Sjogren's syndrome: a neurological perspective / Síndrome de Sjogren: uma perspectiva neurológica

Abstract Sjogren's syndrome (SS) is a complex autoimmune disease characterized by lymphocytic infiltration of salivary and lacrimal glands, resulting in sicca symptoms. Additionally, SS presents with neurological manifestations that significantly impact the nervous system. This review aims to provide a comprehensive overview of the neurological aspects of SSj, covering both the peripheral and central nervous system involvement, while emphasizing diagnosis, treatment, and prognosis.

Resumo A síndrome de Sjogren (SS) é uma doença autoimune complexa caracterizada pela infiltração linfocítica das glândulas salivares e lacrimais, resultando em sintomas sicca. Além disso, a SS apresenta manifestações neurológicas que afetam significativamente o sistema nervoso. Esta revisão tem como objetivo fornecer uma visão abrangente dos aspectos neurológicos da SSj, abordando tanto o envolvimento do sistema nervoso periférico quanto do central, com ênfase no diagnóstico, tratamento e prognóstico.

Reshaping neuroimmunology: diagnosis and treatment in the era of precision medicine / Remodelando a neuroimunologia: diagnóstico e tratamento na era da medicina de precisão

Abstract Precision medicine has revolutionized the field of neuroimmunology, with innovative approaches that characterize diseases based on their biology, deeper understanding of the factors leading to heterogeneity within the same disease, development of targeted therapies, and strategies to tailor therapies to each patient. This review explores the impact of precision medicine on various neuroimmunological conditions, including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), optic neuritis, autoimmune encephalitis, and immune-mediated neuropathies. We discuss advances in disease subtyping, recognition of novel entities, promising biomarkers, and the development of more selective monoclonal antibodies and cutting-edge synthetic cell-based immunotherapies in neuroimmunological disorders. In addition, we analyze the challenges related to affordability and equity in the implementation of these emerging technologies, especially in situations with limited resources.

Resumo A medicina de precisão está revolucionando o campo da neuroimunologia, com uma abordagem inovadora caracterizada pela classificação de doenças com base em sua biologia, compreensão mais profunda dos fatores que levam à heterogeneidade dentro da mesma doença, desenvolvimento de terapias com alvos específicos e estratégias para adaptar as terapias a cada paciente. Esta revisão explora o impacto da medicina de precisão em várias condições neuroimunológicas, incluindo esclerose múltipla (EM), distúrbio do espectro da neuromielite óptica (NMOSD), doença associada ao anticorpo anti-glicoproteína da mielina do oligodendrócito (MOGAD), neurites ópticas, encefalites autoimunes e neuropatias imunomediadas. Discutimos avanços na subclassificação de doenças, reconhecimento de novas entidades, biomarcadores promissores e desenvolvimento de anticorpos monoclonais mais seletivos e imunoterapias de ponta baseadas em células sintéticas para as condições acima. Além disso, analisamos os desafios relacionados com acessibilidade e equidade na implementação dessas tecnologias emergentes, especialmente em ambientes com recursos limitados.

Progressive encephalomyelitis with rigidity and myoclonus: a case report / 中华神经科杂志

Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a specific subtype of the stiff-person syndrome, which is rare and difficult to diagnose clinically. A case of PERM in a 66-year-old female with a fluctuating progressive course was reported in this article. She had increased facial muscle tone, pruritus and sensory hypersensitivity mainly in the head and neck, medullary involvement syndrome and bilateral lower limb rigidity as the main clinical manifestations, and a previous history of pulmonary malignancy, thymoma, typeⅠ diabetes and Hashimoto′s thyroiditis. The patient′s serum and cerebrospinal fluid were positive for anti-glutamic acid decarboxylase antibody. The electromyogram showed a large number of motor unit potentials in the trunk and proximal extremities in the quiet state, which were significantly enhanced during spastic episodes, consistent with the electromyographic manifestations of stiff-person syndrome. The final diagnosis was PERM, and immunotherapy including gamma globulin and hormone responded well. PERM is a rare neurological autoimmune disease with atypical early symptoms, which can be easily misdiagnosed, and it requires attention to avoid delaying the diagnosis.

