RESUMO
There are two different prion conformations: (1) the cellular natural (PrPC) and (2) the scrapie (PrPSc), an infectious form that tends to aggregate under specific conditions. PrPC and PrPSc are widely different regarding secondary and tertiary structures. PrPSc contains more and longer ß-strands compared to PrPC. The lack of solved PrPSc structures precludes a proper understanding of the mechanisms related to the transition between cellular and scrapie forms, as well as the aggregation process. In order to investigate the conformational transition between PrPC and PrPSc, we applied MDeNM (molecular dynamics with excited normal modes), an enhanced sampling simulation technique that has been recently developed to probe large structural changes. These simulations yielded new structural rearrangements of the cellular prion that would have been difficult to obtain with standard MD simulations. We observed an increase in ß-sheet formation under low pH (≤ 4) and upon oligomerization, whose relevance was discussed on the basis of the energy landscape theory for protein folding. The characterization of intermediate structures corresponding to transition states allowed us to propose a conversion model from the cellular to the scrapie prion, which possibly ignites the fibril formation. This model can assist the design of new drugs to prevent neurological disorders related to the prion aggregation mechanism.
Assuntos
Simulação de Dinâmica Molecular , Proteínas PrPC/química , Proteínas PrPSc/química , Agregados Proteicos , Humanos , Concentração de Íons de Hidrogênio , Conformação Proteica em Folha beta , Dobramento de ProteínaRESUMO
Scrapie is a fatal and progressive transmissible spongiform encephalopathy (TSE) of natural occurrence in sheep and goats. The suspicion of scrapie may be based on clinical signs; however, the detection of pathological features of the prionic protein (PrP) in target tissues is necessary to diagnose the disease. The presence of an abnormal protein form (PrPSc) in lymphoreticular and nervous tissues is an important characteristic in diagnosis. This paper reports a case of scrapie in a flock of 55 Suffolk crossbred sheep, 19 Santa Inês sheep and 21 goats in the Mato Grosso state, midwestern Brazil. The animals were euthanized after the confirmation of a scrapie case with clinical signs in a Suffolk sheep in the same farm...
Scrapie é uma encefalopatia espongiforme transmissível (EET) progressiva e fatal de ocorrência natural em ovinos e caprinos. A suspeita de scrapie é baseada nos sinais clínicos, porém a manifestação patológica da proteína priônica (PrP) nos tecidos-alvo é necessária para a confirmação da doença. A presença de uma forma anormal da proteína (PrPSc) em tecido linforreticular e tecido nervoso constitui uma característica importante para o diagnóstico. Este trabalho é o relato de um foco de scrapie ocorrido em rebanho com 55 ovinos mistos Suffolk, 21 caprinos e 19 ovinos Santa Inês, na região Centro-Oeste do Brasil. Os animais foram eutanasiados após a confirmação de um caso de scrapie com sinais clínicos em um ovino Suffolk nessa propriedade...
Assuntos
Animais , Ovinos/virologia , Príons/isolamento & purificação , Proteínas PrPSc/análise , Ruminantes , Scrapie/virologia , Tecido Linfoide/patologia , Imuno-Histoquímica/veterinária , Técnicas Histológicas/veterináriaRESUMO
Scrapie is a fatal and progressive transmissible spongiform encephalopathy (TSE) of natural occurrence in sheep and goats. The suspicion of scrapie may be based on clinical signs; however, the detection of pathological features of the prionic protein (PrP) in target tissues is necessary to diagnose the disease. The presence of an abnormal protein form (PrPSc) in lymphoreticular and nervous tissues is an important characteristic in diagnosis. This paper reports a case of scrapie in a flock of 55 Suffolk crossbred sheep, 19 Santa Inês sheep and 21 goats in the Mato Grosso state, midwestern Brazil. The animals were euthanized after the confirmation of a scrapie case with clinical signs in a Suffolk sheep in the same farm. Samples of brainstem at the level of the obex and lymphoid issues like palatine tonsils, mesenteric lymph nodes, third eyelid fixed in formalin 10% were processed for histological examination. Histological examination with hematoxylin and eosin did not show any microscopic changes in samples. Immunohistochemistry (IHC) examination to detect anti-prion PrPSc was performed in lymphoid tissues. Scrapie diagnosis was confirmed based on IHC positive results for PrPSc in lymphoid tissues of a crossbreed goat and four Santa Inês sheep, without any clinical scrapie signs. IHC showed positive staining in at least three lymphoid germinal centers in goat mesenteric lymph node, palatine tonsil, and third eyelid samples. The mesenteric lymph node, and tonsil samples of all sheep showed positive immunostaining, and only one sheep showed positive staining in lymphoid follicles in the third eyelid. Scrapie diagnosis using IHC in fixed samples of lymphoreticular tissue is technically feasible to detect the disease in both goats and sheep, as a form of pre-clinical diagnosis. The results indicate that the herd was infected by a sheep coming from another herd where scrapie had been diagnosed before(AU)
