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Wang W, Ranjan A, Zhang W, Liang Q, MacMillan KS, Chapman K, Wang X, Chandrasekaran P, Williams NS, Rosenbaum DM, De Brabander JK. Novel orexin receptor agonists based on arene- or pyridine-fused 1,3-dihydro-2H-imidazole-2-imines. Bioorg Med Chem Lett 2024; 99:129624. [PMID: 38272190 DOI: 10.1016/j.bmcl.2024.129624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/15/2023] [Accepted: 01/18/2024] [Indexed: 01/27/2024]
Abstract
A structurally novel class of benzo- or pyrido-fused 1,3-dihydro-2H-imidazole-2-imines was designed and evaluated in an inositol phosphate accumulation assay for Gq signaling to measure agonistic activation of the orexin receptor type 2 (OX2R). These compounds were synthesized in 4-9 steps overall from readily available starting materials. Analogs that contain a stereogenic methyl or cyclopropyl substituent at the benzylic center, and a correctly configured alkyl ether, alkoxyalkyl ether, cyanoalkyl ether, or α-hydroxyacetamido substituted homobenzylic sidechain were identified as the most potent activators of OX2R coupled Gq signaling. Our results also indicate that agonistic activity was stereospecific at both the benzylic and homobenzylic stereogenic centra. We identified methoxyethoxy-substituted pyrido-fused dihydroimidazolimine analog 63c containing a stereogenic benzylic methyl group was the most potent agonist, registering a respectable EC50 of 339 nM and a maximal response (Emax) of 96 % in this assay. In vivo pharmacokinetic analysis indicated good brain exposure for several analogs. Our combined results provide important information towards a structurally novel class of orexin receptor agonists distinct from current chemotypes.
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Affiliation(s)
- Wentian Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Alok Ranjan
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Wei Zhang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Qiren Liang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Karen S MacMillan
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Karen Chapman
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA
| | - Xiaoyu Wang
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Preethi Chandrasekaran
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA
| | - Noelle S Williams
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA
| | - Daniel M Rosenbaum
- Department of Biophysics, University of Texas Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390-9041, USA.
| | - Jef K De Brabander
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9038, USA.
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Blackwell JE, Kingshott RN, Weighall A, Elphick HE, Nash H. Paediatric narcolepsy: a review of diagnosis and management. Arch Dis Child 2022; 107:7-11. [PMID: 33975822 DOI: 10.1136/archdischild-2020-320671] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 04/09/2021] [Accepted: 04/15/2021] [Indexed: 11/03/2022]
Abstract
Narcolepsy is a chronic disabling neurological sleep disorder that requires lifelong treatment. We have outlined the clinical features of narcolepsy, the assessment and diagnosis process and have summarised the existing treatment options for children and adolescents with narcolepsy. In the future, the approach to management of paediatric narcolepsy should ideally be in a multidisciplinary setting, involving specialists in sleep medicine, sleep physiology, neurologists and psychologists/psychiatrists. A multidisciplinary approach will help to manage the potential impact of narcolepsy on children and adolescents who are in a stage of their life that is critical to their physical, emotional and social development and their academic attainment.
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Affiliation(s)
- Jane Elizabeth Blackwell
- The Child Oriented Mental Health Intervention Centre, Leeds and York Partnership NHS Foundation Trust, York, UK
| | - Ruth N Kingshott
- Department of Respiratory Medicine, Sheffield Children's Hospital, Sheffield, UK
| | - Anna Weighall
- School of Education, The University of Sheffield, Sheffield, UK
| | - Heather E Elphick
- Department of Respiratory Medicine, Sheffield Children's Hospital, Sheffield, UK
| | - Hannah Nash
- School of Psychology, University of Leeds, Leeds, UK
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Des Roches A, Graham F, Begin P, Paradis L, Gold M. Evaluation of Adverse Reactions to Vaccines. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY-IN PRACTICE 2021; 9:3584-3597. [PMID: 34627533 DOI: 10.1016/j.jaip.2021.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 02/05/2023]
Abstract
The development and widespread use of vaccination over the past centuries has been the single most impactful intervention in public health, by effectively preventing morbidity and mortality from infectious diseases. Vaccination is generally well tolerated in the vast majority of the population, and the benefits of vaccination largely outweigh the risk of severe adverse events in the majority of patients. Vaccine hesitancy can be a significant concern and lead to infectious disease outbreaks. All health care providers play an important role in maintaining public confidence in vaccines because their attitude and knowledge is often critical in facilitating acceptance of a vaccine. The purpose of this review is to first, provide an understanding of the basic concepts that are relevant to vaccine pharmacovigilance, and secondly, to provide an overview and discuss management of both immune and nonimmune adverse events after vaccination.
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Affiliation(s)
- Anne Des Roches
- Department of Pediatrics, Service of Allergy and Clinical Immunology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada.
| | - François Graham
- Department of Pediatrics, Service of Allergy and Clinical Immunology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada; Department of Medicine, Service of Allergy and Clinical Immunology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada
| | - Philippe Begin
- Department of Pediatrics, Service of Allergy and Clinical Immunology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada; Department of Medicine, Service of Allergy and Clinical Immunology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada
| | - Louis Paradis
- Department of Pediatrics, Service of Allergy and Clinical Immunology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada; Department of Medicine, Service of Allergy and Clinical Immunology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada
| | - Michael Gold
- Discipline of Pediatrics, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
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Kreier F, Swaab DF. History of hypothalamic research: "The spring of primitive existence". HANDBOOK OF CLINICAL NEUROLOGY 2021; 179:7-43. [PMID: 34225985 DOI: 10.1016/b978-0-12-819975-6.00031-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The central brain region of interest for neuroendocrinology is the hypothalamus, a name coined by Wilhelm His in 1893. Neuroendocrinology is the discipline that studies hormone production by neurons, the sensitivity of neurons for hormones, as well as the dynamic, bidirectional interactions between neurons and endocrine glands. These interactions do not only occur through hormones, but are also partly accomplished by the autonomic nervous system that is regulated by the hypothalamus and that innervates the endocrine glands. A special characteristic of the hypothalamus is that it contains neuroendocrine neurons projecting either to the neurohypophysis or to the portal vessels of the anterior lobe of the pituitary in the median eminence, where they release their neuropeptides or other neuroactive compounds into the bloodstream, which subsequently act as neurohormones. In the 1970s it was found that vasopressin and oxytocin not only are released as hormones in the circulation but that their neurons project to other neurons within and outside the hypothalamus and function as neurotransmitters or neuromodulators that regulate central functions, including the autonomic innervation of all our body organs. Recently magnocellular oxytocin neurons were shown to send not only an axon to the neurohypophysis, but also axon collaterals of the same neuroendocrine neuron to a multitude of brain areas. In this way, the hypothalamus acts as a central integrator for endocrine, autonomic, and higher brain functions. The history of neuroendocrinology is described in this chapter from the descriptions in De humani corporis fabrica by Vesalius (1537) to the present, with a timeline of the scientists and their findings.