Advances in research of neonatal Fc receptor inhibitors in the treatment of autoimmune disease of the nervous system / 中华神经科杂志

Autoimmune diseases of the nervous system are a group of diseases caused by the body′s immune system attacking its own nervous system, resulting in structural damage and functional impairment of the corresponding tissues. Interventional clearance of pathogenic auto-antibodies has been shown to be effective in reducing immune damage, inhibiting disease progression and improving prognosis through extensive basic research and long-term clinical practice. The neonatal Fc receptor (FcRn)-mediated circulating protection mechanism of IgG contributes to the long half-life and high plasma levels of IgG. FcRn inhibitors are able to target and block the binding of FcRn to IgG, accelerating IgG clearance and reducing IgG levels. Therefore, the use of FcRn inhibitors in the treatment of autoimmune diseases of the nervous system could theoretically help to accelerate the clearance of pathogenic IgG, achieve good clinical efficacy and have promising applications. Research in this area has made considerable progress in recent years and this article will review this.

Tolerogenic dendritic cells involve in reconstructing T cell balance in neuroimmune conditions / 中华神经科杂志

Dendritic cells are the most powerful antigen-presenting cells in the human body, which are involved in the occurrence and development of multiple sclerosis, neuromyelitis optica, myasthenia gravis and other neuroimmune conditions. Recently, tolerogenic dendritic cells (tolDCs) are gradually becoming the research focus and therapeutic target of neuroimmune conditions. They can reconstruct the balance of T cells by inducing effector T cell anergy/deletion, and producing antigen-specific regulatory T cells, ultimately achieving the goal of maintaining immune tolerance. In this review, the mechanisms that tolDCs reconstruct T cell balance in neuroimmune conditions are analyzed and the research progress related to tolDC therapy is summarized.

Concurrencia entre el síndrome de Guillain-Barré y púrpura trombocitopénica inmune posiblemente inducidos por COVID-19 prolongado / Concurrence between Guillain-Barré syndrome and immune thrombocytopenic purpura possibly induced by long COVID-19

RESUMEN Durante la infección aguda por el SARVS-CoV-2 se produce una desregulación del sistema inmune que puede durar hasta ocho meses después de controlado el cuadro agudo. Esto, sumado a otros factores, posiblemente este asociado con un aumento del riesgo de aparición y concurrencia de enfermedades autoinmunes. La aparición simultanea del síndrome de Guillain-Barré (SGB) y púrpura trombocitopénica (PTI) se ha reportado poco en la literatura, y el SGB raramente se asocia con otra enfermedad autoinmune. Presentamos el caso de un varón que luego de un mes de tener un cuadro agudo de COVID-19 moderado, presentó concurrentemente SGB y PTI con respuesta adecuada al tratamiento.

ABSTRACT During acute SARS-CoV-2 infection, there is persistent deregulation of the immune system that can last up to 8 months after the acute condition is controlled. This, added to other factors, is possibly associated with an increased risk of the appearance and concurrence of autoimmune diseases. The simultaneous occurrence of GBS and ITP has been rarely reported in the literature, and GBS is rarely associated with another autoimmune disease. We present the case of a man who, one month after his recovery from acute moderate COVID-19, presented concurrent GBS and ITP with an adequate response to treatment.

Anti-neurexin-3α antibody-associated encephalitis with parkinsonism as the main manifestation: a case report / 中华神经科杂志

Anti-neurexin-3α antibody-associated encephalitis is rare in clinical practice. It often has a history of pre-infection. It is characterized by abnormal mental behavior, seizures, decreased consciousness, cognitive and sleep disorders, movement disorder, central hypoventilation and autonomic nervous dysfunction. Among them, dyskinesias are mainly involuntary movements of the mouth, face and limbs, dystonia, myoclonic seizures and other manifestations of increased movement. Parkinson′s symptoms manifested as decreased movement are rarely reported. A encephalitis patient with positive anti-neurexin-3α antibody is reported, who is a young female, mainly with parkinsonism such as slow movement, unsteady walking, difficulty in starting and turning around, and inability to hold things in both upper limbs, accompanied by abnormal mental behavior and cognitive dysfunction. After treatment with methylprednisolone and intravenous immunoglobulin, the prognosis is good.

