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Cherchi C, Chiappini E, Amaddeo A, Chiarini Testa MB, Banfi P, Veneselli E, Cutrera R. Management of respiratory issues in patients with Rett syndrome: Italian experts' consensus using a Delphi approach. Pediatr Pulmonol 2024; 59:1970-1978. [PMID: 38721909 DOI: 10.1002/ppul.27030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/15/2024] [Accepted: 04/14/2024] [Indexed: 07/21/2024]
Abstract
BACKGROUND Despite the publication of the 2020 guidelines on how to manage Rett Syndrome (RS), some fundamental topics are still open, in particular respiratory problems. OBJECTIVE Identification and reinforcement of current recommendations concerning the management of respiratory issues in RS patients. MATERIALS AND METHODS Using a Delphi approach, the leading group reviewed the literature and formulated 14 statements. A multidisciplinary panel of 29 experts were invited to score, for each statement, their agreement on a 1-5 scale. The cut-off level for consensus was 75%, obtained through multiple rounds. RESULTS The panel agreed that in all RS types, respiratory issues should be faced at an early stage, regardless of epilepsy onset. It is recommended to perform periodically sleep studies in all Congenital Rett Syndrome, and in selected cases with other RS types. Noninvasive ventilation should be considered in all RS subjects with sleep respiratory disorders and in those with hypotonia associated with hypercapnia. Chest physiotherapy should be performed in all RS patients with difficult management of the accumulation of respiratory secretions, using airway clearance techniques and devices (PEP-mask, AMBU bag, or cough machine), more appropriate and tolerated by the patients. The panel recommended individualized programs for the management of scoliosis, and to consider performing gastrostomy in patients at increased risk of ab ingestis pneumonia. CONCLUSIONS This consensus could support everyday clinical practice on respiratory issues in RS patients, complementary to existing recommendations by regulatory agencies and guidelines.
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Affiliation(s)
- Claudio Cherchi
- Pediatric Pulmonology and Cystic Fibrosis Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Elena Chiappini
- Meyer Children's University Hospital, IRCCS, Florence, Italy
- Division of Pediatric Infectious Diseases Infective Diseases, Anna Meyer Children's University Hospital, Florence, Italy
| | - Alessandro Amaddeo
- Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy
| | | | - Paolo Banfi
- Heart-Respiratory Rehabilitation Unit, IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Edvige Veneselli
- Child Neuropsychiatry, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, DINOG-MI, University of Genoa, Genoa, Italy
| | - Renato Cutrera
- Pediatric Pulmonology and Cystic Fibrosis Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
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Cherchi C, Chiappini E, Chiarini Testa MB, Banfi P, Veneselli E, Cutrera R. Care Issues in Patients with Rett Syndrome: A Parental Perspective. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1713. [PMID: 37892376 PMCID: PMC10605630 DOI: 10.3390/children10101713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/12/2023] [Accepted: 10/17/2023] [Indexed: 10/29/2023]
Abstract
BACKGROUND The purpose of this study is to better understand the way caregivers of patients with Rett syndrome perceive the quality of the health care services they receive and identify its main shortcomings. METHODS A survey was distributed to all caregivers who are part of AIRETT (the Italian Association of Relatives of Patients with RS). The survey gathered information on the management of relatives of patients with Rett syndrome. RESULTS The data refers to 52 patients, all females, with a median age of 15 years at the time of the survey. Concerning RS specificity, our data confirm the high complexity of this chronic, multifaceted condition, mainly characterized by the presence of epilepsy, apnea, severe scoliosis, and gastrointestinal symptoms. The specialists more frequently involved in the care of patients were general practitioners or family pediatricians (98%) and neurologists (92%), and more rarely physiatrists (71%). Only 15% of patients were followed by a pulmonologist, despite the fact that respiratory problems were frequent (apneas were present in 81% of patients, and 2% had a tracheostomy). Although 63.5% of patients presented with gastrointestinal symptoms and 2% had a gastrostomy, only 33% were followed by a gastroenterologist. Moreover, although orthopedic issues were present in 78.8% of patients, including severe scoliosis in 22% of them, only 25% were followed by an orthopedist. Furthermore, despite the fact that RS patients are fragile, about one quarter of them were not vaccinated. As far as organizational issues are concerned, several specialized centers are located in various regions throughout the country. As a consequence, the high mobility rate from one center to another resulted in non-homogeneous assistance. CONCLUSIONS The study shows that caregivers of RS patients take over most obligations and burdens by increasing their perceived level of stress. For the majority of patients, the most frequent complications were not followed by the reference subspecialist, with the only exception of epilepsy. Moreover, improving vaccination strategies for these patients is necessary.
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Affiliation(s)
- Claudio Cherchi
- Pediatric Pulmonology and Cystic Fibrosis Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (M.B.C.T.); (R.C.)
| | - Elena Chiappini
- Department of Health Science, University of Florence, 50121 Florence, Italy;
- Division of Pediatric Infectious Diseases Infective Diseases, Anna Meyer Children’s University Hospital, 50100 Florence, Italy
| | - Maria Beatrice Chiarini Testa
- Pediatric Pulmonology and Cystic Fibrosis Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (M.B.C.T.); (R.C.)
| | - Paolo Banfi
- Heart-Respiratory Rehabilitation Unit, IRCCS Fondazione Don Carlo Gnocchi, 20148 Milan, Italy;
| | - Edvige Veneselli
- Child Neuropsychiatry, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, DINOG-MI, University of Genoa, 16100 Genoa, Italy;
| | - Renato Cutrera
- Pediatric Pulmonology and Cystic Fibrosis Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (M.B.C.T.); (R.C.)
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Leoncini S, Signorini C, Boasiako L, Scandurra V, Hayek J, Ciccoli L, Rossi M, Canitano R, De Felice C. Breathing Abnormalities During Sleep and Wakefulness in Rett Syndrome: Clinical Relevance and Paradoxical Relationship With Circulating Pro-oxidant Markers. Front Neurol 2022; 13:833239. [PMID: 35422749 PMCID: PMC9001904 DOI: 10.3389/fneur.2022.833239] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/02/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundBreathing abnormalities are common in Rett syndrome (RTT), a pervasive neurodevelopmental disorder almost exclusively affecting females. RTT is linked to mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Our aim was to assess the clinical relevance of apneas during sleep-wakefulness cycle in a population with RTT and the possible impact of apneas on circulating oxidative stress markers.MethodsFemale patients with a clinical diagnosis of typical RTT (n = 66), MECP2 gene mutation, and apneas were enrolled (mean age: 12.5 years). Baseline clinical severity, arterial blood gas analysis, and red blood cell count were assessed. Breathing was monitored during the wakefulness and sleep states (average recording time: 13 ± 0.5 h) with a portable polygraphic screening device. According to prevalence of breath holdings, the population was categorized into the wakefulness apnea (WA) and sleep apnea (SA) groups, and apnea-hypopnea index (AHI) was calculated. The impact of respiratory events on oxidative stress was assessed by plasma and intra-erythrocyte non-protein-bound iron (P-NPBI and IE-NPBI, respectively), and plasma F2-isoprostane (F2-IsoP) assays.ResultsSignificant prevalence of obstructive apneas with values of AHI > 15 was present in 69.7% of the population with RTT. The group with SA showed significantly increased AHI values > 15 (p = 0.0032), total breath holding episodes (p = 0.007), and average SpO2 (p = 0.0001) as well as lower nadir SpO2 (p = 0.0004) compared with the patients with WAs. The subgroups of patients with WA and SA showed no significant differences in arterial blood gas analysis variables (p > 0.089). Decreased mean cell hemoglobin (MCH) (p = 0.038) was observed in the group with WAs. P-NPBI levels were significantly higher in the group with WA than in that with SAs (p = 0.0001). Stepwise multiple linear regression models showed WA being related to nadir SpO2, average SpO2, and P-NPBI (adjusted R2 = 0.613, multiple correlation coefficient = 0.795 p < 0.0001), and P-NPBI being related to average SpO2, blood PaCO2, red blood cell mean corpuscular volume (MCV), age, and topiramate treatment (adjusted R2 = 0.551, multiple correlation coefficient = 0.765, p < 0.0001).ConclusionOur findings indicate that the impact of apneas in RTT is uneven according to the sleep-wakefulness cycle, and that plasma redox active iron represents a potential novel therapeutic target.
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Affiliation(s)
- Silvia Leoncini
- Rett Syndrome Trial Center, Child Neuropsychiatry Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Cinzia Signorini
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Lidia Boasiako
- Rett Syndrome Trial Center, Child Neuropsychiatry Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Valeria Scandurra
- Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Joussef Hayek
- Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Lucia Ciccoli
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Marcello Rossi
- Respiratory Pathophysiology and Rehabilitation Unit, University Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Roberto Canitano
- Child Neuropsychiatry Unit, University Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Claudio De Felice
- Rett Syndrome Trial Center, Child Neuropsychiatry Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Hinz L, Torrella Barrufet J, Heine VM. KCC2 expression levels are reduced in post mortem brain tissue of Rett syndrome patients. Acta Neuropathol Commun 2019; 7:196. [PMID: 31796123 PMCID: PMC6892240 DOI: 10.1186/s40478-019-0852-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/21/2019] [Indexed: 02/07/2023] Open
Abstract
Rett Syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the Methyl CpG binding protein 2 (MECP2) gene. Deficient K+-Cl-co-transporter 2 (KCC2) expression is suggested to play a key role in the neurodevelopmental delay in RTT patients' neuronal networks. KCC2 is a major player in neuronal maturation by supporting the GABAergic switch, through the regulation of neuronal chlorine homeostasis. Previous studies suggest that MeCP2 mutations lead to changed KCC2 expression levels, thereby causing a disturbance in excitation/inhibition (E/I) balance. To investigate this, we performed protein and RNA expression analysis on post mortem brain tissue from RTT patients and healthy controls. We showed that KCC2 expression, in particular the KCC2a isoform, is relatively decreased in RTT patients. The expression of Na+-K+-Cl- co-transporter 1 (NKCC1), responsible for the inward transport of chlorine, is not affected, leading to a reduced KCC2/NKCC1 ratio in RTT brains. Our report confirms KCC2 expression alterations in RTT patients in human brain tissue, which is in line with other studies, suggesting affected E/I balance could underlie neurodevelopmental defects in RTT patients.
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Affiliation(s)
- Lisa Hinz
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, The Netherlands
| | - Joan Torrella Barrufet
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, The Netherlands
| | - Vivi M Heine
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, The Netherlands.
- Pediatric Neurology, Emma Children's Hospital, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Boelelaan 1085, 1081HV, Amsterdam, The Netherlands.