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Affiliation(s)
- Felix Kreier
- Department Pediatrics, OLVG Hospitals, Amsterdam, The Netherlands.
| | - Dick F Swaab
- Department Neuropsychiatric Disorders, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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Uzun N, Akıncı MA. Treatment of Isolated Cataplexy With Low-dose Aripiprazole in an Adolescent Patient. Clin Neuropharmacol 2020; 43:125-126. [PMID: 32590615 DOI: 10.1097/wnf.0000000000000398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cataplexy is a clinical entity that is characterized by transient muscle tone loss that mostly occurring as a part of narcolepsy. On the other hand, isolated cataplexy (IC) (hereditary cataplexy) is defined as loss of muscle tone that is not accompanied by narcolepsy. Emotional reactions may trigger IC episodes. Additionally, human leukocyte antigen (HLA) DQB1 alleles were shown to be related to IC. Various antidepressants are useful in the treatment of IC; however, there is limited knowledge on the use of antipsychotics in the treatment of IC. CASE REPORT A 16-year-old adolescent girl was consulted child and adolescent psychiatry outpatient clinic with complaint of sudden episodes of loss of muscle tone. Her HLA typing showed HLA DQB1*03 haplotype. She was diagnosed with IC and was prescribed aripiprazole 2.5 mg/d and her IC symptoms disappeared and never recurred over 6 months of follow-up. CONCLUSIONS In this case report, we present an adolescent girl with IC that is successfully treated with aripiprazole, an antipsychotic. This case report suggests that aripiprazole may be safely used in some adolescents who diagnosed with IC.
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Affiliation(s)
- Necati Uzun
- Department of Child and Adolescent Psychiatry, Necmettin Erbakan University Meram School of Medicine
| | - Mehmet Akif Akıncı
- Department of Child and Adolescent Psychiatry, Ali Kemal Belviranlı Maternity and Children Hospital, Konya, Turkey
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Ravel JM, Mignot EJM. [Narcolepsy: From the discovery of a wake promoting peptide to autoimmune T cell biology and molecular mimicry with flu epitopes]. Biol Aujourdhui 2019; 213:87-108. [PMID: 31829930 DOI: 10.1051/jbio/2019026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Indexed: 11/14/2022]
Abstract
Narcolepsy-cataplexy was first described in the late 19th century in Germany and France. Prevalence was established to be 0.05 % and a canine model was discovered in the 1970s. In 1983, a Japanese study found that all patients carried HLA-DR2, suggesting autoimmunity as the cause of the disease. Studies in the canine model established that dopaminergic stimulation underlies anti-narcoleptic action of psychostimulants, while antidepressants were found to suppress cataplexy through adrenergic reuptake inhibition. No HLA association was found in canines. A linkage study initiated in 1988 revealed in hypocretin (orexin) receptor two mutations as the cause of canine narcolepsy in 1999. In 1992, studies on African Americans showed that DQ0602 was a better marker than DR2 across all ethnic groups. In 2000, hypocretin-1/orexin A levels were measured in the cerebrospinal fluid (CSF) and found to be undetectable in most patients, establishing hypocretin deficiency as the cause of narcolepsy. Decreased CSF hypocretin-1 was then found to be secondary to the loss of the 70,000 neurons producing hypocretin in the hypothalamus, suggesting immune destruction of these cells as the cause of the disease. Additional genetic studies, notably genome wide associations (GWAS), found multiple genetic predisposing factors for narcolepsy. These were almost all involved in other autoimmune diseases, although a strong and unique association with T cell receptor (TCR) alpha and beta loci were observed. Nonetheless, all attempts to demonstrate presence of autoantibodies against hypocretin cells in narcolepsy failed, and the presumed autoimmune cause remained unproven. In 2009, association with strep throat infections were found, and narcolepsy onsets were found to occur more frequently in spring and summer, suggesting upper away infections as triggers. Following reports that narcolepsy cases were triggered by vaccinations and infections against influenza A 2009 pH1N1, a new pandemic strain that erupted in 2009, molecular mimicry with influenza A virus was suggested in 2010. This hypothesis was later confirmed by peptide screening showing higher activity of CD4+ T cell reactivity to a specific post-translationally amidated segment of hypocretin (HCRT-NH2) and cross-reactivity of specific TCRs with a pH1N1-specific segment of hemagglutinin that shares homology with HCRT-NH2. Strikingly, the most frequent TCR recognizing these antigens was found to carry sequences containing TRAJ24 or TRVB4-2, segments modulated by narcolepsy-associated genetic polymorphisms. Cross-reactive CD4+ T cells with these cross-reactive TCRs likely subsequently recruit CD8+ T cells that are then involved in hypocretin cell destruction. Additional flu mimics are also likely to be discovered since narcolepsy existed prior to 2009. The work that has been conducted over the years on narcolepsy offers a unique perspective on the conduct of research on the etiopathogeny of a specific disease.
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Affiliation(s)
- Jean-Marie Ravel
- Stanford Center for Sleep Sciences and Medicine, Department of Psychiatry and Behavioral Medicine, Stanford University, 3615 Porter Drive, Palo Alto, CA, USA
| | - Emmanuel J M Mignot
- Stanford Center for Sleep Sciences and Medicine, Department of Psychiatry and Behavioral Medicine, Stanford University, 3615 Porter Drive, Palo Alto, CA, USA
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Zhou F, Trieu MC, Davies R, Cox RJ. Improving influenza vaccines: challenges to effective implementation. Curr Opin Immunol 2018; 53:88-95. [DOI: 10.1016/j.coi.2018.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/08/2018] [Accepted: 04/13/2018] [Indexed: 12/15/2022]
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Abstract
Although narcolepsy was first described in the late nineteenth century in Germany and France, much of the research on this disorder has been conducted at Stanford University, starting with Drs. William C. Dement and Christian Guilleminault in the 1970s. The prevalence of narcolepsy was established, and a canine model discovered. Following the finding in Japan that almost all patients with narcolepsy carry a specific HLA subtype, HLA-DR2, Hugh Mac Devitt, F. Carl Grumet, and Larry Steinman initiated immunological studies, but results were generally negative. Using the narcoleptic canines, Dr. Nishino and I established that stimulants increased wakefulness by stimulating dopaminergic transmission while antidepressants suppress cataplexy via adrenergic reuptake inhibition. A linkage study was initiated with Dr. Grumet in 1988, and after 10 years of work, the canine narcolepsy gene was cloned by in 1999 and identified as the hypocretin (orexin) receptor 2. In 1992, studying African Americans, we also found that DQ0602 rather than DR2 was a better marker for narcolepsy across all ethnic groups. In 2000, Dr. Nishino and I, in collaboration with Dr. Lammers in the Netherlands, found that hypocretin 1 levels in the cerebrospinal fluid (CSF) were undetectable in most cases, establishing hypocretin deficiency as the cause of narcolepsy. Pursuing this research, our and Dr. Siegel's group, examining postmortem brains, found that the decreased CSF hypocretin 1 was secondary to the loss the 70,000 neurons producing hypocretin in the hypothalamus. This finding revived the autoimmune hypothesis but attempts at demonstrating immune targeting of hypocretin cells failed until 2013. At this date, Dr. Elisabeth Mellins and I discovered that narcolepsy is characterized by the presence of autoreactive CD4(+) T cells to hypocretin fragments when presented by DQ0602. Following reports that narcolepsy cases were triggered by vaccinations and infections against influenza A 2009 pH1N1, a new pandemic strain that erupted in 2009, our groups also established that a small epitope of pH1N1 resembles hypocretin and is likely involved in molecular mimicry. Although much remains to be done, these achievements, establishing hypocretin deficiency as the cause of narcolepsy, demonstrating its autoimmune basis, and showing molecular mimicry between hypocretin and sequences derived from a pandemic strain of influenza, are likely to remain classics in human immunology.