Coexisting anti-N-methyl-D-aspartate receptor and anti-glutamic decarboxylase antibody- associated encephalitis after herpes simplex virus encephalitis: a case report / 中华神经科杂志

Herpes simplex virus encephalitis (HSE) is a common form of viral encephalitis, often with a single-phase course. A case of HSE with abnormal mental behavior as the main manifestation, admitted in Peking University Shenzhen Hospital in Octorber 2020, which improved after sufficient antiviral treatment was reported. After 2 months, abnormal mental behavior with memory deterioration recurred. It was considered as anti-N-methyl-D-aspartate receptor antibody combined with anti-glutamic decarboxylase antibody double-positive encephalitis, and improved after rituximab treatment. At present, there is no clinical report of such double antibody positive autoimmune encephalitis secondary to HSE. The purpose of this case report is to raise clinician awareness of post-HSE autoimmune encephalitis.

Precise diagnosis and treatment of pediatric central nervous system immune-related disease under molecular era / 中国医师杂志

Pediatric central nervous system (CNS) immune-related disease is a group of heterogeneous inflammatory conditions mainly affecting CNS. They usually happen in previously healthy individual, with varied clinical manifestations, pathophysiology and genetic changes. Patients require different therapy as well as have different prognosis. Immunotherapy often is helpful to control the disease. With the development of molecular techniques within the recent 10 years, the clinical spectrum and pathogenesis of these neuroinflammatory diseases is being recognized. Further investigations into these diseases are helpful for early diagnosis and targeted immunotherapy, contribute to decrease the mortality and morbidity, then improve the clinical outcome eventually. This study mainly discuss the neuroinflammatory diseases primarily happen in CNS.

Psicosis y alteraciones en la sensopercepción como manifestaciones atípicas de la poliangitis microscópica / Psychosis and alterations in sensory perception as atypical manifestations of microscopic polyangiitis

RESUMEN La poliangitis microscópica es una vasculitis sistémica, asociada a la positividad de anticuerpos anticitoplasma de neutrófilos, caracterizada por el compromiso necrosante de los vasos de pequeño calibre. Las manifestaciones clínicas de la poliangitis microscópica son variadas y las formas más severas se manifiestan con glomerulonefritis rápidamente progresiva y capilaritis pulmonar. El compromiso nervioso afecta principalmente el sistema periférico. La afectación a nivel central no es común, y hallazgos clínicos de psicosis y alteración del comportamiento son bastante infrecuentes en el contexto de estas enfermedades autoinmunes.

A B S T R A C T Microscopic polyangiitis is a systemic anti-neutrophil cytoplasmic antibody-associated vasculitis, and is associated with the necrotising small calibre vessels. Its clinical manifestations are varied, and the most severe forms manifest with rapidly progressive glomerulonephritis and pulmonary capillaritis. In the nervous system, it mainly involves the peripheral system. Involvement of the central nervous system is not common, and clinical findings of psychosis and behaviour alterations are infrequent.

Correctly understanding the relationship between autoimmune epilepsy and autoimmune encephalitis / 中华神经科杂志

Both autoimmune epilepsy and autoimmune encephalitis are new clinical concepts proposed in recent years with the development of neuroimmunology.Is it appropriate for the patients with new-onset epileptic seizures and positive neuron antibodies diagnosed as autoimmune encephalitis or autoimmune epilepsy? There are still disputes and misunderstandings.Because there are usually some common anti-neuronal antibodies detected in the serum or cerebrospinal fluid of them both,and additionally their clinical manifestations have certain overlaps,such as drug resistant epilepsy and cognitive impairment,both concepts are often confused in clinical practice,resulting in unnecessary excessive long-term anti-epileptic treatment.This review interprets the differences and connections between the two diseases on concepts,epidemiology,pathogenesis and related risk factors,clinical manifestations,auxiliary examination,treatment and prognosis.

Correctly understanding the relationship between autoimmune epilepsy and autoimmune encephalitis / 中华神经科杂志

Both autoimmune epilepsy and autoimmune encephalitis are new clinical concepts proposed in recent years with the development of neuroimmunology. Is it appropriate for the patients with new-onset epileptic seizures and positive neuron antibodies diagnosed as autoimmune encephalitis or autoimmune epilepsy? There are still disputes and misunderstandings. Because there are usually some common anti-neuronal antibodies detected in the serum or cerebrospinal fluid of them both, and additionally their clinical manifestations have certain overlaps, such as drug resistant epilepsy and cognitive impairment, both concepts are often confused in clinical practice, resulting in unnecessary excessive long-term anti-epileptic treatment. This review interprets the differences and connections between the two diseases on concepts, epidemiology, pathogenesis and related risk factors, clinical manifestations, auxiliary examination, treatment and prognosis.