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Sarber KM, Howard JJM, Dye TJ, Pascoe JE, Simakajornboon N. Sleep-Disordered Breathing in Pediatric Patients With Rett Syndrome. J Clin Sleep Med 2019; 15:1451-1457. [PMID: 31596210 PMCID: PMC6778339 DOI: 10.5664/jcsm.7974] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 11/13/2022]
Abstract
STUDY OBJECTIVES Although respiratory abnormalities occurring during wakefulness are well recognized in patients with Rett syndrome (RS), less has been reported regarding sleep-disordered breathing (SDB) in this population. This study aims to characterize the presenting complaints, types and severity of SDB, and treatment modalities of patients with RS and sleep concerns. METHODS Retrospective chart review of pediatric patients with RS referred to our academic tertiary care institution from January 2007 to July 2017. RESULTS Thirteen patients were identified, 11 female (84.6%); mean age at polysomnography (PSG) was 10.3 years (standard deviation 4.94). Eleven were white (84.6%), 2 were black (15.4%). The most common presenting symptoms were snoring (10/13, 77%) and witnessed apnea (7/13, 53.8%). On baseline PSG, all patients (100%) exhibited hyperapneas followed by a central apnea during wake. Nine (69.2%) had obstructive sleep apnea (OSA) (obstructive apnea-hypopnea index (oAHI) > 1); four had severe OSA (oAHI ≥ 10). One had central sleep apnea (central apnea index > 5) and severe OSA. No patients exhibited hypoventilation on baseline PSG. Mean AHI of all patients was 8.77 ± 8.82 (oAHI 6.51 ± 6.91) events/h. Mean oxyhemoglobin nadir was 88.52 ± 5.6%. Treatment modalities included observation: 5 (38%), acetazolamide: 2 (15%), nasal mometasone: 1 (7.7%), adenotonsillectomy: 3 (23.1%), and positive airway pressure: 2 (15%). CONCLUSIONS Regarding patients with RS referred to the sleep medicine clinic, snoring and witnessed apneas were the most common presenting complaints. In addition to breathing abnormalities during wake, OSA was very common in our cohort. Further studies are needed to examine the pathogenesis of OSA in RS and relationships between disease genotype and respiratory abnormality phenotype.
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Affiliation(s)
- Kathleen M. Sarber
- Cincinnati Children’s Hospital Medical Center, Division of Pulmonary and Sleep Medicine, Cincinnati, Ohio
| | | | - Thomas J. Dye
- Cincinnati Children’s Hospital Medical Center, Division of Pulmonary and Sleep Medicine, Cincinnati, Ohio
- Cincinnati Children’s Hospital Medical Center, Division of Neurology, Cincinnati, Ohio
- University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, Ohio
| | - John E. Pascoe
- Cincinnati Children’s Hospital Medical Center, Division of Pulmonary and Sleep Medicine, Cincinnati, Ohio
- University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, Ohio
| | - Narong Simakajornboon
- Cincinnati Children’s Hospital Medical Center, Division of Pulmonary and Sleep Medicine, Cincinnati, Ohio
- University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, Ohio
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Wittman S, Abdala AP, Rubin JE. Reduced computational modelling of Kölliker-Fuse contributions to breathing patterns in Rett syndrome. J Physiol 2019; 597:2651-2672. [PMID: 30908648 DOI: 10.1113/jp277592] [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: 12/19/2018] [Accepted: 03/07/2019] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Reduced computational models are used to test effects of loss of inhibition to the Kölliker-Fuse nucleus (KFn). Three reduced computational models that simulate eupnoeic and vagotomized respiratory rhythms are considered. All models exhibit the emergence of respiratory perturbations associated with Rett syndrome as inhibition to the KFn is diminished. Simulations suggest that application of 5-HT1A agonists can mitigate the respiratory pathology. The three models can be distinguished and tested based on their predictions about connections and dynamics within the respiratory circuit and about effects of perturbations on certain respiratory neuron populations. ABSTRACT Rett syndrome (RTT) is a developmental disorder that can lead to respiratory disturbances featuring prolonged apnoeas of variable durations. Determining the mechanisms underlying these effects at the level of respiratory neural circuits would have significant implications for treatment efforts and would also enhance our understanding of respiratory rhythm generation and control. While experimental studies have suggested possible factors contributing to the respiratory patterns of RTT, we take a novel computational approach to the investigation of RTT, which allows for direct manipulation of selected system parameters and testing of specific hypotheses. Specifically, we present three reduced computational models, developed using an established framework, all of which successfully simulate respiratory outputs across eupnoeic and vagotomized conditions. All three models show that loss of inhibition to the Kölliker-Fuse nucleus reproduces the key respiratory alterations associated with RTT and, as suggested experimentally, that effects of 5-HT1A agonists on the respiratory neural circuit suffice to alleviate this respiratory pathology. Each of the models makes distinct predictions regarding the neuronal populations and interactions underlying these effects, suggesting natural directions for future experimental testing.
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Affiliation(s)
- Samuel Wittman
- Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, PA, 15260, USA
| | - Ana Paula Abdala
- School of Physiology, Pharmacology & Neuroscience, Faculty of Life Sciences, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Jonathan E Rubin
- Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, PA, 15260, USA.,Center for the Neural Basis of Cognition, University of Pittsburgh, 4400 Fifth Avenue, Pittsburgh, PA, 15213, USA
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Marina N, Turovsky E, Christie IN, Hosford PS, Hadjihambi A, Korsak A, Ang R, Mastitskaya S, Sheikhbahaei S, Theparambil SM, Gourine AV. Brain metabolic sensing and metabolic signaling at the level of an astrocyte. Glia 2018; 66:1185-1199. [PMID: 29274121 PMCID: PMC5947829 DOI: 10.1002/glia.23283] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/04/2017] [Accepted: 11/29/2017] [Indexed: 12/18/2022]
Abstract
Astrocytes support neuronal function by providing essential structural and nutritional support, neurotransmitter trafficking and recycling and may also contribute to brain information processing. In this article we review published results and report new data suggesting that astrocytes function as versatile metabolic sensors of central nervous system (CNS) milieu and play an important role in the maintenance of brain metabolic homeostasis. We discuss anatomical and functional features of astrocytes that allow them to detect and respond to changes in the brain parenchymal levels of metabolic substrates (oxygen and glucose), and metabolic waste products (carbon dioxide). We report data suggesting that astrocytes are also sensitive to circulating endocrine signals-hormones like ghrelin, glucagon-like peptide-1 and leptin, that have a major impact on the CNS mechanisms controlling food intake and energy balance. We discuss signaling mechanisms that mediate communication between astrocytes and neurons and consider how these mechanisms are recruited by astrocytes activated in response to various metabolic challenges. We review experimental data suggesting that astrocytes modulate the activities of the respiratory and autonomic neuronal networks that ensure adaptive changes in breathing and sympathetic drive in order to support the physiological and behavioral demands of the organism in ever-changing environmental conditions. Finally, we discuss evidence suggesting that altered astroglial function may contribute to the pathogenesis of disparate neurological, respiratory and cardiovascular disorders such as Rett syndrome and systemic arterial hypertension.
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Affiliation(s)
- Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
- Research Department of Metabolism and Experimental Therapeutics, Division of MedicineUniversity College LondonLondonWC1E 6JJUnited Kingdom
| | - Egor Turovsky
- Laboratory of Intracellular SignallingInstitute of Cell Biophysics, Russian Academy of SciencesPushchinoRussia
| | - Isabel N Christie
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Patrick S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Anna Hadjihambi
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Richard Ang
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Svetlana Mastitskaya
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Shahriar Sheikhbahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Shefeeq M Theparambil
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology & PharmacologyUniversity College LondonLondonWC1E 6BTUnited Kingdom
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Balakrishnan S, Mironov SL. Rescue of hyperexcitability in hippocampal CA1 neurons from Mecp2 (-/y) mouse through surface potential neutralization. PLoS One 2018; 13:e0195094. [PMID: 29621262 PMCID: PMC5886422 DOI: 10.1371/journal.pone.0195094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/18/2018] [Indexed: 11/19/2022] Open
Abstract
Hyperventilation is a known feature of Rett syndrome (RTT). However, how hyperventilation is related to other RTT symptoms such as hyperexcitability is unknown. Intense breathing during hyperventilation induces hypocapnia and culminates in respiratory alkalosis. Alkalinization of extracellular milieu can trigger epilepsy in patients who already have neuronal hyperexcitability. By combining patch-clamp electrophysiology and quantitative glutamate imaging, we compared excitability of CA1 neurons of WT and Mecp2 (-/y) mice, and analyzed the biophysical properties of subthreshold membrane channels. The results show that Mecp2 (-/y) CA1 neurons are hyperexcitable in normal pH (7.4) and are increasingly vulnerable to alkaline extracellular pH (8.4), during which their excitability increased further. Under normal pH conditions, an abnormal negative shift in the voltage-dependencies of HCN (hyperpolarization-activated cyclic nucleotide-gated) and calcium channels in the CA1 neurons of Mecp2 (-/y) mice was observed. Alkaline pH also enhanced excitability in wild-type (WT) CA1 neurons through modulation of the voltage dependencies of HCN- and calcium channels. Additionally alkaline pH augmented spontaneous glutamate release and burst firing in WT CA1 neurons. Conversely, acidic pH (6.4) and 8 mM Mg2+ exerted the opposite effect, and diminished hyperexcitability in Mecp2 (-/y) CA1 neurons. We propose that the observed effects of pH and Mg2+ are mediated by changes in the neuronal membrane surface potential, which consecutively modulates the gating of HCN and calcium channels. The results provide insight to pivotal cellular mechanisms that can regulate neuronal excitability and help to devise treatment strategies for hyperexcitability induced symptoms of Rett syndrome.
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Affiliation(s)
- Saju Balakrishnan
- CNMPB (Centre for Nanoscale Microscopy and Molecular Physiology of the Brain, Cluster of Excellence 171, DFG Research Center 103), Institute of Neuro and Sensory Physiology, Georg-August-University, Göttingen, Germany
| | - Sergej L. Mironov
- CNMPB (Centre for Nanoscale Microscopy and Molecular Physiology of the Brain, Cluster of Excellence 171, DFG Research Center 103), Institute of Neuro and Sensory Physiology, Georg-August-University, Göttingen, Germany
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Mackay J, Downs J, Wong K, Heyworth J, Epstein A, Leonard H. Autonomic breathing abnormalities in Rett syndrome: caregiver perspectives in an international database study. J Neurodev Disord 2017; 9:15. [PMID: 28465761 PMCID: PMC5410057 DOI: 10.1186/s11689-017-9196-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 04/21/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Rett syndrome is a severe neurodevelopmental disorder associated with mutations in the MECP2 gene. Irregular breathing patterns and abdominal bloating are prominent but poorly understood features. Our aims were to characterize the abnormal breathing patterns and abdominal bloating, investigate the distribution of these by age and mutation type and examine their impact and management from a caregiver perspective. METHODS We invited previously recruited families from the International Rett Syndrome Study to complete a web-based questionnaire concerning their family member with Rett syndrome aged between 2 and 57 years. We used logistic regression to investigate presence, frequency and impact of breath-holding, hyperventilation, or abdominal bloating by age group and mutation type. Age of onset for both breathing abnormalities was investigated using time-to-onset analysis, and the Kaplan-Meier method was used to estimate the failure function for the study sample. Descriptive statistics were used to characterize the management of irregular breathing. RESULTS Questionnaires were returned by 413/482 (85.7%) families. Breath-holding was reported for 68.8%, hyperventilation for 46.4% and abdominal bloating for 42.4%. Hyperventilation was more prevalent and frequent in those younger than 7 years of age and abdominal bloating in those aged over 20 years. Onset of breathing irregularities usually occurred during early childhood. Caregivers perceived that daily life was considerably impacted for almost half (44.1%) of those with abdominal bloating and in just over than a third of those with breath-holding (35.8%) or hyperventilation (35.1%). Although perceived impact was broadly comparable between age and mutation groups for breath-holding, hyperventilation and abdominal bloating, girls and women with a p.Arg294* mutation were considered to be more affected by all three conditions. Only 31 individuals had received medically prescribed treatments including 12 different medications, added oxygen, rebreathing apparatus or non-invasive ventilation. CONCLUSIONS Autonomic disturbances are prevalent and burdensome in Rett syndrome. This information may guide the design of inclusion criteria and outcome measures for clinical intervention trials targeting autonomic abnormalities. Further investigation of available treatments is necessary to delineate evidence-based management pathways.