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Affiliation(s)
- Emmanuel J M Mignot
- Stanford University Center for Sleep Sciences, 3165 Porter Drive, #2178, Palo Alto, CA, 94304, USA,
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Orexin deficiency and narcolepsy. Curr Opin Neurobiol 2013; 23:760-6. [PMID: 23663890 DOI: 10.1016/j.conb.2013.04.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 04/10/2013] [Accepted: 04/10/2013] [Indexed: 11/24/2022]
Abstract
Orexin deficiency results in the sleep disorder narcolepsy in many mammalian species, including mice, dogs, and humans, suggesting that the orexin system is particularly important for normal regulation of sleep/wakefulness states, and especially for maintenance of wakefulness. This review discusses animal models of narcolepsy; the contribution of each orexin receptor subtype to the narcoleptic phenotypes; and the etiology of orexin neuronal death. It also raises the possibility of novel therapies targeting the orexin system for sleep disorders including insomia and narcolepsy-cataplexy.
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Tsujino N, Sakurai T. Role of orexin in modulating arousal, feeding, and motivation. Front Behav Neurosci 2013; 7:28. [PMID: 23616752 PMCID: PMC3629303 DOI: 10.3389/fnbeh.2013.00028] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/25/2013] [Indexed: 01/15/2023] Open
Abstract
Orexin deficiency results in narcolepsy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. However, orexin neurons are “multi-tasking” neurons that regulate sleep/wake states as well as feeding behavior, emotion, and reward processes. Orexin deficiency causes abnormalities in energy homeostasis, stress-related behavior, and reward systems. Orexin excites waking-active monoaminergic and cholinergic neurons in the hypothalamus and brain stem regions to maintain a long, consolidated waking period. Orexin neurons also have reciprocal links with the hypothalamic nuclei, which regulates feeding. Moreover, the responsiveness of orexin neurons to peripheral metabolic cues suggests that these neurons have an important role as a link between energy homeostasis and vigilance states. The link between orexin and the ventral tegmental nucleus serves to motivate an animal to engage in goal-directed behavior. This review focuses on the interaction of orexin neurons with emotion, reward, and energy homeostasis systems. These connectivities are likely to be highly important to maintain proper vigilance states.
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Affiliation(s)
- Natsuko Tsujino
- Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
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Orexin (hypocretin) receptor agonists and antagonists for treatment of sleep disorders. Rationale for development and current status. CNS Drugs 2013; 27:83-90. [PMID: 23359095 DOI: 10.1007/s40263-012-0036-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Orexin A and orexin B are hypothalamic neuropeptides initially identified as endogenous ligands for two orphan G-protein coupled receptors (GPCRs). They play critical roles in the maintenance of wakefulness by regulating function of monoaminergic and cholinergic neurons that are implicated in the regulation of wakefulness. Loss of orexin neurons in humans is associated with narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and cataplexy, further suggesting the particular importance of orexin in the maintenance of the wakefulness state. These findings have encouraged pharmaceutical companies to develop drugs targeting orexin receptors as novel medications of sleep disorders, such as narcolepsy and insomnia. Indeed, phase III clinical trials were completed last year of suvorexant, a non-selective (dual) antagonist for orexin receptors, for the treatment of primary insomnia, and demonstrate promising results. The New Drug Application (NDA) for suvorexant has been submitted to the US FDA. Thus, the discovery of a critical role played by the orexin system in the regulation of sleep/wakefulness has opened the door of a new era for sleep medicine.
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Isolated cataplexy in the differential diagnosis of drop attacks: a case of successful clinical diagnosis and treatment. Case Rep Neurol Med 2012; 2012:757586. [PMID: 22937359 PMCID: PMC3420411 DOI: 10.1155/2012/757586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/24/2012] [Indexed: 11/17/2022] Open
Abstract
Drop attacks are sudden spontaneous falls that are not accompanied by alteration of consciousness and are followed by immediate recovery. Cataplexy, which is usually associated with narcolepsy, is one of the causes of drop attacks. We report a patient with the rare condition of cataplexy without associated narcolepsy (isolated cataplexy). Isolated cataplexy should be included in the differential diagnosis when a patient presents with recurrent drop attacks and normal diagnostic test results.
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Sakurai T, Mieda M. Connectomics of orexin-producing neurons: interface of systems of emotion, energy homeostasis and arousal. Trends Pharmacol Sci 2011; 32:451-62. [PMID: 21565412 DOI: 10.1016/j.tips.2011.03.007] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/15/2011] [Accepted: 03/15/2011] [Indexed: 12/21/2022]
Abstract
Avoiding danger and finding food, which are life-sustaining activities that are regulated by emotion, reward and energy balance, require proper wakefulness. The orexin system controls sleep and wakefulness through interactions with systems that regulate emotion, reward and energy homeostasis. Recent findings have brought about the possibility of novel therapies targeting the orexin system for sleep disorders, including insomnia and narcolepsy-cataplexy, as well as other pathological conditions such as obesity and drug addiction [1]. In this review, we will discuss the current understanding of the integrative physiology and clinical perspectives of the orexin system. We will briefly review signaling through orexin A and B receptors and discuss the role of orexins in the pathophysiology of narcolepsy. We will also examine connections between orexin neurons and other brain areas involved in feeding behavior, reward and emotion. Finally, we will consider the therapeutic potential of drugs that target orexin receptors.
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Affiliation(s)
- Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8640, Japan. )
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Characterization of the major histocompatibility complex class II DOB, DPB1, and DQB1 alleles in cynomolgus macaques of Vietnamese origin. Immunogenetics 2010; 63:155-66. [PMID: 21132285 PMCID: PMC7080152 DOI: 10.1007/s00251-010-0498-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 11/16/2010] [Indexed: 12/20/2022]
Abstract
Major histocompatibility complex (MHC) molecules play an important role in the susceptibility and/or resistance to many diseases. To gain an insight into the MHC background and to facilitate the experimental use of cynomolgus macaques, the second exon of the MhcMafa-DOB, -DPB1, and -DQB1 genes from 143 cynomolgus macaques were characterized by cloning to sequencing. A total of 16 Mafa-DOB, 16 Mafa-DPB1, and 34 Mafa-DQB1 alleles were identified, which revealed limited, moderate, and marked allelic polymorphism at DOB, DPB1, and DQB1, respectively, in a cohort of cynomolgus macaques of Vietnamese origin. In addition, 16 Mafa-DOB, 5 Mafa-DPB1, and 8 Mafa-DQB1 alleles represented novel sequences that had not been reported in earlier studies. Almost of the sequences detected at the DOB and DQB1 locus in the present study belonged to DOB*01 (100%) and DQB1*06 (62%) lineages, respectively. Interestingly, four, three, and one high-frequency alleles were detected at Mafa-DOB, -DPB1, and -DQB1, respectively, in this monkeys. The alleles with the highest frequency among these monkeys were Mafa-DOB*010102, Mafa-DPB1*13, and Mafa-DQB1*0616, and these were found in 33 (25.6%) of 129 monkeys, 32 (31.37%) of 102 monkeys, and 30 (31%) of 143 monkeys, respectively. The high-frequency alleles may represent high priority targets for additional characterization of immune function. We also carried out evolutionary and population analyses using these sequences to reveal population-specific alleles. This information will not only promote the understanding of MHC diversity and polymorphism in the cynomolgus macaque but will also increase the value of this species as a model for biomedical research.