Epstein-Barr virus infection as a predisposing factor for multiple sclerosis. An update from molecular biology, immunology and epidemiology / Infección por virus de Epstein-Barr como factor predisponente en la esclerosis múltiple. Actualización desde la biología molecular, la inmunología y la epidemiología

Abstract Introduction: Epstein-Barr virus is an infectious agent used to immortalize and induce polyclonal activation of B cells. It has been widely described that this virus produces changes in the cells it infects and in the immune response, and stimulates the development of autoimmune diseases. Objective: To characterize the association between Epstein-Barr virus and multiple sclerosis described in current scientific literature. Materials and methods: A 59-years range literature search was conducted in the PubMed, ScienceDirect, Redalyc and SciELO databases using the following MeSH terms: "Epstein-Barr virus, multiple sclerosis autoimmune diseases, autoimmune diseases of the nervous system". Results: Many studies describe the association between Epstein-Barr virus and multiple sclerosis. It is believed that acute infection and viral reactivation promote the development of multiple sclerosis. Conclusions: It is necessary to conduct further research on the pathogenesis and morphophysiological and neuroimmunological changes -at the ecological, molecular, cellular, tissue, organic and systemic level- induced by the immune response and that favor the development of multiple sclerosis.

Resumen Introducción. El virus de Epstein-Barr (VEB) es un agente inmortalizador y activador policlonal de células B. Es conocido que este virus induce cambios en las células que infecta y en la respuesta inmune, y que favorece la presentación de enfermedades autoinmunes. Objetivo. Caracterizar la asociación entre el VEB y la esclerosis múltiple (EM) descrita en la literatura actual. Materiales y métodos. Se realizó una búsqueda bibliográfica con rango de 59 años mediante los términos DeCS "virus de Epstein-Barr, esclerosis múltiple, enfermedades autoinmunes del sistema nervioso" en las bases de datos PubMed, ScienceDirect, Redalyc y SciELO. Resultados. Hay muchos estudios que describen la asociación del VEB con la EM. Se cree que la infección aguda y la reactivación viral contribuyen al desarrollo de la enfermedad. Conclusiones. Es necesario realizar más estudios que indaguen sobre la patogénesis, los cambios morfofisiológicos y las alteraciones neuroinmunológicas en la ecología molecular, celular, tisular, orgánica y sistémica inducida por la respuesta inmune y que favorecen el desarrollo de la EM.

Autoantibody screening for the diagnosis of autoimmune cerebellitis / 中华神经科杂志

Objective To establish a test of autoantibody-panel for the diagnosis of autoimmune cerebellitis (AC) and determine the prevalence of AC in patients with cerebellar ataxia of unknown etiology.Methods Autoantibody screening tests with indirect immunofluorescence were performed in serum and cerebrospinal fluid (CSF) samples of 400 previously'idiopathic'Chinese patients with cerebral ataxia (inpatients and outpatients in Peking Union Medical College Hospital or referred from hospitals of Beijing Encephalitis Group from 2016 to 2018).Immunotherapy was given to autoantibody positive patients and the effectiveness of immunotherapy was assessed.Detailed AC autoantibodies panel included anti-glutamate decarboxylase 65 (GAD65) antibody,anti-Tr (delta notch-like epidermal growth factor-related receptor (DNER)) antibody,anti-zinc finger protein 4 (ZIC4) antibody,anti-inositol 1,4,5-trisphosphate receptor 1 (ITPR1) antibody,anti-homer protein homolog 3 (Homer 3) antibody,anti-neurochondrin (NCDN) antibody,anti-carbonic anhydrase-related protein (CARP) antibody and anti-Purkinje cell antibody 2 (PCA2) antibody.Results Eight out of 400 (2％) ataxia patients were positive for this AC panel tests,of whom two were positive for anti-GAD65 antibody,two for anti-Tr antibody,one for anti-PCA2 antibody,one for anti-Homer 3 antibody and two were positive for serum anti-NCDN antibody.Autoantibodies against ZIC4,ITPR1 and CARP were not detected in this cohort.Two of the eight ataxia patients also presented with limbic encephalitis,and only one anti-GAD antibody patient was screened with underlying small cell lung carcinoma (SCLC).All the eight patients received immunotherapy and four experienced partial response.Conclusions Autoimmune cerebellitis is the cause of acquired cerebellar ataxia.Tests of autoantibodies associated with AC have diagnostic value for paraneoplastic and non-paraneoplastic cerebellar ataxia.Immunotherapy may yield partial response in patients with AC.