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Affiliation(s)
- Jessica Mackay
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
- School of Population Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Jenny Downs
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
- School of Physiotherapy and Exercise Science, Curtin University, GPO Box U1987, Perth, WA 6845 Australia
| | - Kingsley Wong
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
| | - Jane Heyworth
- School of Population Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Amy Epstein
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
| | - Helen Leonard
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
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Ming X, Patel R, Kang V, Chokroverty S, Julu PO. Respiratory and autonomic dysfunction in children with autism spectrum disorders. Brain Dev 2016; 38:225-32. [PMID: 26235973 DOI: 10.1016/j.braindev.2015.07.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/02/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Cardiac parasympathetic hypofunction has been reported in autism spectrum disorders (ASD). This usually is linked to respiratory dysrhythmia which has been documented in some children with ASD. OBJECTIVES This study evaluated the cardiorespiratory functions in ASD to elucidate the physiologic basis of behaviors. METHODS Nineteen children with ASD and 18 age matched controls underwent autonomic function monitoring at a defined resting state using the NeuroScope. The non-invasive real time beat-to-beat blood pressure was measured by Portapres and fed into the NeuroScope where heart rate, cardiac vagal tone and cardiac sensitivity to baroreceptor were derived from the EKG and blood pressure waveforms using the Vagosoft software; and respiratory rate and rhythm were measured simultaneously by plethysmograph. Respiration was analyzed breath by breath using our prior published methods. RESULTS Various respiratory dysrhythmias, particularly Biot's and Cheyne-Stokes respiration, were detected in children with ASD, who also exhibited greater variability in respiratory rhythm and amplitudes than controls. The respiratory dysrhythmia in children with ASD was associated with a lower cardiac vagal activity. CONCLUSION The Biot's breathing and Cheyne-Stokes respiration coupled with cardiac vagal hypofunction in ASD suggest a brainstem dysfunction consistent with our previous findings. The low parasympathetic activity could explain in part the chronic sensory hyperarousal state in children with ASD.
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Affiliation(s)
- Xue Ming
- Department of Neurosciences and Neurology, New Jersey Medical School, Rutgers University, USA; New Jersey Neuroscience Institute, Sleep Medicine Center, JFK Medical Center, Seton Hall University, USA.
| | | | - Victor Kang
- School of Arts and Sciences, Johns Hopkins University, USA
| | - Sudhansu Chokroverty
- New Jersey Neuroscience Institute, Sleep Medicine Center, JFK Medical Center, Seton Hall University, USA
| | - Peter O Julu
- Division of Brain Sciences, Department of Medicine, Imperial College, UK; Swedish National Rett Center, Sweden; Department of Neuroscience, Breakspear Medical Group, UK
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11
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Turovsky E, Karagiannis A, Abdala AP, Gourine AV. Impaired CO2 sensitivity of astrocytes in a mouse model of Rett syndrome. J Physiol 2015; 593:3159-68. [PMID: 25981852 PMCID: PMC4532534 DOI: 10.1113/jp270369] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/11/2015] [Indexed: 12/13/2022] Open
Abstract
Rett syndrome, a prototypical neurological disorder caused by loss of function of the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2) gene, is associated with a severely disordered breathing pattern and reduced ventilatory CO2 sensitivity. In a mouse model of Rett syndrome (MeCP2 knockout), re-introduction of the MeCP2 gene selectively in astrocytes rescues normal respiratory phenotype. In the present study we determined whether the metabolic and/or signalling functions of astrocytes are affected by testing the hypotheses that in conditions of MeCP2 deficiency, medullary astrocytes are unable to produce/release appropriate amounts of lactate or detect changes in PCO2/[H(+) ], or both. No differences in tonic or hypoxia-induced release of lactate from the ventral surface of the medulla oblongata or cerebral cortex in brain slices of MeCP2-knockout and wild-type mice were found. In brainstem slices of wild-type mice, respiratory acidosis triggered robust elevations in [Ca(2+) ]i in astrocytes residing near the ventral surface of the medulla oblongata. The magnitude of CO2 -induced [Ca(2+) ]i responses in medullary astrocytes was markedly reduced in conditions of MeCP2 deficiency, whereas [Ca(2+) ]i responses to ATP were unaffected. These data suggest that (i) metabolic function of astrocytes in releasing lactate into the extracellular space is not affected by MeCP2 deficiency, and (ii) MeCP2 deficiency impairs the ability of medullary astrocytes to sense changes in PCO2/[H(+) ]. Taken together with the evidence of severely blunted ventilatory sensitivity to CO2 in mice with conditional MeCP2 deletion in astroglia, these data support the hypothesis of an important role played by astrocytes in central respiratory CO2 /pH chemosensitivity.
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Affiliation(s)
- Egor Turovsky
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.,Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Anastassios Karagiannis
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ana Paula Abdala
- School of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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12
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Abdala AP, Lioy DT, Garg SK, Knopp SJ, Paton JFR, Bissonnette JM. Effect of Sarizotan, a 5-HT1a and D2-like receptor agonist, on respiration in three mouse models of Rett syndrome. Am J Respir Cell Mol Biol 2014; 50:1031-9. [PMID: 24351104 PMCID: PMC4068914 DOI: 10.1165/rcmb.2013-0372oc] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/10/2013] [Indexed: 01/06/2023] Open
Abstract
Disturbances in respiration are common and debilitating features of Rett syndrome (RTT). A previous study showed that the 5-HT1a receptor agonist (R)-(+)-8-hydroxy-dipropyl-2-aminotetralin hydrobromide (8-OH-DPAT) significantly reduced the incidence of apnea and the irregular breathing pattern in a mouse model of the disorder. 8-OH-DPAT, however, is not available for clinical practice. Sarizotan, a full 5-HT1a agonist and a dopamine D2-like agonist/partial agonist, has been used in clinical trials for the treatment of l-dopa-induced dyskinesia. The purpose of this study was to evaluate the effects of sarizotan on respiration and locomotion in mouse models of RTT. Studies were performed in Bird and Jaenisch strains of methyl-CpG-binding protein 2--deficient heterozygous female and Jaenisch strain Mecp2 null male mice and in knock-in heterozygous female mice of a common nonsense mutation (R168X). Respiratory pattern was determined with body plethysmography, and locomotion was determined with open-field recording. Sarizotan or vehicle was administered 20 minutes before a 30-minute recording of respiratory pattern or motor behavior. In separate studies, a crossover design was used to administer the drug for 7 and for 14 days. Sarizotan reduced the incidence of apnea in all three RTT mouse models to approximately 15% of their pretreatment levels. The irregular breathing pattern was corrected to that of wild-type littermates. When administered for 7 or 14 days, apnea decreased to 25 to 33% of the incidence seen with vehicle. This study indicates that the clinically approved drug sarizotan is an effective treatment for respiratory disorders in mouse models of RTT.
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Affiliation(s)
- Ana P. Abdala
- Department of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, United Kingdom; and
| | | | | | | | - Julian F. R. Paton
- Department of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, United Kingdom; and
| | - John M. Bissonnette
- Departments of Obstetrics & Gynecology, and
- Cell & Developmental Biology, Oregon Health and Science University, Portland, Oregon
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13
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Abdala AP, Bissonnette JM, Newman-Tancredi A. Pinpointing brainstem mechanisms responsible for autonomic dysfunction in Rett syndrome: therapeutic perspectives for 5-HT1A agonists. Front Physiol 2014; 5:205. [PMID: 24910619 PMCID: PMC4038922 DOI: 10.3389/fphys.2014.00205] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 05/12/2014] [Indexed: 12/26/2022] Open
Abstract
Rett syndrome is a neurological disorder caused by loss of function of methyl-CpG-binding protein 2 (MeCP2). Reduced function of this ubiquitous transcriptional regulator has a devastating effect on the central nervous system. One of the most severe and life-threatening presentations of this syndrome is brainstem dysfunction, which results in autonomic disturbances such as breathing deficits, typified by episodes of breathing cessation intercalated with episodes of hyperventilation or irregular breathing. Defects in numerous neurotransmitter systems have been observed in Rett syndrome both in animal models and patients. Here we dedicate special attention to serotonin due to its role in promoting regular breathing, increasing vagal tone, regulating mood, alleviating Parkinsonian-like symptoms and potential for therapeutic translation. A promising new symptomatic strategy currently focuses on regulation of serotonergic function using highly selective serotonin type 1A (5-HT1A) “biased agonists.” We address this newly emerging therapy for respiratory brainstem dysfunction and challenges for translation with a holistic perspective of Rett syndrome, considering potential mood and motor effects.
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Affiliation(s)
- Ana P Abdala
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| | - John M Bissonnette
- Department of Obstetrics and Gynecology, Oregon Health and Science University Portland, OR, USA
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14
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Inflammatory lung disease in Rett syndrome. Mediators Inflamm 2014; 2014:560120. [PMID: 24757286 PMCID: PMC3976920 DOI: 10.1155/2014/560120] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/06/2014] [Accepted: 01/14/2014] [Indexed: 12/30/2022] Open
Abstract
Rett syndrome (RTT) is a pervasive neurodevelopmental disorder mainly linked to mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2). Respiratory dysfunction, historically credited to brainstem immaturity, represents a major challenge in RTT. Our aim was to characterize the relationships between pulmonary gas exchange abnormality (GEA), upper airway obstruction, and redox status in patients with typical RTT (n = 228) and to examine lung histology in a Mecp2-null mouse model of the disease. GEA was detectable in ~80% (184/228) of patients versus ~18% of healthy controls, with “high” (39.8%) and “low” (34.8%) patterns dominating over “mixed” (19.6%) and “simple mismatch” (5.9%) types. Increased plasma levels of non-protein-bound iron (NPBI), F2-isoprostanes (F2-IsoPs), intraerythrocyte NPBI (IE-NPBI), and reduced and oxidized glutathione (i.e., GSH and GSSG) were evidenced in RTT with consequently decreased GSH/GSSG ratios. Apnea frequency/severity was positively correlated with IE-NPBI, F2-IsoPs, and GSSG and negatively with GSH/GSSG ratio. A diffuse inflammatory infiltrate of the terminal bronchioles and alveoli was evidenced in half of the examined Mecp2-mutant mice, well fitting with the radiological findings previously observed in RTT patients. Our findings indicate that GEA is a key feature of RTT and that terminal bronchioles are a likely major target of the disease.