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Stepień A, Staszewski J, Domzał TM, Tomczykiewicz K, Skrobowska E, Durka-Kesy M. Degenerative pontine lesions in patients with familial narcolepsy. Neurol Neurochir Pol 2010; 44:21-7. [PMID: 20358482 DOI: 10.1016/s0028-3843(14)60403-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND PURPOSE Narcolepsy is characterized by chronic excessive daytime sleepiness with episodic sleep attacks. There are several associated symptoms of narcolepsy: cataplexy (bilateral muscle weakness without loss of consciousness provoked by an emotional trigger, e.g. laughter), sleep paralysis and hypnagogic-hypnopompic hallucinations. Most cases are sporadic; familial narcolepsy contributes to only 1-5% of all cases. While most cases of narcolepsy are idiopathic and are not associated with clinical or radiographic evidence of brain pathology, symptomatic or secondary narcolepsy may occur occasionally in association with lesions caused by tumours, demyelination or strokes of the diencephalon, midbrain, and pons. There are some examples of non-specific brainstem lesions found in magnetic resonance imaging (MRI) in patients with idiopathic narcolepsy. MATERIAL AND METHODS The authors present eleven patients from a five-generation family with many members who suffer from episodic excessive daytime sleepiness. Narcolepsy was diagnosed in 9 patients. Sleepiness was frequently associated with cataplexy, hypnagogic-hypnopompic hallucinations and sleep paralysis. Improvement in their clinical state was observed during the treatment with modafinil. All probands had MRI of the brain, routine blood tests, EEG, polysomnography, examination of the level of hypocretin in cerebrospinal fluid and evaluation by means of Epworth and Stanford Sleepiness Scales. RESULTS In 9 patients with narcolepsy, decreased thickness of the substantia nigra was found and in six of them degenerative lesions in the pontine substantia nigra were also noticed. CONCLUSIONS The significance of these changes remains unclear. No data have been published until now concerning the presence of any brain lesions in patients with familial narcolepsy.
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Affiliation(s)
- Adam Stepień
- Clinic of Neurology, Military Medical Institute, Szaserów St., Warsaw, Poland.
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Tsujino N, Sakurai T. Orexin/hypocretin: a neuropeptide at the interface of sleep, energy homeostasis, and reward system. Pharmacol Rev 2010; 61:162-76. [PMID: 19549926 DOI: 10.1124/pr.109.001321] [Citation(s) in RCA: 336] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent studies have implicated the orexin system as a critical regulator of sleep/wake states as well as feeding behavior and reward processes. Orexin deficiency results in narcolepsy in humans, dogs, and rodents, suggesting that the orexin system is particularly important for maintenance of wakefulness. In addition, orexin deficiency also cause abnormalities in energy homeostasis and reward systems. Orexin activates waking active monoaminergic and cholinergic neurons in the hypothalamus and brainstem regions to maintain a long, consolidated waking period. Orexin neurons receive abundant input from the limbic system. Orexin neurons also have reciprocal links with the hypothalamic arcuate nucleus, which regulates feeding. Moreover, the responsiveness of orexin neurons to peripheral metabolic cues, such as leptin and glucose, suggest that these neurons have important role as a link between the energy homeostasis and vigilance states. Orexin neurons also have a link with the dopaminergic reward system in the ventral tegmental nucleus. These findings suggest that the orexin system interacts with systems that regulate emotion, reward, and energy homeostasis to maintain proper vigilance states. Therefore, this system may be a potentially important therapeutic target for treatment of sleep disorder, obesity, emotional stress, and addiction.
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Affiliation(s)
- Natsuko Tsujino
- Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa-shi, Ishikawa 920-8640, Japan
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Kreier F, Swaab DF. Chapter 23: history of neuroendocrinology "the spring of primitive existence". HANDBOOK OF CLINICAL NEUROLOGY 2010; 95:335-360. [PMID: 19892126 DOI: 10.1016/s0072-9752(08)02123-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The history of neuroendocrinology is intimately related to one of the key questions, i.e. how does the brain manage to keep us alive and let our species survive? Neuroendocrinology, part of the answer to this question, is the discipline that studies hormone production by neurons, the sensitivity of neurons to hormones, and the dynamic, bidirectional interactions between neurons and endocrine glands. These interactions do not only occur through hormones, but are partly executed by the autonomic system that is regulated by the hypothalamus and that innervates not only the endocrine glands, but all our organs. The hypothalamus acts as a central integrator for endocrine, autonomic, and higher brain functions. The history of neuroendocrinology begins in 200 AD, with Galenus, who postulated that the brain excreted a residue from animal spirits (pituita), and continues into the last century, when researchers from different disciplines tried to understand how the brain regulates the vital functions of the body. Thanks to massive recent electronic publications of English and German scientific journals from the early 20th century we were able to rediscover fascinating articles, written in Europe before World War II, which showed that some of our most recent "innovative" concepts had in fact already been thought up some 50-100 years earlier. Apparently, World War II and the migration and exile of many researchers interrupted the development of concepts in this field and made rediscovery necessary. Our chapter gives an overview of the developments, both new and newly discovered.
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Affiliation(s)
- Felix Kreier
- Netherlands Institute for Neuroscience, Amsterdam, The Netherlands.
