resulted in a non-functional channel, c.7025A>G, p.Asn2342Ser in a hypersensitive channel and c.2447 C>T, p.Pro816Leu in a hypersensitive channel at higher concentrations of 4-CmC. CONCLUSIONS The p.Trp661* RYR1 variant should be considered as a risk factor for myopathies. The p.Asn2342Ser RYR1 variant, when expressed as a compound heterozygote with a nonsense mutation on the second allele, is likely to result in MH-susceptibility. The role of the p.Pro816Leu variant in MH remains unclear.
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Affiliation(s)
- Anja H Schiemann
- School of Fundamental Sciences, Massey University, Manawatu, New Zealand
| | - Cornelia Roesl
- School of Fundamental Sciences, Massey University, Manawatu, New Zealand.,Present address: LifeArc, Nine, Edinburgh BioQuarter, Edinburgh, United Kingdom
| | - Neil Pollock
- Department of Anaesthesia and Intensive Care, Palmerston North Hospital, Manawatu, New Zealand.,Now retired
| | | | - Terasa Bulger
- Department of Anaesthesia and Intensive Care, Palmerston North Hospital, Manawatu, New Zealand
| | - Kathryn M Stowell
- School of Fundamental Sciences, Massey University, Manawatu, New Zealand
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15
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Chang L, Daly C, Miller DM, Allen PD, Boyle JP, Hopkins PM, Shaw MA. Permeabilised skeletal muscle reveals mitochondrial deficiency in malignant hyperthermia-susceptible individuals. Br J Anaesth 2019; 122:613-621. [PMID: 30916033 DOI: 10.1016/j.bja.2019.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/26/2019] [Accepted: 02/04/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Individuals genetically susceptible to malignant hyperthermia (MH) exhibit hypermetabolic reactions when exposed to volatile anaesthetics. Mitochondrial dysfunction has previously been associated with the MH-susceptible (MHS) phenotype in animal models, but evidence of this in human MH is limited. METHODS We used high resolution respirometry to compare oxygen consumption rates (oxygen flux) between permeabilised human MHS and MH-negative (MHN) skeletal muscle fibres with or without prior exposure to halothane. A substrate-uncoupler-inhibitor titration protocol was used to measure the following components of the electron transport chain under conditions of oxidative phosphorylation (OXPHOS) or after uncoupling the electron transport system (ETS): complex I (CI), complex II (CII), CI+CII and, as a measure of mitochondrial mass, complex IV (CIV). RESULTS Baseline comparisons without halothane exposure showed significantly increased mitochondrial mass (CIV, P=0.021) but lower flux control ratios in CI+CII(OXPHOS) and CII(ETS) of MHS mitochondria compared with MHN (P=0.033 and 0.005, respectively) showing that human MHS mitochondria have a functional deficiency. Exposure to halothane triggered a hypermetabolic response in MHS mitochondria, significantly increasing mass-specific oxygen flux in CI(OXPHOS), CI+CII(OXPHOS), CI+CII(ETS), and CII(ETS) (P=0.001-0.012), while the rates in MHN samples were unaltered by halothane exposure. CONCLUSIONS We present evidence of mitochondrial dysfunction in human MHS skeletal muscle both at baseline and after halothane exposure.
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Affiliation(s)
- Leon Chang
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - Catherine Daly
- Malignant Hyperthermia Unit, St James's University Hospital, Leeds, UK
| | - Dorota M Miller
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - Paul D Allen
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
| | - John P Boyle
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Philip M Hopkins
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK; Malignant Hyperthermia Unit, St James's University Hospital, Leeds, UK.
| | - Marie-Anne Shaw
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, UK
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16
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Dirksen R, Allen P, Lopez J. Understanding malignant hyperthermia: each move forward opens our eyes to the distance left to travel. Br J Anaesth 2019; 122:8-9. [DOI: 10.1016/j.bja.2018.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/12/2018] [Indexed: 10/27/2022] Open
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