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15
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Bissonnette JM, Schaevitz LR, Knopp SJ, Zhou Z. Respiratory phenotypes are distinctly affected in mice with common Rett syndrome mutations MeCP2 T158A and R168X. Neuroscience 2014; 267:166-76. [PMID: 24626160 DOI: 10.1016/j.neuroscience.2014.02.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 12/16/2022]
Abstract
Respiratory disturbances are a primary phenotype of the neurological disorder, Rett syndrome (RTT), caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). Mouse models generated with null mutations in Mecp2 mimic respiratory abnormalities in RTT girls. Large deletions, however, are seen in only ∼10% of affected human individuals. Here we characterized respiration in heterozygous females from two mouse models that genetically mimic common RTT point mutations, a missense mutation T158A (Mecp2(T158A/)(+)) or a nonsense mutation R168X (Mecp2(R168X/+)). MeCP2 T158A shows decreased binding to methylated DNA, while MeCP2 R168X retains the capacity to bind methylated DNA but lacks the ability to recruit complexes required for transcriptional repression. We found that both Mecp2(T158A/+) and Mecp2(R168X/+) heterozygotes display augmented hypoxic ventilatory responses and depressed hypercapnic responses, compared to wild-type controls. Interestingly, the incidence of apnea was much greater in Mecp2(R168X/+) heterozygotes, 189 per hour, than Mecp2(T158A/+) heterozygotes, 41 per hour. These results demonstrate that different RTT mutations lead to distinct respiratory phenotypes, suggesting that characterization of the respiratory phenotype may reveal functional differences between MeCP2 mutations and provide insights into the pathophysiology of RTT.
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Affiliation(s)
- J M Bissonnette
- Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, OR, USA; Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR, USA.
| | - L R Schaevitz
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - S J Knopp
- Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Z Zhou
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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16
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When norepinephrine becomes a driver of breathing irregularities: how intermittent hypoxia fundamentally alters the modulatory response of the respiratory network. J Neurosci 2014; 34:36-50. [PMID: 24381266 DOI: 10.1523/jneurosci.3644-12.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Neuronal networks are endogenously modulated by aminergic and peptidergic substances. These modulatory processes are critical for maintaining normal activity and adapting networks to changes in metabolic, behavioral, and environmental conditions. However, disturbances in neuromodulation have also been associated with pathologies. Using whole animals (in vivo) and functional brainstem slices (in vitro) from mice, we demonstrate that exposure to acute intermittent hypoxia (AIH) leads to fundamental changes in the neuromodulatory response of the respiratory network located within the preBötzinger complex (preBötC), an area critical for breathing. Norepinephrine, which normally regularizes respiratory activity, renders respiratory activity irregular after AIH. Respiratory irregularities are caused both in vitro and in vivo by AIH, which increases synaptic inhibition within the preBötC when norepinephrine is endogenously or exogenously increased. These irregularities are prevented by blocking synaptic inhibition before AIH. However, regular breathing cannot be reestablished if synaptic inhibition is blocked after AIH. We conclude that subtle changes in synaptic transmission can have dramatic consequences at the network level as endogenously released neuromodulators that are normally adaptive become the drivers of irregularity. Moreover, irregularities in the preBötC result in irregularities in the motor output in vivo and in incomplete transmission of inspiratory activity to the hypoglossus motor nucleus. Our finding has basic science implications for understanding network functions in general, and it may be clinically relevant for understanding pathological disturbances associated with hypoxic episodes such as those associated with myocardial infarcts, obstructive sleep apneas, apneas of prematurity, Rett syndrome, and sudden infant death syndrome.
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17
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Gallego J. Genetic diseases: congenital central hypoventilation, Rett, and Prader-Willi syndromes. Compr Physiol 2013; 2:2255-79. [PMID: 23723037 DOI: 10.1002/cphy.c100037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The present review summarizes current knowledge on three rare genetic disorders of respiratory control, congenital central hypoventilation syndrome (CCHS), Rett syndrome (RTT), and Prader-Willi syndrome (PWS). CCHS is characterized by lack of ventilatory chemosensitivity caused by PHOX2B gene abnormalities consisting mainly of alanine expansions. RTT is associated with episodes of tachypneic and irregular breathing intermixed with breathholds and apneas and is caused by mutations in the X-linked MECP2 gene encoding methyl-CpG-binding protein. PWS manifests as sleep-disordered breathing with apneas and episodes of hypoventilation and is caused by the loss of a group of paternally inherited genes on chromosome 15. CCHS is the most specific disorder of respiratory control, whereas the breathing disorders in RTT and PWS are components of a more general developmental disorder. The main clinical features of these three disorders are reviewed with special emphasis on the associated brain abnormalities. In all three syndromes, disease-causing genetic defects have been identified, allowing the development of genetically engineered mouse models. New directions for future therapies based on these models or, in some cases, on clinical experience are delineated. Studies of CCHS, RTT, and PWS extend our knowledge of the molecular and cellular aspects of respiratory rhythm generation and suggest possible pharmacological approaches to respiratory control disorders. This knowledge is relevant for the clinical management of many respiratory disorders that are far more prevalent than the rare diseases discussed here.
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Affiliation(s)
- Jorge Gallego
- Inserm U676 and University of Paris Diderot, Paris, France.
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18
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Levitt ES, Hunnicutt BJ, Knopp SJ, Williams JT, Bissonnette JM. A selective 5-HT1a receptor agonist improves respiration in a mouse model of Rett syndrome. J Appl Physiol (1985) 2013; 115:1626-33. [PMID: 24092697 DOI: 10.1152/japplphysiol.00889.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rett syndrome is a neurological disorder caused by loss of function mutations in the gene that encodes the DNA binding protein methyl-CpG-binding protein 2 (Mecp2). A prominent feature of the syndrome is disturbances in respiration characterized by frequent apnea and an irregular interbreath cycle. 8-Hydroxy-2-dipropylaminotetralin has been shown to positively modulate these disturbances (Abdala AP, Dutschmann M, Bissonnette JM, Paton JF, Proc Natl Acad Sci U S A 107: 18208-18213, 2010), but the mode of action is not understood. Here we show that the selective 5-HT1a biased agonist 3-chloro-4-fluorophenyl-(4-fluoro-4-{[(5-methylpyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone (F15599) decreases apnea and corrects irregularity in both heterozygous Mecp2-deficient female and in Mecp2 null male mice. In whole cell voltage-clamp recordings from dorsal raphe neurons, F15599 potently induced an outward current, which was blocked by barium, reversed at the potassium equilibrium potential, and was antagonized by the 5-HT1a antagonist WAY100135. This is consistent with somatodendritic 5-HT1a receptor-mediated activation of G protein-coupled inwardly rectifying potassium channels (GIRK). In contrast, F15599 did not activate 5-HT1b/d receptors that mediate inhibition of glutamate release from terminals in the nucleus accumbens by a presynaptic mechanism. Thus F15599 activated somatodendritic 5-HT1a autoreceptors, but not axonal 5-HT1b/d receptors. In unanesthetized Mecp2-deficient heterozygous female mice, F15599 reduced apnea in a dose-dependent manner with maximal effect of 74.5 ± 6.9% at 0.1 mg/kg and improved breath irrregularity. Similarly, in Mecp2 null male mice, apnea was reduced by 62 ± 6.6% at 0.25 mg/kg, and breathing became regular. The results indicate respiration is improved with a 5-HT1a agonist that activates GIRK channels without affecting neurotransmitter release.
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Affiliation(s)
- Erica S Levitt
- Vollum Institute, Oregon Health and Science University, Portland, Oregon
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19
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Ramirez JM, Ward CS, Neul JL. Breathing challenges in Rett syndrome: lessons learned from humans and animal models. Respir Physiol Neurobiol 2013; 189:280-7. [PMID: 23816600 DOI: 10.1016/j.resp.2013.06.022] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 06/21/2013] [Accepted: 06/24/2013] [Indexed: 01/17/2023]
Abstract
Breathing disturbances are a major challenge in Rett Syndrome (RTT). These disturbances are more pronounced during wakefulness; but irregular breathing occurs also during sleep. During the day patients can exhibit alternating bouts of hypoventilation and irregular hyperventilation. But there is significant individual variability in severity, onset, duration and type of breathing disturbances. Research in mouse models of RTT suggests that different areas in the ventrolateral medulla and pons give rise to different aspects of this breathing disorder. Pre-clinical experiments in mouse models that target different neuromodulatory and neurotransmitter receptors and MeCP2 function within glia cells can partly reverse breathing abnormalities. The success in animal models raises optimism that one day it will be possible to control or potentially cure the devastating symptoms also in human patients with RTT.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Neurological Surgery, University of Washington, Seattle, WA 98101, USA.
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Hagebeuk EEO, van den Bossche RAS, de Weerd AW. Respiratory and sleep disorders in female children with atypical Rett syndrome caused by mutations in the CDKL5 gene. Dev Med Child Neurol 2013; 55:480-4. [PMID: 23151060 DOI: 10.1111/j.1469-8749.2012.04432.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM In female children with drug-resistant seizures and developmental delay from birth, atypical Rett syndrome caused by mutations in the CDKL5 gene should be considered. Several clinical features resemble classic Rett syndrome. Respiratory and sleep abnormalities are frequently present in Rett syndrome, whereas little is known in patients with CDKL5 mutations. METHOD In four genetically confirmed female patients with CDKL5 mutations (age range 2-15 y), the presence of breathing and sleep abnormalities was evaluated using the validated Sleep Disturbance Scale for Children and polysomnography (PSG). RESULTS The Sleep Disturbance Scale for Children indicated disorders of initiating and maintaining sleep, daytime somnolence, and sleep breathing disorders. In one patient, PSG showed central apnoeas during sleep: her total apnoea-hypopnoea index (AHI) was 4.9, of which the central AHI was 3.4/h. When awake, central apnoeas were present in two of the four female children (central AHI 28/h and 41/h respectively), all preceded by hyperventilation. PSG showed low rapid eye movement (REM) sleep (9.7-18.3%), frequent awakenings, and low sleep efficiency (range 59-78%). INTERPRETATION Episodic hyperventilation followed by central apnoeas was present while awake in two of four patients. This may indicate failure of brainstem respiratory centres. In addition, low REM sleep, frequent arousals (not caused by apnoeas/seizures), and low sleep efficiency were present. Similar to Rett syndrome, in patients with CDKL5 mutations PSG seems warranted to evaluate breathing and sleep disturbances.
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Affiliation(s)
- Eveline E O Hagebeuk
- Pediatric Department, Stichting Epilepsie Instellingen, Zwolle, The Netherlands.