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Alaez C, Lin L, Flores-A H, Vazquez M, Munguia A, Mignot E, Haro R, Baker H, Gorodezky C. Association of narcolepsy-cataplexy with HLA-DRB1 and DQB1 in Mexican patients: a relationship between HLA and gender is suggested. BMC MEDICAL GENETICS 2008; 9:79. [PMID: 18706091 PMCID: PMC2533302 DOI: 10.1186/1471-2350-9-79] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 08/15/2008] [Indexed: 12/20/2022]
Abstract
Background Narcolepsy-cataplexy is characterized by excessive daytime sleepiness with recurrent episodes of irresistible sleep, cataplexy, hallucinations and sleep paralysis. Its aetiology is unknown, but it is positively associated with the human leukocyte antigens (HLA) in all studied populations. The purpose of the present study was to investigate the association of HLA class II DRB1/DQB1 alleles with narcolepsy-cataplexy in Mexican Mestizo patients. Methods This is a case-control study of consecutive patients and ethnically matched controls. We included 32 patients diagnosed with typical narcolepsy-cataplexy, of the National Institute of Neurology, of the Institute of Psychiatry and at the Center of Narcolepsy at Stanford University. As healthy controls, 203 Mexican Mestizos were included. DRB1 alleles were identified using sequence based typing. A PCR-SSOP reverse dot blot was used for DQB1 typing. Allele frequency was calculated by direct counting and the significance of the differences was assessed using the Yates Chi square. Odds ratio and confidence intervals were evaluated. Results HLA-DRB1*1501 (OR = 8.2; pc < 0.0001) and DQB1*0602 (OR = 8.4; pc < 0.0001) were found positively associated with narcolepsy. When deleting DQB1*0602+ patients from the analysis, DQB1*0301 was also found increased (OR = 2.7; p = 0.035; pc = NS). DQB1*0602/DQB1*0301 genotype was present in 15.6% of the cases (OR = 11.5; p = 0.00035), conferring a high risk. DRB1*0407 (OR = 0.2; p = 0.016 pc = NS) and DQB1*0302(OR = 0.4; p = 0.017, pc = NS) were found decreased in the patients. The gender stratification analysis showed a higher risk in females carrying DRB1*1501 (OR = 15.8, pc < 0.0001) and DQB1*0602 (OR = 19.8, pc < 0.0001) than in males (OR = 5.0 for both alleles; p = 0.012, pc = NS for DRB1 & p = 0.0012, pc = 0.017 for DQB1). The susceptibility alleles found in Mexicans with narcolepsy are also present in Japanese and Caucasians; DRB1*04 linked protection has also been shown in Koreans. A stronger HLA association is suggested in females, in accordance with the sexual dimorphism claimed previously. Conclusion This knowledge may contribute to a better understanding of the disease pathogenesis in different populations. The evaluation of the risk to develop narcolepsy-cataplexy in carriers of the described alleles/genotypes may also be possible. A larger sample should be analysed in Mexican and in other Hispanic patients to confirm these results.
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Affiliation(s)
- Carmen Alaez
- Department of Immunology and Immunogenetics, InDRE, Mexico City, Mexico.
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22
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Abstract
Narcolepsy with cataplexy is a debilitating sleep disorder with an estimated prevalence of about 0.05%. Narcolepsy is caused by a selective loss of hypocretin (orexin) producing neurons in the perifornical hypothalamus. Based on the very strong association with the HLA subtype DQB1*0602, it is currently hypothesized narcolepsy is caused by an autoimmune-mediated process directed at the hypocretin neurons. So far however, studies focusing on general markers of (auto)immune activation, as well as humoral immunity against the hypocretin system have not yielded consistent results supporting this hypothesis.
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Affiliation(s)
- Sebastiaan Overeem
- Department of Neurology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
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23
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Ohno K, Sakurai T. Orexin neuronal circuitry: role in the regulation of sleep and wakefulness. Front Neuroendocrinol 2008; 29:70-87. [PMID: 17910982 DOI: 10.1016/j.yfrne.2007.08.001] [Citation(s) in RCA: 201] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 08/06/2007] [Accepted: 08/08/2007] [Indexed: 11/26/2022]
Abstract
Orexin A and orexin B were initially identified as endogenous ligands for two orphan G protein-coupled receptors [104]. They were initially recognized as regulators of feeding behavior in view of their exclusive production in the lateral hypothalamic area (LHA), a region known as the feeding center, and their pharmacological activity [104,30,49,107]. Subsequently, the finding that orexin deficiency causes narcolepsy in humans and animals suggested that these hypothalamic neuropeptides play a critical role in regulating sleep/wake cycle [22,46,71,95,117]. These peptides activate waking-active monoaminergic and cholinergic neurons in the hypothalamus/brain stem regions to maintain a long, consolidated awake period. Recent studies on efferent and afferent systems of orexin neurons, and phenotypic characterization of genetically modified mice in the orexin system further suggested roles of orexin in the coordination of emotion, energy homeostasis, reward system, and arousal [3,80,106,137]. A link between the limbic system and orexin neurons might be important for increasing vigilance during emotional stimuli. Orexin neurons are also regulated by peripheral metabolic cues, including ghrelin, leptin, and glucose, suggesting that they might have important roles as a link between energy homeostasis and vigilance states [137]. Recent research has also implicated orexins in reward systems and the mechanisms of drug addiction [13,48,91]. These observations suggest that orexin neurons sense the outer and inner environment of the body, and maintain proper wakefulness of animals for survival. This review discusses the mechanism by which orexins maintain sleep/wakefulness states, and how this mechanism relates to other systems that regulate emotion, reward, and energy homeostasis.
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Affiliation(s)
- Kousaku Ohno
- Department of Pharmacology, Institute of Basic Medical Science, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
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Sakurai T. The neural circuit of orexin (hypocretin): maintaining sleep and wakefulness. Nat Rev Neurosci 2007; 8:171-81. [PMID: 17299454 DOI: 10.1038/nrn2092] [Citation(s) in RCA: 857] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Sleep and wakefulness are regulated to occur at appropriate times that are in accordance with our internal and external environments. Avoiding danger and finding food, which are life-essential activities that are regulated by emotion, reward and energy balance, require vigilance and therefore, by definition, wakefulness. The orexin (hypocretin) system regulates sleep and wakefulness through interactions with systems that regulate emotion, reward and energy homeostasis.
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Affiliation(s)
- Takeshi Sakurai
- Department of Pharmacology, Institute of Basic Medical Science, University of Tsukuba, Ibaraki 305-8575, Japan.
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25
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Swaab DF. The human hypothalamus in metabolic and episodic disorders. PROGRESS IN BRAIN RESEARCH 2006; 153:3-45. [PMID: 16876566 DOI: 10.1016/s0079-6123(06)53001-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- D F Swaab
- Netherlands Institute for Neuroscience, Meibergdreef 47, 1105BA Amsterdam, The Netherlands.
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26
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Abstract
Orexins, which were initially identified as endogenous peptide ligands for two orphan G-protein coupled receptors (GPCRs), have been shown to have an important role in the regulation of energy homeostasis. Furthermore, the discovery of orexin deficiency in narcolepsy patients indicated that orexins are highly important factors for the sleep/wakefulness regulation. The efferent and afferent systems of orexin-producing neurons suggest interactions between these cells and arousal centers in the brainstem as well as important feeding centers in the hypothalamus. Electrophysiological studies have shown that orexin neurons are regulated by humoral factors, including leptin, glucose, and ghrelin as well as monoamines and acetylcholin. Thus, orexin neurons have functional interactions with hypothalamic feeding pathways and monoaminergic/cholinergic centers to provide a link between peripheral energy balance and the CNS mechanisms that coordinate sleep/wakefulness states and motivated behavior such as food seeking.