Scrapie é uma encefalopatia espongiforme transmissível (EET) progressiva e fatal de ocorrência natural em ovinos e caprinos. A suspeita de scrapie é baseada nos sinais clínicos, porém a manifestação patológica da proteína priônica (PrP) nos tecidos-alvo é necessária para a confirmação da doença. A presença de uma forma anormal da proteína (PrPSc) em tecido linforreticular e tecido nervoso constitui uma característica importante para o diagnóstico. Este trabalho é o relato de um foco de scrapie ocorrido em rebanho com 55 ovinos mistos Suffolk, 21 caprinos e 19 ovinos Santa Inês, na região Centro-Oeste do Brasil. Os animais foram eutanasiados após a confirmação de um caso de scrapie com sinais clínicos em um ovino Suffolk nessa propriedade. Amostras de tronco cerebral na altura do obex e tecidos linfoides, que incluíram tonsilas, linfonodos mesentéricos e tecido linfoide da terceira pálpebra foram processados para exame histológico. O exame histológico utilizando a coloração de hematoxilina e eosina não revelou a presença de alterações microscópicas nos tecidos examinados. O diagnóstico de scrapie foi confirmado com base nos resultados positivos de imuno-histoquímica (IHQ) para PrPSc nos tecidos linfoides de um caprino sem raça definida e quatro ovinos da raça Santa Inês, sem sinais clínicos de scrapie. A IHQ apresentou marcação positiva em pelo menos três centros linfoides na tonsila, terceira pálpebra e linfonodo mesentérico do caprino. Em todos os ovinos, a IHQ revelou marcação positiva nos folículos linfoides da tonsila palatínica e linfonodo mesentérico; a marcação positiva nos folículos linfoides da terceira pálpebra só foi observada em um dos ovinos. Este trabalho demonstra a importância da utilização de tecido linforreticular para o diagnóstico pré-clínico de scrapie através de IHQ e é tecnicamente viável em ovinos e caprinos. [...](AU)
Assuntos
Animais , Scrapie/virologia , Ruminantes/virologia , Ovinos/virologia , Príons/isolamento & purificação , Tecido Linfoide/patologia , Proteínas PrPSc/análise , Imuno-Histoquímica/veterinária , Técnicas Histológicas/veterináriaRESUMO
The diagnosis of Creutzfeldt-Jakob disease (CJD) is often a challenge for most physicians given its extremely low incidence and different clinico-pathological presentations. We report the case of a 56-year old patient native to Puerto Rico suspected of sporadic Creutzfeldt-Jakob disease (sCD). The symptoms at onset were notorious for bilateral cortical blindness followed by rapidly progressive cognitive decline, visual deficit, increased levels of CSF 14-3-3 and tau along with positive brain MRI and EEG, are highly indicative of CJD. The definite diagnosis was confirmed by the National Prion Disease Pathology Surveillance Center (NPDPSC), in Cleveland, Ohio, USA. Lack of genetic mutations in the prion protein (PrP) gene, widespread histopathological changes and the accumulation of scrapie PrP (PrPSc) in the brain confirmed the diagnosis of sCJD. The patient, admitted to our institution in 2011, represents the first detailed report of sCJD in a native Puerto Rican patient living in Puerto Rico.
Assuntos
Encéfalo/fisiopatologia , Síndrome de Creutzfeldt-Jakob/diagnóstico , Proteínas PrPSc/metabolismo , Síndrome de Creutzfeldt-Jakob/genética , Síndrome de Creutzfeldt-Jakob/fisiopatologia , Eletroencefalografia , Feminino , Hispânico ou Latino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Príons/genética , Porto RicoRESUMO
Breast cancer is a major public health problem in Latin America (LA) and the most common form of cancer among women. An important variability according to ethnicity/race with respect to incidence/mortality, clinical characteristics, and prognosis is observed throughout LA. In addition, women are more likely to develop breast cancer (BC) at younger age and to be diagnosed at an advanced stage compared to western women. While little is known about specific risk factors, changes in reproductive pattern (parity, breastfeeding) and lifestyle factors including sedentary behaviours, unhealthy diet, and alcohol intake may contribute to the increase of BC incidence. In this paper we give an overview of the burden and patterns of BC, review the leading causes of BC and discuss the possible ways to improve BC prevention and control in LA.