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Maini I, Cantalupo G, Turco EC, De Paolis F, Magnani C, Parrino L, Terzano MG, Pisani F. Clinical and polygraphic improvement of breathing abnormalities after valproate in a case of Pitt-Hopkins syndrome. J Child Neurol 2012; 27:1585-8. [PMID: 22378662 DOI: 10.1177/0883073811435917] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Pitt-Hopkins syndrome is a rare genetic form of severe psychomotor delay, caused by mutations in transcription cell factor-4 gene and characterized by distinctive dysmorphic features and abnormal breathing pattern. The current report describes the polygraphic features of the syndrome's typical breathing pattern in a patient both in wakefulness and in sleep. The control of these breathing alterations is important to prevent the neurological sequelae linked to chronic cerebral hypoxemia in early ages. No data are available on effective treatment options for breathing abnormalities of Pitt-Hopkins syndrome. The authors polygraphically documented a reduction of apneic and hypopneic phenomena, with a significant improvement in saturation values, after the introduction of sodium valproate.
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Affiliation(s)
- Ilenia Maini
- Child Neuropsychiatry Unit, University of Parma, Parma, Italy
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Toward MA, Abdala AP, Knopp SJ, Paton JFR, Bissonnette JM. Increasing brain serotonin corrects CO2 chemosensitivity in methyl-CpG-binding protein 2 (Mecp2)-deficient mice. Exp Physiol 2012. [PMID: 23180809 DOI: 10.1113/expphysiol.2012.069872] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mice deficient in the transcription factor methyl-CpG-binding protein 2 (Mecp2), a mouse model of Rett syndrome, display reduced CO2 chemosensitivity, which may contribute to their breathing abnormalities. In addition, patients with Rett syndrome and male mice that are null for Mecp2 show reduced levels of brain serotonin (5-HT). Serotonin is known to play a role in central chemosensitivity, and we hypothesized that increasing the availability of 5-HT in this mouse model would improve their respiratory response to CO2. Here we determined the apnoeic threshold in heterozygous Mecp2-deficient female mice and examined the effects of blocking 5-HT reuptake on the CO2 response in Mecp2-null male mice. Studies were performed in B6.129P2(C)-Mecp2(τm1.1Bird) null males and heterozygous females. In an in situ preparation, seven of eight Mecp2-deficient heterozygous females showed arrest of phrenic nerve activity when arterial CO2 was lowered to 3%, whereas the wild-types maintained phrenic nerve amplitude at 53 ± 3% of maximal. In vivo plethysmography studies were used to determine CO2 chemosensitivity in null males. These mice were exposed sequentially to 1, 3 and 5% CO2. The percentage increase in minute ventilation in response to increased inspired CO2 was less in Mecp2(-/y) than in Mecp2(+/y) mice. Pretreatment with citalopram, a selective 5-HT reuptake inhibitor (2.5 mg kg(-1) i.p.), 40 min prior to CO2 exposure, in Mecp2(-/y) mice resulted in an improvement in CO2 chemosensitivity to wild-type levels. These results suggest that decreased 5-HT in Mecp2-deficient mice reduces CO2 chemosensitivity, and restoring 5-HT levels can reverse this effect.
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Affiliation(s)
- Marie A Toward
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR 97239, USA
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23
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Hagebeuk EEO, Bijlmer RPGM, Koelman JHTM, Poll-The BT. Respiratory disturbances in rett syndrome: don't forget to evaluate upper airway obstruction. J Child Neurol 2012; 27:888-92. [PMID: 22290859 DOI: 10.1177/0883073811429859] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Rett syndrome is characterized by loss of motor and social functions, development of stereotypic hand movements, seizures, and breathing disturbances. This study evaluates the presence of overnight respiratory disturbances. Polysomnography in combination with a questionnaire (the Sleep Disturbance Scale for Children) was performed in 12 Dutch patients with Rett. Respiratory disturbances were present in all, clinically relevant in 10 (apnea hypopnea per hour 1.0-14.5). In 8 children, central apneas were present during the day often with obstructive apneas at night. In 6, obstructive sleep apnea syndrome was diagnosed, in 3 severe, with frequent oxygen desaturations. Significant respiratory complaints were present in 3 patients, all had obstructive sleep apnea syndrome. Of the 12 patients with Rett, 8 (67%) snored, and in 5 obstructive sleep apnea syndrome was present. In children, hypertrophied tonsils and adenoids are a common cause of obstructive sleep apnea syndrome, which may benefit from therapeutic intervention. We recommend performing polysomnography in patients with Rett syndrome and respiratory complaints.
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Vermehren-Schmaedick A, Jenkins VK, Knopp SJ, Balkowiec A, Bissonnette JM. Acute intermittent hypoxia-induced expression of brain-derived neurotrophic factor is disrupted in the brainstem of methyl-CpG-binding protein 2 null mice. Neuroscience 2012; 206:1-6. [PMID: 22297041 DOI: 10.1016/j.neuroscience.2012.01.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/20/2011] [Accepted: 01/08/2012] [Indexed: 11/28/2022]
Abstract
Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding the transcription factor methyl-CpG-binding protein 2 (MeCP2). One of its targets is the gene encoding brain-derived neurotrophic factor (bdnf). In vitro studies using cultured neurons have produced conflicting results with respect to the role of MeCP2 in BDNF expression. Acute intermittent hypoxia (AIH) induces plasticity in the respiratory system characterized by long-term facilitation of phrenic nerve amplitude. This paradigm induces an increase in BDNF protein. We hypothesized that AIH leads to augmentation of BDNF transcription in respiratory-related areas of the brainstem and that MeCP2 is necessary for this process. Wild-type and mecp2 null (mecp2(-/y)) mice were subjected to three 5-min episodes of exposure to 8% O(2)/4% CO(2)/88% N(2), delivered at 5-min intervals. Normoxia control wild-type and mecp2 null mice were exposed to room air for the total length of time, that is, 30 min. Following a recovery in room air, the pons and medulla were rapidly removed. Expression of BDNF protein and transcripts were determined by ELISA and quantitative PCR, respectively. AIH induced a significant increase in BDNF protein in the pons and medulla, and in mRNA transcript levels in the pons of wild-type animals. In contrast, there were no significant changes in either BDNF protein or transcripts in the pons or medulla of mice lacking MeCP2. The results indicate that MeCP2 is required for regulation of BDNF expression by acute intermittent hypoxia in vivo.
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Affiliation(s)
- A Vermehren-Schmaedick
- Department of Integrative Biosciences, Oregon Health and Science University, Portland, OR 97239, USA
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Zhang X, Su J, Cui N, Gai H, Wu Z, Jiang C. The disruption of central CO2 chemosensitivity in a mouse model of Rett syndrome. Am J Physiol Cell Physiol 2011; 301:C729-38. [PMID: 21307341 PMCID: PMC3174562 DOI: 10.1152/ajpcell.00334.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 02/07/2011] [Indexed: 01/14/2023]
Abstract
People with Rett syndrome (RTT) have breathing instability in addition to other neuropathological manifestations. The breathing disturbances contribute to the high incidence of unexplained death and abnormal brain development. However, the cellular mechanisms underlying the breathing abnormalities remain unclear. To test the hypothesis that the central CO(2) chemoreception in these people is disrupted, we studied the CO(2) chemosensitivity in a mouse model of RTT. The Mecp2-null mice showed a selective loss of their respiratory response to 1-3% CO(2) (mild hypercapnia), whereas they displayed more regular breathing in response to 6-9% CO(2) (severe hypercapnia). The defect was alleviated with the NE uptake blocker desipramine (10 mg·kg(-1)·day(-1) ip, for 5-7 days). Consistent with the in vivo observations, in vitro studies in brain slices indicated that CO(2) chemosensitivity of locus coeruleus (LC) neurons was impaired in Mecp2-null mice. Two major neuronal pH-sensitive Kir currents that resembled homomeric Kir4.1 and heteromeric Ki4.1/Kir5.1 channels were identified in the LC neurons. The screening of Kir channels with real-time PCR indicated the overexpression of Kir4.1 in the LC region of Mecp2-null mice. In a heterologous expression system, an overexpression of Kir4.1 resulted in a reduction in the pH sensitivity of the heteromeric Kir4.1-Kir5.1 channels. Given that Kir4.1 and Kir5.1 subunits are also expressed in brain stem respiration-related areas, the Kir4.1 overexpression may not allow CO(2) to be detected until hypercapnia becomes severe, leading to periodical hyper- and hypoventilation in Mecp2-null mice and, perhaps, in people with RTT as well.
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Affiliation(s)
- Xiaoli Zhang
- Dept. of Biology, Georgia State Univ., Atlanta, 30303, USA
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Song G, Tin C, Giacometti E, Poon CS. Habituation without NMDA Receptor-Dependent Desensitization of Hering-Breuer Apnea Reflex in a Mecp2 Mutant Mouse Model of Rett Syndrome. Front Integr Neurosci 2011; 5:6. [PMID: 21629824 PMCID: PMC3096835 DOI: 10.3389/fnint.2011.00006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 04/12/2011] [Indexed: 01/20/2023] Open
Abstract
Non-associative learning is a basic neuroadaptive behavior exhibited in almost all animal species and sensory modalities but its functions and mechanisms in the mammalian brain are poorly understood. Previous studies have identified two distinct forms of non-associative learning in the classic Hering-Breuer inflation reflex (HBIR) induced apnea in rats: NMDA receptor (NMDAR)-independent habituation in a primary vagal pathway and NMDAR-dependent desensitization in a secondary pontine pathway. Here, we show that abnormal non-associative learning of the HBIR may underlie the endophenotypic tachypnea in an animal model of Rett syndrome (RTT), an autism-spectrum disorder caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MECP2). Mecp2(+/-) symptomatic mice on a mixed-strain background demonstrated significantly increased resting respiratory frequency with shortened expiration and normal inspiratory duration compared with asymptomatic mutants and wild-type controls, a phenotype that is characteristic of girls with RTT. Low-intensity electrical stimulation of the vagus nerve elicited fictive HBIR with time-dependent habituation in both Mecp2(+/-) and wild-type mice. However, time-dependent desensitization of the HBIR was evidenced only in wild-type controls and asymptomatic mutant mice but was absent or suppressed in Mecp2(+/-) symptomatic mice or in wild-type mice after blockade of NMDAR with dizocilpine. Remarkably, ∼50% of the Mecp2(+/-) mice developed these X-linked phenotypes despite somatic mosaicism. Such RTT-like respiratory endophenotypes in mixed-strain Mecp2(+/-) mice differed from those previously reported in Mecp2(-/y) mice on pure C57BL/6J background. These findings provide the first evidence indicating that impaired NMDAR-dependent desensitization of the HBIR may contribute to the endophenotypic tachypnea in RTT.