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Affiliation(s)
- Takeshi Sakurai
- Department of Pharmacology, Institute of Basic Medical Science, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
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27
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Thompson MD, Comings DE, Abu-Ghazalah R, Jereseh Y, Lin L, Wade J, Sakurai T, Tokita S, Yoshida T, Tanaka H, Yanagisawa M, Burnham WM, Moldofsky H. Variants of the orexin2/hcrt2 receptor gene identified in patients with excessive daytime sleepiness and patients with Tourette's syndrome comorbidity. Am J Med Genet B Neuropsychiatr Genet 2004; 129B:69-75. [PMID: 15274044 DOI: 10.1002/ajmg.b.30047] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The orexin-2/hypocretin-2 (OX2R) receptor gene is mutated in canine narcolepsy and disruption of the prepro-orexin/hypocretin ligand gene results in both an animal model of narcolepsy and sporadic cases of the human disease. This evidence suggests that the structure of the OX2R gene, and its homologue, the OX1R gene, both members of the G protein-coupled receptor (GPCR) family, and the gene encoding the peptide ligands, the prepro-orexin/hypocretin gene, may be variables in the etiology of sleep disorders. We report a single stranded conformational polymorphism (SSCP) analysis of the coding regions of these genes in idiopathic sleep disorder patients diagnosed with excessive daytime sleepiness (EDS) (n = 28), narcolepsy (n = 28), Tourette's syndrome/chronic vocal or motor tic disorder (n = 70), and control subjects (n = 110). Two EDS patients showed a Pro11Thr change. One Tourette's syndrome patient was found to have a Pro10Ser alteration. The Pro10Ser and Pro11Thr variants were not found in non-disease populations. Analysis of the ability of the mutant receptors to mobilize calcium compared to the wild-type receptor in response to orexin agonists indicated that they resulted in decreased potency at high (etaM) concentrations of orexin ligands. Further work is warranted to study the variability of the orexin/hypocretin system in a variety of disorders characterized by EDS.
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Affiliation(s)
- Miles D Thompson
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada.
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Abstract
A few examples of hypothalamic, peptidergic disorders leading to clinical signs and symptoms are presented in this review. Increased activity of corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN) and decreased activity of the vasopressin neurons in the biological clock and of the thyroxine-releasing hormone (TRH) neurons in the PVN contribute to the signs and symptoms of depression. In men, the central nucleus of the bed nucleus of the stria terminalis (BSTc) is about twice as large and contains twice as many somatostatin neurons as in women. In transsexuals this sex difference is reversed, pointing to a role of this structure in gender. Luteinizing hormone-releasing hormone (LHRH) neurons are formed in the fetal olfactory placade and migrate along the terminal nerve fibers into the hypothalamus. In Kallmann's syndrome the migration process of the LHRH (gonadotropin-releasing hormone) neurons is aborted, which explains the joint occurrence of hypogonadotropic hypogonadism and anosmia in this syndrome. In postmenopausal women, the neurons of the infundibular nucleus hypertrophy and become hyperactive because of the disappearance of the estrogen feedback and contain hyperactive peptidergic neurons. Climacteric flushes may be caused by hyperactivity of the neurokinin-B or LHRH neurons in this nucleus. The hypocretin (orexin) neurons in the perifornical area are involved in sleep. In narcolepsy with cataplexy, a loss of these neurons, probably due to an autoimmune process, is found. Obese subjects with a mutation in the gene that encodes for leptin, the preproghrelin gene, or the alpha-melanocyte-stimulating hormone (alpha-MSH) gene have been described. Decreased numbers and activity of the oxytocin neurons in the PVN may be responsible for the absence of satiety in Prader-Willi syndrome. Moreover, a glucocorticoid receptor polymorphism is associated with obesitas and dysregulation of the hypothalamus-pituitary-adrenal axis. In contrast, two single nucleotide polymorphisms (SNPs) of the AGRP gene have been associated with anorexia nervosa.
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Affiliation(s)
- Dick F Swaab
- Netherlands Institute for Brain Research, 1105 AZ, Amsterdam, The Netherlands
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29
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Abstract
Human narcolepsy is a genetically complex disorder. Family studies indicate a 20-40 times increased risk of narcolepsy in first-degree relatives and twin studies suggest that nongenetic factors also play a role. The tight association between narcolepsy-cataplexy and the HLA allele DQB1*0602 suggests that narcolepsy has an autoimmune etiology. In recent years, extensive genetic studies in animals, using positional cloning in dogs and gene knockouts in mice, have identified abnormalities in hypothalamic hypocretin (orexin) neurotransmission as key to narcolepsy pathophysiology. Though most patients with narcolepsy-cataplexy are hypocretin deficient, mutations or polymorphisms in hypocretin-related genes are extremely rare. It is anticipated that susceptibility genes that are independent of HLA and impinge on the hypocretin neurotransmitter system are isolated in human narcolepsy.
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Affiliation(s)
- Dorothee Chabas
- Federation de neurologie, Batiment Paul Castaigne, Hopital Salpetriere, 47-83 Boulevard de l'hopital, 75 013 Paris, France.
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30
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Abstract
Maintenance of energy homeostasis requires the coordination of systems that regulate feeding, autonomic and endocrine functions with those that govern an appropriate state of arousal. The hypothalamus play a critical role in maintaining energy homeostasis by integrating and coordinating these systems. Recent studies have suggested that orexin-containing neurons in the lateral hypothalamic area constitute an important central pathway that promotes adaptive behavioral and arousal responses to metabolic and environmental signals. This article review recent studies on orexin to suggest that orexin neurons play a significant role in feeding and arousal regulation, possibly by coordinating the complex behavioral and physiological responses of these complementary homeostatic functions.
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Affiliation(s)
- Takeshi Sakurai
- Department of Pharmacology, Institute of Basic Medical Science, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8575, Japan.
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Abstract
The heritability of self-reported sleep patterns was investigated with 86 identical and 78 fraternal same-sex and 51 fraternal mixed-gender adult twin pairs who were paid to maintain 7-day diaries. Linear structural modeling was applied to investigate the nature and degree of genetic and environmental influences and revealed significant genetic influences on the time that individuals went to sleep and woke up, how often the individual woke up during the night, the duration of sleep and wakefulness, and how alert the individual felt upon waking and over the day, accounting for 21% to 41% of the variance. These influences of heredity were present for sleep-wake behavior over the entire week and also when the sleep-wake pattern was analyzed separately for weekdays and weekends. Further, it was demonstrated that there were multiple independent influences of heredity on sleep-wake behavior. The results suggest that sleep-wake patterns are not learned but result in part from multiple heritable influences.
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Affiliation(s)
- John M de Castro
- Neuropsychology and Behavioral Neuroscience Program, Department of Psychology, College of Arts and Sciences, Georgia State University, University Plaza, Atlanta, GA 30303-3083, USA.