Antibody-related central nervous system autoimmune diseases: exploration and challenge / 中华神经科杂志

Antibody-related central nervous system (CNS) autoimmune diseases are a frontier of neuroimmunology.CNS viral infections including herpes simplex encephalitis and Japanese encephalitis can induce anti-N-methyl-D-aspartic acid receptor encephalitis with a double-peak presentation.Pathogenic antibody is the specific diagnostic biomarker which renders the establishment of new autoimmune entities.However,the pathogenicity and clinical relevance of some new antibodies need further evaluation.The challenge from cases with overlapping antibodies or antibody-negative limbic encephalitis can be solved with the reference to the diagnostic criteria and recommendation.

Guillain, Barraquer and I / Guillain, Barraquer e eu

ABSTRACT The year 2016 was the centennial anniversary of the recognition of the Guillain-Barré syndrome, which was first described by George Guillain, Jean-Alexandre Barré and André Strohl. In celebration of the centennial, this historical review describes aspects of the contributions of Guillain and the Spanish neurologist, Barraquer-Bordas and a brief account of the Fourth International Neurological Congress, which brought together Guillain and Barraquer-Bordas. There were many outstanding Brazilian physicians at that meeting. Finally, the author describes his interaction with Barraquer-Bordas and provides an account of his influence in shaping a generation of Brazilian neurologists, including himself.

RESUMO O ano de 2016 foi o aniversário do centenário do reconhecimento da síndrome de Guillain-Barré (GBS), que foi descrita pela primeira vez por George Guillain, Jean-Alexandre Barré e André Strohl. Em comemoração ao centenário, esta revisão histórica descreve aspectos das contribuições de Guillain e Barraquer-Bordas e uma breve descrição do IV Congresso Neurológico Internacional, que reuniu Guillain e o neurologista espanhol Barraquer-Bordas. Naquela reunião houve participação também de excelentes médicos brasileiros. Finalmente, o autor descreve sua interação com Barraquer-Bordas e fornece uma descrição de sua influência na formação de uma geração de neurologistas brasileiros, incluindo ele próprio.

Clinical characteristics of 12 patients with anti-leucine rich glioma inactivated protein 1 encephalitis / 中华神经科杂志

Objective To analyze the clinical features and prognosis of anti-leucine rich glioma inactivated protein 1 (LGI1) encephalitis.Methods Twelve encephalitis patients with anti-LGI1 antibodies were collected from the First Affiliated Hospital of Zhengzhou University from June 2015 to December 2016.The clinical manifestations,electroencephalogram,laboratory examination and imaging findings were summarized and the prognosis was observed.The modified Rankin Scale (mRS) was used for evaluation before and after treatment.Results The major clinical features included memory deficit (10/12),spatial disorientation (7/12),epilepsy with generalized tonic-clonic seizures (9/12),faciobrachial dystonic seizures (7/12),hyponatremia (5/12),mental and behavioral abnormalites (1/12),light sleep (1/12),increased sleep (3/12),aphasis (4/12),dysphagia,choking (2/12),headache (1/12),dizziness (2/12),fatigue (2/12),ataxia (2/12),bradycardia (3/12),urinary disorders (2/12),intestinal obstruction (1/12),diarrhea (1/12).Admission mRS score was found to be three in eight cases,four in four cases.The abnormal electroencephalogram was found in six cases,mainly manifested as focal or diffuse slow wave,some accompanied by epileptic wave.MRI scan of brain showed abnormal signals in four cases,mainly involved medial temporal lobe,hippocampus,basal ganglia,while one patient avoided MRI scan due to implantation of pacemaker.Two patients presented with pulmonary nodules,one case with positive thyroid antibody and increased rheumatoid factor.The follow-up after treatment showed no one died;mRS score was two in two cases,one in nine cases and zero in one case;the sequelae were memory deficit,increased sleep,faciobrachial dystonic seizures.Conclusions Anti-LGI1 encephalitis is a treatable disease,cardinal clinical features of which are seizures,cognitive disorders,hyponatremia.Immunotherapy can improve the symptoms of the disease significantly,and the prognosis is better comparatively.