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Affiliation(s)
- Gang Song
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology Cambridge, MA, USA
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27
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Lioy DT, Wu WW, Bissonnette JM. Autonomic dysfunction with mutations in the gene that encodes methyl-CpG-binding protein 2: insights into Rett syndrome. Auton Neurosci 2011; 161:55-62. [PMID: 21316312 DOI: 10.1016/j.autneu.2011.01.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 01/12/2011] [Accepted: 01/18/2011] [Indexed: 11/30/2022]
Abstract
Rett syndrome (RTT) is an autism spectrum disorder with an incidence of ~1:10,000 females (reviewed in Bird, 2008; Chahrour et al., 2007; Francke, 2006). Affected individuals are apparently normal at birth. Between 6-18 months of age, however, RTT patients begin to exhibit deceleration of head growth, replacement of purposeful hand movements with stereotypic hand wringing, loss of speech, social withdrawal and other autistic features. RTT is caused by loss of function mutations in the gene that encodes methyl-CpG-binding protein 2 (Mecp2) (Amir et al., 1999), a transcriptional repressor that targets genes essential for neuronal survival, dendritic growth, synaptogenesis, and activity dependent plasticity. MECP2 is X-linked, and males die soon after birth. Included in the RTT phenotype are cardiorespiratory disorders involving the autonomic nervous system. The respiratory disorders, including the roles of bioaminergic and brain derived neurotrophic factor (BDNF) signaling in the respiratory pathophysiology of RTT have been recently reviewed (Bissonnette et al., 2007a; Ogier et al., 2008; Katz et al., 2009). Here we will cover the work on RTT regarding respiration that has appeared since 2009 as well as cardiovascular abnormalities.
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Affiliation(s)
- Daniel T Lioy
- Vollum Institute and Howard Hughes Medical Institute, Oregon Health and Science University, Portland, OR 97239, USA
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28
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Correction of respiratory disorders in a mouse model of Rett syndrome. Proc Natl Acad Sci U S A 2010; 107:18208-13. [PMID: 20921395 DOI: 10.1073/pnas.1012104107] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rett syndrome (RTT) is an autism spectrum disorder caused by mutations in the X-linked gene that encodes the transcription factor methyl-CpG-binding protein 2 (MeCP2). A major debilitating phenotype in affected females is frequent apneas, and heterozygous Mecp2-deficient female mice mimic the human respiratory disorder. GABA defects have been demonstrated in the brainstem of Mecp2-deficient mice. Here, using an intact respiratory network, we show that apnea in RTT mice is characterized by excessive excitatory activity in expiratory cranial and spinal nerves. Augmenting GABA markedly improves the respiratory phenotype. In addition, a serotonin 1a receptor agonist that depresses expiratory neuron activity also reduces apnea, corrects the irregular breathing pattern, and prolongs survival in MeCP2 null males. Combining a GABA reuptake blocker with a serotonin 1a agonist in heterozygous females completely corrects their respiratory defects. The results indicate that GABA and serotonin 1a receptor activity are candidates for treatment of the respiratory disorders in Rett syndrome.
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29
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De Felice C, Ciccoli L, Leoncini S, Signorini C, Rossi M, Vannuccini L, Guazzi G, Latini G, Comporti M, Valacchi G, Hayek J. Systemic oxidative stress in classic Rett syndrome. Free Radic Biol Med 2009; 47:440-8. [PMID: 19464363 DOI: 10.1016/j.freeradbiomed.2009.05.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 03/03/2009] [Accepted: 05/13/2009] [Indexed: 11/22/2022]
Abstract
Rett syndrome (RS), a progressive severe neurodevelopmental disorder mainly caused by de novo mutations in the X-chromosomal MeCP2 gene encoding the transcriptional regulator methyl-CpG-binding protein 2, is a leading cause of mental retardation with autistic features in females. However, its pathogenesis remains incompletely understood, and no effective therapy is available to date. We hypothesized that a systemic oxidative stress may play a key role in the pathogenesis of classic RS. Patients with classic RS (n=59) and control subjects (n=43) were evaluated. Oxidative stress markers included intraerythrocyte non-protein-bound iron (NPBI; i.e., free iron), plasma NPBI, F2-isoprostanes (F2-IsoPs, as free, esterified, and total forms), and protein carbonyls. Lung ventilation/perfusion (V/Q) ratio was assessed using a portable gas analyzer, and RS clinical severity was evaluated using standard scales. Significantly increased intraerythrocyte NPBI (2.73-fold), plasma NPBI (x 6.0), free F(2)-IsoP (x1.85), esterified F2-IsoP (x 1.69), total F2-IsoP (x 1.66), and protein carbonyl (x 4.76) concentrations were evident in RS subjects and associated with reduced (-10.53%) arterial oxygen levels compared to controls. Biochemical evidence of oxidative stress was related to clinical phenotype severity and lower peripheral and arterial oxygen levels. Pulmonary V/Q mismatch was found in the majority of the RS population. These data identify hypoxia-induced oxidative stress as a key factor in the pathogenesis of classic RS and suggest new therapeutic approaches based on oxidative stress modulation.
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Affiliation(s)
- Claudio De Felice
- Neonatal Intensive Care Unit, University Hospital AOUS of Siena, I-53100 Siena, Italy.
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Weese-Mayer DE, Lieske SP, Boothby CM, Kenny AS, Bennett HL, Ramirez JM. Autonomic dysregulation in young girls with Rett Syndrome during nighttime in-home recordings. Pediatr Pulmonol 2008; 43:1045-1060. [PMID: 18831533 DOI: 10.1002/ppul.20866] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study was designed to specifically characterize the autonomic phenotype of cardiorespiratory dysregulation during the nighttime in young girls with MECP2 mutation-confirmed Rett Syndrome (RS), studied in their home environment. Computerized breath-to-breath and beat-to-beat characterization of at-home continuously recorded respiratory inductance plethysmography of chest/abdomen and ECG (VivoMetrics, Inc.) was obtained during overnight recordings in 47 girls with MECP2 mutation-confirmed RS and 47 age-, gender-, and ethnicity-matched screened controls (ages 2-7 years). We determined that although the breathing and heart rate appear more regular during the night compared to the day, young girls with RS demonstrate apparent nocturnal irregularities. Comparing daytime versus nighttime, breathing was more irregular, with an increased breathing frequency (and irregularity), mean amplitude of respiratory inductance plethysmography sum (AMP)/T(I), and heart rate and decreased AMP in girls with RS. Comparing girls with RS versus controls during nighttime recording, breathing was more irregular, with an increased breathing frequency (and irregularity), mean AMP/T(I), and heart rate. An increased uncoupling between measures of breathing and heart rate control indicates malregulation in the autonomic nervous system, and is apparent during the day as well as the night. This uncoupling may represent a mechanism that renders the girls with RS more vulnerable to sudden death.
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Affiliation(s)
- Debra E Weese-Mayer
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois.,Center for Autonomic Medicine in Pediatrics, Children's Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Steven P Lieske
- Organismal Biology and Anatomy, University of Chicago Pritzker School of Medicine, Chicago, Illinois
| | - Christina M Boothby
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois
| | - Anna S Kenny
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois
| | - Heather L Bennett
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois
| | - Jan-Marino Ramirez
- Organismal Biology and Anatomy, University of Chicago Pritzker School of Medicine, Chicago, Illinois
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31
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Ogier M, Wang H, Hong E, Wang Q, Greenberg ME, Katz DM. Brain-derived neurotrophic factor expression and respiratory function improve after ampakine treatment in a mouse model of Rett syndrome. J Neurosci 2007; 27:10912-7. [PMID: 17913925 PMCID: PMC6672830 DOI: 10.1523/jneurosci.1869-07.2007] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Rett syndrome (RTT) is caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). Although MeCP2 is thought to act as a transcriptional repressor of brain-derived neurotrophic factor (BDNF), Mecp2 null mice, which develop an RTT-like phenotype, exhibit progressive deficits in BDNF expression. These deficits are particularly significant in the brainstem and nodose cranial sensory ganglia (NGs), structures critical for cardiorespiratory homeostasis, and may be linked to the severe respiratory abnormalities characteristic of RTT. Therefore, the present study used Mecp2 null mice to further define the role of MeCP2 in regulation of BDNF expression and neural function, focusing on NG neurons and respiratory control. We find that mutant neurons express significantly lower levels of BDNF than wild-type cells in vitro, as in vivo, under both depolarizing and nondepolarizing conditions. However, BDNF levels in mutant NG cells can be increased by chronic depolarization in vitro or by treatment of Mecp2 null mice with CX546, an ampakine drug that facilitates activation of glutamatergic AMPA receptors. Ampakine-treated Mecp2 null mice also exhibit marked functional improvement, characterized by restoration of normal breathing frequency and minute volume. These data demonstrate that BDNF expression remains plastic in Mecp2 null mice and raise the possibility that ampakine compounds could be of therapeutic value in the treatment of RTT.
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Affiliation(s)
- Michael Ogier
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, and
| | - Hong Wang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, and
| | - Elizabeth Hong
- Departments of Neurology and Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Qifang Wang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, and
| | - Michael E. Greenberg
- Departments of Neurology and Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - David M. Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, and
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Bissonnette JM, Knopp SJ. Effect of inspired oxygen on periodic breathing in methy-CpG-binding protein 2 (Mecp2) deficient mice. J Appl Physiol (1985) 2007; 104:198-204. [PMID: 18006868 DOI: 10.1152/japplphysiol.00843.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (Mecp2) that encodes a DNA binding protein involved in gene silencing. Periodic breathing (Cheyne-Stokes respiration) is commonly seen in RTT. Freely moving mice were studied with continuous recording of pleural pressure by telemetry. Episodes of periodic breathing in heterozygous Mecp2 deficient (Mecp2(+/-)) female mice (9.4 +/- 2.2 h(-1)) exceeded those in wild-type (Mecp2(+/+)) animals (2.5 +/- 0.4 h(-1)) (P = 0.010). Exposing Mecp2(+/-) animals to 40% oxygen increased the amount of periodic breathing from 118 +/- 25 s/30 min in air to 242 +/- 57 s/30 min (P = 0.001), and 12% oxygen tended to decrease it (67 +/- 29 s/30 min, P = 0.14). Relative hyperoxia and hypoxia did not affect the incidence of periodic breathing in Mecp2(+/+) animals. The ventilation/apnea ratio (V/A) was less at all levels of oxygen in heterozygous Mecp2(+/-) females compare with wild type (P = 0.003 to P < 0.001), indicating that their loop gain is larger. V/A in Mecp2(+/-) fell from 2.42 +/- 0.18 in normoxia to 1.82 +/- 0.17 in hyperoxia (P = 0.05) indicating an increase in loop gain with increased oxygen. Hyperoxia did not affect V/A in Mecp2(+/+) mice (3.73 +/- 0.28 vs. 3.5 +/- 0.28). These results show that periodic breathing in this mouse model of RTT is not dependent on enhanced peripheral chemoreceptor oxygen sensitivity. Rather, the breathing instability is of central origin.
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Affiliation(s)
- John M Bissonnette
- Department of Obstetrics and Gynecology, Oregon Health and Sciences University, Portland, Oregon 97239, USA.