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Abstract
Maintenance of energy homeostasis requires the coordination of systems that regulate feeding, body temperature, autonomic and endocrine functions with those that govern an appropriate state of arousal (wakefulness). Historically, the hypothalamus has been recognized to play a critical role in maintaining energy homeostasis by integrating these factors and coordinating metabolic, neuroendocrine and behavioral responses and arousal states. Recent studies have suggested that orexin-containing neurons in the lateral hypothalamic area (LHA) constitute an important central pathway that promotes adaptive behavioral and arousal responses to metabolic and environmental signals. Orexins, also called hypocretins, are neuropeptides originally identified as endogenous ligands for two orphan G-protein-coupled receptors termed orexin receptors -1 and -2. Orexin-A and -B are expressed by a specific population of neurons in the LHA. These neurons project to numerous brain regions, with monoaminergic and cholinergic nuclei of the hypothalamus, midbrain, and pons receiving particularly strong innervations. The orexinergic system is anatomically well-placed to coordinate the metabolic, motivational, motor, autonomic, and arousal processes necessary to elicit environmentally appropriate behaviors. Recent studies on orexin suggest that the orexinergic system plays a significant role in feeding and sleep-wakefulness regulation, possibly by coordinating the complex behavioral and physiological responses of these complementary homeostatic functions. Orexin neurons may provide an integrative link between peripheral metabolism and central regulation of behaviors required for an adaptive response to homeostatic challenges.
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Affiliation(s)
- Takeshi Sakurai
- Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
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Abstract
Narcolepsy was first shown to be tightly associated with HLA-DR2 and DQ1 in 1983, suggesting a possible autoimmune mechanism. Early investigations failed to demonstrate this hypothesis, postulating that HLA-DR2 was only a linkage marker for another, unknown narcolepsy-causing gene. The autoimmune hypothesis is now being re-evaluated under the light of recent results. Like many other autoimmune disorders, narcolepsy usually starts during adolescence, is human leukocyte antigen (HLA)-associated, multigenic and environmentally influenced. Furthermore, HLA-association studies indicated a primary HLA-DQ effect with complex HLA class II allele interactions and a partial contribution of HLA to overall genetic susceptibility. Finally, recent result suggests that human narcolepsy is associated with the destruction of a small number of hypothalamic neurons containing the peptide hypocretins (orexins). This data is consistent with an immune destruction of hypocretin-containing cells as the most common etiology for human narcolepsy.
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Affiliation(s)
- L Lin
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Narcolepsy, Stanford University Medical Center, 1201 Welch Road, P-114, Palo Alto, CA 94305-5485, USA
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Petitto JM, Repetto MJ, Hartemink DA. Brain-immune interactions in neuropsychiatry: highlights of the basic science and relevance to pathogenic factors and epiphenomena. CNS Spectr 2001; 6:383-8, 391. [PMID: 15999026 DOI: 10.1017/s1092852900021751] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Unraveling the significant complexity of brain-immune interactions could provide essential new insights and potential treatment considerations for the clinical neurosciences. Despite considerable research relating immunological changes to major neuropsychiatric disorders, it has been difficult to establish that immunological processes are involved in the development of central nervous system pathology associated with these disorders. This brief article highlights some of the landmark basic studies and seeks to convey essential principles guiding research in brain-immune interactions. Research in this area often incorporates several disciplines, ranging from psychology and neuroscience to immunology and molecular genetics. The clinical implications of this area of research are discussed, with emphasis on the challenge of disentangling pathogenic factors and valid markers of disease from epiphenomena.
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Affiliation(s)
- J M Petitto
- Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL 32610-0256, USA.
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Hara J, Beuckmann CT, Nambu T, Willie JT, Chemelli RM, Sinton CM, Sugiyama F, Yagami K, Goto K, Yanagisawa M, Sakurai T. Genetic ablation of orexin neurons in mice results in narcolepsy, hypophagia, and obesity. Neuron 2001; 30:345-54. [PMID: 11394998 DOI: 10.1016/s0896-6273(01)00293-8] [Citation(s) in RCA: 993] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Orexins (hypocretins) are a pair of neuropeptides implicated in energy homeostasis and arousal. Recent reports suggest that loss of orexin-containing neurons occurs in human patients with narcolepsy. We generated transgenic mice in which orexin-containing neurons are ablated by orexinergic-specific expression of a truncated Machado-Joseph disease gene product (ataxin-3) with an expanded polyglutamine stretch. These mice showed a phenotype strikingly similar to human narcolepsy, including behavioral arrests, premature entry into rapid eye movement (REM) sleep, poorly consolidated sleep patterns, and a late-onset obesity, despite eating less than nontransgenic littermates. These results provide evidence that orexin-containing neurons play important roles in regulating vigilance states and energy homeostasis. Orexin/ataxin-3 mice provide a valuable model for studying the pathophysiology and treatment of narcolepsy.
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Affiliation(s)
- J Hara
- Department of Pharmacology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
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Abstract
Recently, low levels of a newly identified neuropeptide, hypocretin 1, were described in the cerebrospinal fluid of patients with narcolepsy. This neurochemical finding furthers our understanding of this enigmatic sleep disorder typically characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations. Narcolepsy appears to be fundamentally related to abnormally regulated rapid eye movement sleep. The diagnosis of this disorder remains challenging because of multiple other conditions that can cause daytime sleepiness and the difficulties in recognizing cataplexy based on patient report. The role of hypocretins in narcolepsy is unclear but intriguing because the cell bodies are restricted to the lateral hypothalamus, a brain region long associated with sleep regulation, with neuronal widespread projections to areas including the locus ceruleus, ventral tegmental area, amygdala, and dorsal raphe. Hypocretins potentially modulate the activity of monoamines and acetylcholine, and therefore their absence leads to the multiple symptoms of narcolepsy. This article reviews the current understanding of the diagnosis and treatment of narcolepsy and discusses the possible implications of the hypocretin discovery.
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Affiliation(s)
- L E Krahn
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minn. 55905, USA.
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37
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Abstract
Background and purpose: Narcolepsy is the most common neurologic cause of excessive daytime sleepiness. Rapid eye movement (REM) sleep phenomena such as cataplexy, sleep paralysis and hypnagogic hallucinations can also occur. Cataplexy, a sudden bilateral loss of muscle tone usually brought on by emotional reactions such as excitement, is essentially unique to narcolepsy. Narcolepsy, which has a prevalence of 0.02-0.05% in the US, has a profound influence on the quality of life and safety of affected individuals.Patients and methods: The most characteristic and striking physiological abnormality observed in narcolepsy is the sleep-onset REM, or the occurrence of REM sleep at, or within 20 min of, the onset of sleep. The diagnosis is established by nocturnal polysomnography, and the Multiple Sleep Latency Test (MSLT).Results: Familial cases of narcolepsy have been reported, with the risk to first-degree relatives estimated at 1-2%; however, most cases are sporadic and the syndrome is generally believed to involve environmental factors acting on a specific genetic background. The observation of an HLA association in narcolepsy suggests that autoimmunity may play a role in the disorder. However, extensive studies have failed to find convincing evidence of an autoimmune process. Patients with narcolepsy have recently been shown to be deficient in hypocretin, also called orexin, in the cerebrospinal fluid and have a reduction in hypocretin cells in the lateral hypothalamus. This suggests that hypocretins could potentially provide a novel therapeutic approach to the treatment of narcolepsy.Conclusions: Although non-pharmacologic measures can be helpful in treating narcolepsy, most patients require pharmacotherapy that includes psychostimulants or modafinil. Cataplexy is controlled by tricyclic antidepressants or selective serotonin reuptake inhibitors.