Research progress and current status of neurosystemic autoimmunity diseases / 中华检验医学杂志

The clinical manifestations of neurosystemic autoimmunity diseases are complicated and varied. Symptoms of different diseases often overlap and are not easily identified. It is very important to detect autoantibodies in serum and(or) cerebrospinal fluid for diagnosis, differential diagnosis, treatment and prediction of disease. With advances in autoantibody detection, multi-method and multi-index joint detection strategies, the results of which can provide more comprehensive disease information than single indicator detection and make diagnosis and treatment of disease more quickly and accurately, are widely used. Over the past decade, a series of pathogenic autoantibodies were identified. The discovery of these autoantibodies led to the diagnosis of many previously undiagnosed diseases. This paper reviews the research progress of autoantibodies associated with neurosystemic autoimmunity diseases, analyzes the current situation of detection in China and puts forward some suggestions in order to provide guidance for basic research and clinical work.

Miastenia gravis seronegativa: revisión de la literatura / Seronegative Myasthenia Gravis: A Literature Review

RESUMEN En 1976 se identificaron varios anticuerpos dirigidos contra el receptor de acetil colina en el suero de los pacientes con miastenia gravis (MG). Sin embargo, luego de unos años, se evidenció que aproximadamente el 20 % de los pacientes con MG generalizada y con evidencia electrofisiológica de un trastorno de la unión neuromuscular, no expresan dichos anticuerpos por radioinmunoensayo (RIA); éstos constituyen los casos de miastenia gravis seronegativa (MGSN). El diagnóstico en estos pacientes es difícil, dada la ausencia de autoanticuerpos detectables en suero y la falta de estudios neurofisiológicos sensibles. Recientemente un nuevo método basado en ensayos celulares muestra un aumento significativo en la detección de miastenia seropositiva, en casos diagnosticados previamente como seronegativos. Este artículo pretende dar un abordaje sobre la fisiopatología de la miastenia gravis seronegativa, así como una actualización de los últimos avances sobre su diagnóstico. También busca hacer una revisión sobre el contexto general actual de esta patología en Colombia.

SUMMARY In 1976 antibodies against acetyl-choline receptor were identified on the serum of patients with myasthenia gravis. However, some years later, it became clear that about 20% of patients with generalized MG and an electro physiologic disorder on the neuromuscular junction did not express these antibodies by radioimmunoassay (RIPA). These cases represent seronegative myasthenia gravis (SNMG). The diagnosis of these patients is difficult, given the absence of detectable autoantibodies on serum and the lack of sensitive neurophysiologic tests. Recently, a new method based on cellular assays shows an increase on detection of seropositive MG from cases, which were initially diagnosed as seronegative. This article reviews the physiopathology of seronegative MG and gives an update on the latest advances concerning its diagnosis. It also hopes to approach the current general context of the illness in Colombia.

Corticosteroid Treatment in Autoimmune Encephalitis

An increasing number of neuronal autoantibodies which target cell surface or synaptic proteins have been discovered over the last decade. Autoimmune encephalitis refers to this new category of autoimmune-mediated neurological disorders, which involve the central nervous system. Recent studies have established that autoimmune encephalitis is now the major cause of encephalitis, which was previously considered to be encephalitis of an unknown etiology. Moreover, the fact that autoimmune encephalitis is potentially treatable with immunomodulating therapy has changed the paradigm for the diagnosis and treatment of acute encephalitis syndrome. We herein review the pathophysiology, clinical manifestations, diagnosis, and treatment of autoimmune encephalitis with a focus on corticosteroid therapy as the first-line immunotherapy. In addition, regarding the diagnostic approach, we emphasize the differentiation between autoimmune and infectious encephalitis, because this distinction is not necessarily clear-cut in real clinical practice and should be considered when determining the initiation and type of immunotherapy.