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33
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Rohdin M, Fernell E, Eriksson M, Albåge M, Lagercrantz H, Katz-Salamon M. Disturbances in cardiorespiratory function during day and night in Rett syndrome. Pediatr Neurol 2007; 37:338-44. [PMID: 17950419 DOI: 10.1016/j.pediatrneurol.2007.06.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 05/14/2007] [Accepted: 06/14/2007] [Indexed: 10/22/2022]
Abstract
Rett syndrome causes severe autonomic dysregulation, probably due to brainstem dysfunction. Because the brainstem plays a decisive role in cardiorespiratory regulation during sleep, we investigated cardiorespiratory function in 12 girls with Rett syndrome, day and night, for 1 week in their home environment. Heart rate and breathing were recorded via standard three-lead electrocardiogram. Depth and frequency of respiratory movements were measured via changes in impedance. All children were scored clinically, and the association with cardiorespiratory function was examined. The total recording time for all patients was 1114 hours (535 during wakefulness; 579 during sleep), and 77 +/- 22 hours (median +/- standard error of the mean) per individual. All subjects manifested apnea, shallow breathing, or hypoventilation, when awake and during sleep. A majority had bradycardia or tachycardia. The frequencies of respiratory and heart alarms were similar during wakefulness and sleep. Bradycardia events predominated during sleep. The only significant correlation between clinical score and cardiorespiratory regulation was found for muscular-skeletal function and breathing abnormalities during wakefulness. We conclude that Rett syndrome is characterized by disturbed breathing and heart rate during sleep. The severity of cardiorespiratory dysfunction exhibited marked intra- and interindividual differences.
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Affiliation(s)
- Malin Rohdin
- Neonatal Unit Q2:09, Department of Woman and Child Health, Astrid Lindgren Children's Hospital, Karolinska Institutet, Stockholm, Sweden.
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34
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Stettner GM, Huppke P, Brendel C, Richter DW, Gärtner J, Dutschmann M. Breathing dysfunctions associated with impaired control of postinspiratory activity in Mecp2-/y knockout mice. J Physiol 2007; 579:863-76. [PMID: 17204503 PMCID: PMC2151368 DOI: 10.1113/jphysiol.2006.119966] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rett syndrome (RTT) is an inborn neurodevelopmental disorder caused by mutations in the X-linked methyl-CpG binding protein 2 gene (MECP2). Besides mental retardation, most patients suffer from potentially life-threatening breathing arrhythmia. To study its pathophysiology, we performed comparative analyses of the breathing phenotype of Mecp2-/y knockout (KO) and C57BL/6J wild-type mice using the perfused working heart-brainstem preparation (WHBP). We simultaneously recorded phrenic and efferent vagal nerve activities to analyse the motor pattern of respiration, discriminating between inspiration, postinspiration and late expiration. Our results revealed respiratory disturbances in KO preparations that were similar to those reported from in vivo measurements in KO mice and also to those seen in RTT patients. The main finding was a highly variable postinspiratory activity in KO mice that correlated closely with breathing arrhythmias leading to repetitive apnoeas even under undisturbed control conditions. Analysis of the pontine and peripheral sensory regulation of postinspiratory activity in KO preparations revealed: (i) prolonged apnoeas associated with enhanced postinspiratory activity after glutamate-induced activation of the pontine Kölliker-Fuse nucleus; and (ii) prolonged apnoeas and lack of reflex desensitization in response to repetitive vagal stimulations. We conclude that impaired network and sensory mediated synaptic control of postinspiration induces severe breathing dysfunctions in Mecp2-/y KO preparations. As postinspiration is particularly important for the control of laryngeal adductors, the finding might explain the upper airway-related clinical problems of patients with RTT such as apnoeas, loss of speech and weak coordination of breathing and swallowing.
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Affiliation(s)
- Georg M Stettner
- Department of Pediatrics and Pediatric Neurology, Georg August University, Robert-Koch-Str. 40, 37075 Göttingen, Germany
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35
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Weese-Mayer DE, Lieske SP, Boothby CM, Kenny AS, Bennett HL, Silvestri JM, Ramirez JM. Autonomic nervous system dysregulation: breathing and heart rate perturbation during wakefulness in young girls with Rett syndrome. Pediatr Res 2006; 60:443-9. [PMID: 16940240 DOI: 10.1203/01.pdr.0000238302.84552.d0] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study characterizes cardiorespiratory dysregulation in young girls with MECP2 mutation-confirmed Rett syndrome (RS). Respiratory inductance plethysmography of chest/abdomen and ECG was obtained during daytime wakefulness in 47 girls with MECP2 mutation-confirmed RS and 47 age-, gender-, and ethnicity-matched controls (ages 2-7 y). An in-home breath-to-breath and beat-to-beat characterization was conducted and revealed that breathing was more irregular, with an increased breathing frequency, mean airflow, and heart rate in RS versus controls. There was a decreased correlation between normal breathing and heart rate variability, and an exaggerated increase in heart rate response to breathholds in RS versus controls. We conclude that girls with RS have cardiorespiratory dysregulation during breathholds as well as during "normal" breaths and during breaths before and subsequent to breathholds. This dysregulation may offer insight into the mechanisms that render girls with RS more vulnerable to sudden death.
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Affiliation(s)
- Debra E Weese-Mayer
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois 60612, USA.
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36
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Abstract
The scope of pediatric autonomic disorders is not well recognized. The goal of this review is to increase awareness of the expanding spectrum of pediatric autonomic disorders by providing an overview of the autonomic nervous system, including the roles of its various components and its pervasive influence, as well as its intimate relationship with sensory function. To illustrate further the breadth and complexities of autonomic dysfunction, some pediatric disorders are described, concentrating on those that present at birth or appear in early childhood.
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Affiliation(s)
- Felicia B Axelrod
- Dysautonomia Treatment and Evaluation Center, Department of Pediatrics and Neurology, New York University School of Medicine, 530 First Ave, Suite 9Q, New York, New York 10016, USA.
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37
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Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2) that encodes a DNA binding protein involved in gene silencing. Selective deletion of Mecp2 in post-mitotic neurons in mice results in a Rett-like phenotype characterized by disturbances in motor activity and body weight, suggesting that these symptoms are exclusively caused by neuronal deficiency. Included in the RTT phenotype are episodes of respiratory depression that follow hyperventilation. Here we show that the respiratory phenotype depends on the organ distribution of Mecp2 deficiency. Both female mice heterozygous for a null mutation in Mecp2 (Mecp2+/-) and those with selective deletion of the protein in neurons (Mecp2+/nestin-Cre lox), showed an initial response to hypoxia that exceeded that in wild type (WT). However, marked respiratory depression following hypoxic hyperventilation was only seen in Mecp2+/- animals. Addition of carbon dioxide to the hypoxic exposure eliminated the respiratory depression. Tidal volume and lung volume were larger in Mecp2+/- and respiratory depression was directly related to tidal volume. Taken together these results indicate that the depression is due to hypocapnia. Respiratory depression in this mouse model of Rett Syndrome is seen in with ubiquitous deficiency in Mecp2 but not when it is confined to neurons.
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Affiliation(s)
- John M Bissonnette
- Department of Obstetrics and Gynecology, OR Health and Science University, Portland, OR 97239, USA.
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38
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Andaku DK, Mercadante MT, Schwartzman JS. Buspirone in Rett syndrome respiratory dysfunction. Brain Dev 2005; 27:437-8. [PMID: 15967617 DOI: 10.1016/j.braindev.2004.09.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Revised: 08/16/2004] [Accepted: 09/18/2004] [Indexed: 11/24/2022]
Abstract
This study details a case of Rett Syndrome where the patient's respiratory dysfunction was improved after buspirone was administered. Polygraphic studies in the waking state, before and after treatment with 5 mg of buspirone twice a day, were obtained. Breathing movements, oxygen saturation and end-tidal carbon were monitored. Average oxygen saturation increased from 86.9 to 91%, and the period of saturation below 90% was reduced by 42.2%. The oxygen saturation improvement observed in this case suggests that buspirone might be useful in treating respiratory dysfunction associated with Rett Syndrome. Controlled clinical trials are needed to provide more evidence.
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Affiliation(s)
- Daniela K Andaku
- Santo Amaro University Physical Therapy School, São Paulo, Brazil
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39
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Abstract
Rett syndrome is a neurodevelopmental disorder that in most cases is consequent to a mutation in the MECP2 gene. The central nervous system is the primary organ system involved in Rett syndrome. Neurophysiologic evaluations provide information concerning the developmental aspects of Rett syndrome and the character and extent of involvement of the central, peripheral, and autonomic nervous system pathways. Evoked potentials typically demonstrate intactness of peripheral auditory and visual pathways and suggest dysfunction of central or "higher" cortical pathways. Somatosensory evoked potentials can be characterized by "giant" responses, suggesting cortical hyperexcitability. Cortical hyperexcitability is further suggested by the findings of the electroencephalogram (EEG), which are primarily characterized by a loss of expected developmental features; the appearance of focal, multifocal, and generalized epileptiform abnormalities; and the occurrence of rhythmic slow (theta) activity, primarily in the frontal-central regions. Epileptic seizures are reported to occur frequently in Rett syndrome. However, many events presumed to be seizures have no EEG correlate during video-EEG monitoring. Impairment of the autonomic nervous system in Rett syndrome is suggested by an increased incidence of long Q-T intervals during electrocardiographic recordings and diminished heart rate variability. Autonomic nervous system dysfunction can contribute to the increased incidence of sudden unexpected death in Rett syndrome.
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Affiliation(s)
- Daniel G Glaze
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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Shahbazian MD, Zoghbi HY. Rett syndrome and MeCP2: linking epigenetics and neuronal function. Am J Hum Genet 2002; 71:1259-72. [PMID: 12442230 PMCID: PMC378559 DOI: 10.1086/345360] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 10/01/2002] [Indexed: 11/03/2022] Open
Affiliation(s)
- Mona D. Shahbazian
- Departments of Molecular and Human Genetics, Pediatrics, Neurology, and Neuroscience and Howard Hughes Medical Institute, Baylor College of Medicine, Houston
| | - Huda Y. Zoghbi
- Departments of Molecular and Human Genetics, Pediatrics, Neurology, and Neuroscience and Howard Hughes Medical Institute, Baylor College of Medicine, Houston
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Abstract
RS, the most common cause of profound cognitive impairment in girls and women, is composed of characteristic clinical features, including communication dysfunction, stereotypic movements, and pervasive growth failure. Neuropathologic findings indicate a failure of neuronal maturation with too small neurons and too few dendritic arbors and no evidence of a progressive neurodegenerative process. The combination of clinical and neuropathologic characteristics presents the profile of a neurodevelopmental disorder. Mutations in the gene MECP2, which encodes MeCP2, have been identified in 80% to 85% of girls and women with RS. Furthermore, the panorama of phenotypes with MECP2 mutations now extends far beyond RS to include normal girls and women, mild learning disability, autistic spectrum disorders, and X-linked mental retardation. These rapid advances in our understanding of RS over the past three decades have opened new avenues of study in developmental neurobiology.
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Affiliation(s)
- Alan K Percy
- Departments of Pediatrics, Neurology, and Neurobiology, University of Alabama, Birmingham School of Medicine, 1600 7th Avenue South, Suite 516, Birmingham, AL 35233, USA.