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Affiliation(s)
- M Thorpy
- Montefiore Medical Center, 111 East 210th Street, NY 10467-2490, Bronx, USA
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38
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Pathophysiological and clinical aspects of narcolepsy: a disorder associated with hypocretin abnormalities. SOMNOLOGIE 2000. [DOI: 10.1007/s11818-000-0002-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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39
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Abstract
Newly described peptides, produced in neurons in the lateral hypothalamic area, have been shown to stimulate appetite and stereotypic behaviors associated with feeding. Discovered independently by two groups, the hypocretins/orexins stimulate autonomic function and have been shown to be physiological regulators of the arousal state. Neuroendocrine and metabolic effects of these peptides, some related to sleep-wakefulness and arousal state, are just now being discovered.
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Affiliation(s)
- W K Samson
- Department of Pharmacological and Physiological Sciences, Saint Louis University School of Medicine, 1402 South Grand Boulevard, St Louis, MO 63131, USA.
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Pavelko KD, Drescher KM, McGavern DB, David CS, Rodriguez M. HLA-DQ polymorphism influences progression of demyelination and neurologic deficits in a viral model of multiple sclerosis. Mol Cell Neurosci 2000; 15:495-509. [PMID: 10860577 PMCID: PMC5450945 DOI: 10.1006/mcne.2000.0843] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The importance of genetic susceptibility in determining the progression of demyelination and neurologic deficits is a major focus in neuroscience. We studied the influence of human leukocyte antigen (HLA)-DQ polymorphisms on disease course and neurologic impairment in virus-induced demyelination. HLA-DQ6 or DQ8 was inserted as a transgene into mice lacking endogenous expression of MHC class I (beta(2)m) and class II (H2-A(beta)) molecules. Following Theiler's murine encephalomyelitis virus (TMEV) infection, we assessed survival, virus persistence, demyelination, and clinical disease. Mice lacking expression of endogenous class I and class II molecules (beta(2)m(o) Abeta(o) mice) died 3 to 4 weeks postinfection (p.i.) due to overwhelming virus replication in neurons. beta(2)m(o) Abeta(o) DQ6 and beta(2)m(o) Abeta(o) DQ8 mice had increased survival and decreased gray matter disease and virus replication compared to nontransgenic littermate controls. Both beta(2)m(o) Abeta(o) DQ6 and beta(2)m(o) Abeta(o) DQ8 mice developed chronic virus persistence in glial cells of the white matter of the spinal cord, with greater numbers of virus antigen-positive cells in beta(2)m(o) Abeta(o) DQ8 than in beta(2)m(o) Abeta(o) DQ6 mice. At day 45 p.i., the demyelinating lesions in the spinal cord of beta(2)m(o) Abeta(o) DQ8 were larger than those in the beta(2)m(o) Abeta(o) DQ6 mice. Earlier and more profound neurologic deficits were observed in beta(2)m(o) Abeta (o) DQ8 mice compared to beta(2)m(o) Abeta(o) DQ6 mice, although by 120 days p.i. both strains of mice showed similar extent of demyelination and neurologic deficits. Delayed-type hypersensitivity and antibody responses to TMEV demonstrated that the mice mounted class II-mediated cellular and humoral immune responses. The results are consistent with the hypothesis that rates of progression of demyelination and neurologic deficits are related to the differential ability of DQ6 and DQ8 transgenes to modulate the immune response and control virus.
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Affiliation(s)
- K D Pavelko
- Department of Immunology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, 55905, USA
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Breen M, Thomas R, Binns MM, Carter NP, Langford CF. Reciprocal chromosome painting reveals detailed regions of conserved synteny between the karyotypes of the domestic dog (Canis familiaris) and human. Genomics 1999; 61:145-55. [PMID: 10534400 DOI: 10.1006/geno.1999.5947] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The domestic dog is increasingly being recognized as a useful model for human disease. The aim of this study was to conduct the first detailed whole-genome comparison of human and dog using bidirectional heterologous chromosome painting (reciprocal Zoo-FISH) analysis. We used whole-chromosome paint probes produced from degenerate oligonucleotide-primed PCR amplification of high-resolution bivariate flow-sorted human and dog chromosomes. No fewer than 68 evolutionarily conserved segments were identified between the dog and the human karyotypes. The use of elongated metaphase chromosomes for both species allowed the boundaries of each evolutionarily conserved segment to be determined to subband resolution. The distribution of conserved segments is discussed, as are the applications of these data in refining the current status of the dog genome map.
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Affiliation(s)
- M Breen
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, United Kingdom.
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42
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Chemelli RM, Willie JT, Sinton CM, Elmquist JK, Scammell T, Lee C, Richardson JA, Williams SC, Xiong Y, Kisanuki Y, Fitch TE, Nakazato M, Hammer RE, Saper CB, Yanagisawa M. Narcolepsy in orexin knockout mice: molecular genetics of sleep regulation. Cell 1999; 98:437-51. [PMID: 10481909 DOI: 10.1016/s0092-8674(00)81973-x] [Citation(s) in RCA: 2111] [Impact Index Per Article: 84.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Neurons containing the neuropeptide orexin (hypocretin) are located exclusively in the lateral hypothalamus and send axons to numerous regions throughout the central nervous system, including the major nuclei implicated in sleep regulation. Here, we report that, by behavioral and electroencephalographic criteria, orexin knockout mice exhibit a phenotype strikingly similar to human narcolepsy patients, as well as canarc-1 mutant dogs, the only known monogenic model of narcolepsy. Moreover, modafinil, an anti-narcoleptic drug with ill-defined mechanisms of action, activates orexin-containing neurons. We propose that orexin regulates sleep/wakefulness states, and that orexin knockout mice are a model of human narcolepsy, a disorder characterized primarily by rapid eye movement (REM) sleep dysregulation.
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Affiliation(s)
- R M Chemelli
- Howard Hughes Medical Institute, Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, 75235-9050, USA
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Li R, Mignot E, Faraco J, Kadotani H, Cantanese J, Zhao B, Lin X, Hinton L, Ostrander EA, Patterson DF, de Jong PJ. Construction and characterization of an eightfold redundant dog genomic bacterial artificial chromosome library. Genomics 1999; 58:9-17. [PMID: 10331940 DOI: 10.1006/geno.1999.5772] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A large insert canine genomic bacterial artificial chromosome (BAC) library was built from a Doberman pinscher. Approximately 166,000 clones were gridded on nine high-density hybridization filters. Insert analysis of randomly selected clones indicated a mean insert size of 155 kb and predicted 8.1 coverage of the canine genome. Two percent of the clones were nonrecombinant. Chromosomal fluorescence in situ hybridization studies of 60 BAC clones indicated no chimerism. The library was hybridized with dog PCR products representing eight genes (ADA, TNFA, GCA, MYB, HOXA, GUSB, THY1, and TOP1). The resulting positive clones were characterized and shown to be compatible with an eightfold redundant library.
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Affiliation(s)
- R Li
- Stanford Center For Narcolepsy Research, 1201 Welch Road, Room P-112, Stanford, California 94305-5485, USA
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