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Glaze DG. Neurophysiology of Rett syndrome. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 8:66-71. [PMID: 12112729 DOI: 10.1002/mrdd.10024] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Neurophysiological evaluations have been widely applied in the study of Rett syndrome (RS) to provide information concerning the developmental aspects of RS; the character and extent of involvement of the central, peripheral, and autonomic nervous system pathways; and evaluation of the clinical symptomatology of RS. The electroencephalogram (EEG) is invariably abnormal and shows characteristic, though not diagnostic, changes: loss of expected developmental features; the appearance of focal, multifocal, and generalized epileptiform abnormalities; and the occurrence of rhythmic slow (theta) activity primarily in the frontal-central regions. Epileptic seizures are reported to occur frequently in RS, and partial and generalized seizures may be experienced by RS girls. However, many events presumed to be seizures have no EEG correlate during video-EEG monitoring, suggesting the possibility of a nonepileptic mechanism. Such monitoring may be necessary to determine appropriate use of antiepileptic drugs. Evoked potentials typically demonstrate intact peripheral auditory and visual pathways and suggest dysfunction of central or "higher" cortical pathways. Somatosensory-evoked potentials may be characterized by "giant" responses, suggesting cortical hyperexcitability. An increased incidence of long QT intervals during electrocardiographic recordings and diminished heart-rate variability, suggesting impairment of the autonomic nervous system, are described in RS. With the discovery of the genetic basis of RS, neurophysiological studies will provide parameters for phenotype-genotype correlations and characterization of animal models.
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Affiliation(s)
- Daniel G Glaze
- Departments of Pediatrics and Neurology, Baylor College of Medicine, Houston, Texas 77030, USA.
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Percy AK. Clinical trials and treatment prospects. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 8:106-11. [PMID: 12112736 DOI: 10.1002/mrdd.10022] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Prospects for definitive therapeutic intervention for Rett syndrome (RS) have been elevated by the discovery of mutations in the methyl-CpG-binding protein 2 gene (MECP2) in more than 80% of females meeting clinical criteria for this disorder. As such, a review of previous clinical trials, descriptions of the status of clinical management for the prominent medical problems of RS, and a preview of an ongoing clinical trial conducted jointly at the Baylor College of Medicine and the University of Alabama at Birmingham are presented. The conduct of controlled clinical trials requires adherence to diagnostic criteria for RS; stratification by age, stage, and presence of MECP2 mutations; and use of clearly defined outcome measures. Previous clinical trials in RS have been conducted with L-carnitine, the ketogenic diet, and the opiate antagonist, naltrexone. The L-carnitine and naltrexone trials were double blind, placebo-controlled and us ed the motor behavioral analysis described in this review. All failed to provide evidence of dramatic improvements in the clinical features of RS. Specific recommendations are presented for clinical management of growth failure, breathing irregularities, seizures, ambulation, scoliosis, gastrointestinal function, self abuse, and habilitation/education although systematic evaluations of each in the context of RS have not been conducted. The only ongoing trial involves dietary supplementation with folate and betaine and is based on the finding that gene expression of some alleles of the agouti gene could be altered by dietary methyl supplementation. The availability of animal models expressing mutations in MECP2 should enhance the evaluation of innovative therapies for RS.
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Affiliation(s)
- Alan K Percy
- University of Alabama at Birmingham, School of Medicine, Birmingham, Alabama 35233, USA.
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Anzai Y, Ohya T. A case of effective gastrostomy for severe abdominal distention due to breathing dysfunction of Rett's syndrome: a treatment of autonomic disorder. Brain Dev 2001; 23 Suppl 1:S240-1. [PMID: 11738882 DOI: 10.1016/s0387-7604(01)00341-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We report a case of 13-year-old-girl with Rett's syndrome and effectiveness of gastrostomy for severe paradoxical respiration, seizures and abdominal distention. Since the age of 3, she was observed to have typical hand-washing movement and autistic behavior. At the age of 8, she began to have hyperventilation and seizures in awake stage. Her symptoms were worse from year to year. At the age of 13, gastrostomy was done to treat severe abdominal distention. Her symptoms were improve dramatically by the gastric air removal through gastrobutton.
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Affiliation(s)
- Y Anzai
- Department of Pediatrics. St. Luke's International Hospital, Tokyo, Japan
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Abstract
Neurophysiological studies on Rett syndrome (RTT) are reviewed, and pathophysiology of RTT is discussed. The electroencephalography (EEG), sensory evoked potentials (SEP), sleep-wake rhythm study and polysomnography (PSG) study showed age-dependent characteristics. PSG revealed the brainstem and midbrain monoaminergic systems are deranged from early developmental stage, that is serotonin and noradrenaline systems seem to be hypoactive and dopaminergic system is also hypoactive associated with receptor supersensitivity. These monoaminergic systems are known to influence the maturation of the higher neuronal systems at specific areas and at specific ages. Particularly the synaptogenesis of the cerebral cortex is modulated by region or layer specifically from an early stage of the development. The observations made in EEG and SEP studies also suggested specific subcortical and cortical involvements taking place during the development. The age-dependent appearance of characteristic clinical features of RTT, and the variation of the clinical severities, e.g. classical, variant, form fruste, etc., can also be explained by the specific features of these monoaminergic systems. Furthermore, analysis of the components of rapid eye movement sleep suggested the onset of RTT lies between 36 gestational weeks to 3-4 months postnatally. The discovery of the mutations of methyl-CpG-binding protein 2 (MECP2) gene as the causative gene of RTT is an epoch helping not only to understand the pathophysiology of RTT but also various neurodevelopmental disorders.
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Affiliation(s)
- Y Nomura
- Segawa Neurological Clinic for Children, 2-8 Surugadai, Kanda, Chiyoda-ku, 101-0062, Tokyo, Japan.
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Julu PO, Kerr AM, Apartopoulos F, Al-Rawas S, Engerström IW, Engerström L, Jamal GA, Hansen S. Characterisation of breathing and associated central autonomic dysfunction in the Rett disorder. Arch Dis Child 2001; 85:29-37. [PMID: 11420195 PMCID: PMC1718860 DOI: 10.1136/adc.85.1.29] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To investigate breathing rhythm and brain stem autonomic control in patients with Rett disorder. SETTING Two university teaching hospitals in the United Kingdom and the Rett Centre, Sweden. PATIENTS 56 female patients with Rett disorder, aged 2-35 years; 11 controls aged 5-28 years. DESIGN One hour recordings of breathing movement, blood pressure, ECG R-R interval, heart rate, transcutaneous blood gases, cardiac vagal tone, and cardiac sensitivity to baroreflex measured on-line with synchronous EEG and video. Breathing rhythms were analysed in 47 cases. RESULTS Respiratory rhythm was normal during sleep and abnormal in the waking state. Forced and apneustic breathing were prominent among 5-10 year olds, and Valsalva breathing in the over 18 year olds, who were also most likely to breathe normally. Inadequate breathing peaked among 10-18 year olds. Inadequate and exaggerated breathing was associated with vacant spells. Resting cardiac vagal tone and cardiac sensitivity to baroreflex were reduced. CONCLUSIONS Labile respiratory rhythms and poor integrative inhibition in Rett disorder suggest brain immaturity. Linking this to an early monoaminergic defect suggests possible targets for the MECP2 gene in clinical intervention. Exaggerated and inadequate autonomic responses may contribute to sudden death.
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Affiliation(s)
- P O Julu
- Peripheral Nerve and Autonomic Unit, Department of Neurology, Imperial College of Science, Technology and Medicine, Central Middlesex Hospital, Acton Lane, London NW10 7NS, UK.
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47
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Abstract
The recent identification of mutations in the gene methyl-Cpg-binding protein-2 (MECP2) in girls with Rett syndrome (RS) has firmly established the molecular genetic basis of this unique, X-linked, dominant disorder and provides a dramatic conclusion to an intensive, decade-long search. This finding has ramifications far beyond establishing the gene for RS. Recent data indicate that the clinical phenotypes for MECP2 mutations range from mild disability in the mother of a girl with RS to rapidly progressive encephalopathy in her brother. Further, the pathobiology of MECP2 could be a prototype for other disorders of neurodevelopment. MECP2 encodes a methyl-CpG-binding protein (MeCP2), which is critical for transcriptional silencing of an as yet unknown number and type of genes responsible for the pathobiology of RS. As such, this discovery opens up completely new vistas as to fundamental neurobiologic processes, to disease mechanisms in the neurodevelopmental disabilities, and to potential new therapeutic strategies for RS and related disorders.
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Affiliation(s)
- A K Percy
- Department of Pediatrics, University of Alabama at Birmingham, School of Medicine, 35233-1711, USA.
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Affiliation(s)
- A M Kerr
- Academic Centre, Department of Psychological Medicine, Glasgow University, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G12 0XH, UK
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Murakami Y, Yamashita Y, Matsuishi T, Iwanaga R, Kato H. Cerebral oxygenation and hemodynamics during hyperventilation and sleep in patients with Rett syndrome. Brain Dev 1998; 20:574-8. [PMID: 9865539 DOI: 10.1016/s0387-7604(98)00053-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We continuously monitored changes in cerebral oxygenation and hemodynamics in the frontal lobes of six patients with Rett syndrome during the awake state, which is associated with hyperventilation (HV) and breath-holding (BH), and during sleep by near-infrared spectroscopy. We also monitored three adult volunteers during simulated episodes of HV and BH. In patients with Rett syndrome, the oxygenated hemoglobin (HbO2) and total hemoglobin (HbT) decreased significantly during HV and BH in the awake state compared with the sleep state. The HbO2 and HbT decreased gradually in adult volunteers in response to prolonged episodes of HV and BH. Further studies are required to investigate the relationship, if any, between the discovered continuous decreases in HbO2 and HbT during the awake state and the brain damage seen in patients with Rett syndrome.
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Affiliation(s)
- Y Murakami
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume City, Fukuoka, Japan
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Cooper RA, Kerr AM, Amos PM. Rett syndrome: critical examination of clinical features, serial EEG and video-monitoring in understanding and management. Eur J Paediatr Neurol 1998; 2:127-35. [PMID: 10726834 DOI: 10.1016/s1090-3798(98)80028-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We studied data on seizures, vacant spells and breathing dysrhythmia from the British Rett Survey and 150 electroencephalographic records from 78 classic cases, including 23 with prolonged synchronous recordings of EEG, respiration and movement. The proportion of abnormal records increased from 6 of 18 (33%) during the first 6 months of the regression period to 44 of 59 (75%) in the later period to 6 years, the increase in abnormality following rather than preceding the onset of regression. In young girls the EEG abnormality increased in sleep but decreased during episodic hyperventilation and breath-holding. Epileptogenic activity was commonly present without clinical seizures. Eleven vacant spells were monitored and were not epileptic but related to the breathing abnormality. Full monitoring is essential when supposed seizures are intractable. The intermittent EEG abnormality and behavioural changes indicate abnormal fluctuating arousal possibly of midbrain or brainstem origin.
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Affiliation(s)
- R A Cooper
- University of Keele and North Staffordshire Hospital Group, UK
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