El cáncer de mama (CaMa) es uno de los mayores problemas de salud pública en América Latina (AL) y el cáncer más frecuente en mujeres. Se observa una importante variabilidad en la incidencia/mortalidad, las características clínicas y el pronóstico según la etnia/raza a lo largo de AL. Además, las mujeres latinoamericanas son más propensas a desarrollar CaMa en edades más tempranas y a ser diagnosticadas en una etapa más avanzada, comparando con mujeres occidentales. Aunque poco se sabe sobre sus factores de riesgo específicos, cambios en los patrones reproductivos (paridad y lactancia) y estilos de vida, incluyendo los hábitos sedentarios, las dietas poco saludables y el consumo de alcohol, podrían contribuir al incremento de la incidencia del CaMa. En este artículo se da una visión general de la carga y los patrones del CaMa, se revisan las causas principales del CaMa y se discuten posibles vías para mejorar la prevención y el control del CaMa en AL.
Assuntos
Animais , Camundongos , Colagenases/química , Detergentes/química , Proteínas PrPSc/isolamento & purificação , Sarcosina/análogos & derivados , Scrapie/etiologia , Cloreto de Sódio/química , Cromatografia de Afinidade , Camundongos Endogâmicos ICR , Octoxinol/química , Sarcosina/química , BaçoRESUMO
La enfermedad de Creutzfeldt-Jakob (ECJ) es una enfermedad neurológica fatal producida por la isoforma patológica de la proteína priónica humana. Se reporta las características clínicas de seis casos de la forma esporádica de ECJ con diagnóstico definitivo por histopatología, y cinco casos con diagnóstico probable, en pacientes atendidos en el Instituto Nacional de Ciencias Neurológicas del Perú. La edad de inicio en los casos definitivos fue de 55,8 años y, en los probables, de 59,6 años, con predominio del sexo masculino. El tiempo de enfermedad fue de 8,8 meses. Se encontró un EEG típico en 50% de los casos definitivos y 80% de los probables. La proteína 14-3-3 en líquido cefalorraquídeo fue positiva en un caso probable y los hallazgos típicos en resonancia magnética se observaron en dos casos probables. Todos los casos cursaron con una evolución clínica típica de la enfermedad, y se considera el primer reporte de ECJ en el Perú. (AU)
Creutzfeldt-Jakob disease (CJD) is a fatal neurological disease caused by pathological isoform of the human prion protein. Clinical features of six cases of the sporadic form of CJD with definitive diagnosis by histopathology, and five cases with probable diagnosis were reported in patients treated at the Peruvian National Institute of Neurological Sciences. The average age of onset in definite cases was 55.8 years and in probable cases was 59.6, mostly males. The average disease duration was 8.8 months. A typical EEG was found in 50% of definite cases and in 80% of probable. The 14-3-3 protein in cerebrospinal fluid was positive in a probable case, and typical MRI findings were observed in two probable cases. All cases studied had a typical clinical course of the disease, and it is considered as the first report of CJD in Peru. (AU)
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Síndrome de Creutzfeldt-Jakob , Doenças Priônicas , Proteínas PrPSc , Príons , PeruRESUMO
BACKGROUND: Epidemiological data on Creutzfeldt-Jakob disease (CJD) from Latin America are limited. We present a comprehensive epidemiological survey on CJD patients in Argentina based on systematic surveillance between 1997 and 2008. METHODS: A CJD Surveillance Referral Center (SRC) was established in Argentina in 1997; previously a Neuropathology Referral Center was used from 1983 to 1996. All suspected cases referred to the SRC were classified using established criteria on the basis of information derived from the following: clinical data form, EEG, MRI (both for central review), cerebrospinal fluid (CSF) for protein 14-3-3 Western blot (WB), autopsy or biopsy material for neuropathology, prion protein (PrP) immunohistochemistry and PrP WB, as well as blood for DNA studies (when brain tissue was not available). RESULTS: Of the 517 patients referred to the SRC between 1997 and 2008, 211 (40.8%) had CJD or other transmissible spongiform encephalopathies (TSEs) (definite or probable). Possible cases totaled 14.5%, while cases with no WHO criteria accounted for 16.4%. Non-CJD cases excluded by biopsy/autopsy or during follow-up corresponded to 28.2% of the 517 referrals. Main differential diagnoses included neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, vascular, metabolic or viral encephalopathy, and Hashimoto's disease. Five percent of referred patients ultimately recovered. Eighty-three percent of TSE cases were sporadic CJD; 17% were genetic, mainly E200K (15.6%); the remaining 1.4% included an octarepeat insertion and two Gerstmann-Sträussler-Scheinker cases (P102L). Seventy-four of 100 definite cases had frozen tissue available for molecular subtyping (PrP(Sc)/codon 129). CSF protein 14-3-3 WB sensitivity was 72.3% and specificity was 92.1%. Clinical diagnostic criteria for probable CJD when compared to definite diagnosis by neuropathology showed 71.3% sensitivity, 86.2% specificity, 94.4% positive predictive value and 48% negative predictive value. Country incidence increased over time and reached 0.85 cases per million in 2008, with the highest rate detected in the city of Buenos Aires (1.8). Districts with 6% of the total population have never reported suspected cases. CONCLUSION: In spite of an increase in incidence observed over time, the difference between Buenos Aires city, where the incidence is comparable to that of smaller European countries with higher population density, and the incidence observed in the rest of the country suggests underreporting in nonmetropolitan areas, probably due to a lack of access to specialized medical facilities. CSF WB sensitivity results for protein 14-3-3 were probably linked to the fact that testing was not routinely repeated during the course of the disease, when earlier test results had been negative. The spectrum of molecular CJD subtypes observed did not differ from other countries in Europe. No iatrogenic or variant CJD cases were identified. The sensitivity and negative predictive value of clinical diagnostic criteria for probable CJD (which includes EEG and/or CSF protein 14-3-3 levels) may have been resulted from confirmed cases not meeting probable criteria before autopsy, due to a lack of ancillary tests such as EEG and/or CSF 14-3-3 WB, or because negative tests were not repeated during follow-up.
Assuntos
Síndrome de Creutzfeldt-Jakob/diagnóstico , Síndrome de Creutzfeldt-Jakob/epidemiologia , Vigilância da População/métodos , População Urbana/estatística & dados numéricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Argentina/epidemiologia , Autopsia , Biópsia , Western Blotting , Síndrome de Creutzfeldt-Jakob/genética , Diagnóstico Diferencial , Eletroencefalografia , Feminino , Humanos , Incidência , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Proteínas PrPSc , Sensibilidade e EspecificidadeRESUMO
Prion diseases are caused by an abnormal form of the prion protein (PrP(Sc)). We identified, with lectins, post-translational modifications of brain proteins due to glycosylation in a Gerstmann-Sträussler-Scheinker (GSS) patient. The lectin Amaranthus leucocarpus (ALL), specific for mucin type O-glycosylated structures (Galß1,3 GalNAcα1,0 Ser/Thr or GalNAcα1,0 Ser/Thr), and Sambucus nigra agglutinin (SNA), specific for Neu5Acα2,6 Gal/GalNAc, showed positive labeling in all the prion deposits and in the core of the PrP(Sc) deposits, respectively, indicating specific distribution of O-glycosylated and sialylated structures. Lectins from Maackia amurensis (MAA, Neu5Acα2,3), Macrobrachium rosenbergii (MrL, Neu5,9Ac2-specific) and Arachis hypogaea (PNA, Gal-specific) showed low staining of prion deposits. Immunohistochemistry colocalization with prion antibody indicated that all lectins stained prion protein deposits. These results show that specific modifications in the glycosylation pattern are closely related to the hallmark lesions and might be an early event in neuronal degeneration in GSS disease.
Assuntos
Doença de Gerstmann-Straussler-Scheinker/metabolismo , Polissacarídeos/metabolismo , Proteínas PrPSc/metabolismo , Doença de Gerstmann-Straussler-Scheinker/patologia , Humanos , Imuno-Histoquímica , Lectinas , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Processamento de Proteína Pós-TraducionalRESUMO
Transmissible spongiform encephalopathies are fatal neurodegenerative diseases caused by the conversion of prion protein (PrP(C)) into an infectious isoform (PrP(Sc)). How this event leads to pathology is not fully understood. Here we demonstrate that protein synthesis in neurons is enhanced via PrP(C) interaction with stress-inducible protein 1 (STI1). We also show that neuroprotection and neuritogenesis mediated by PrP(C)-STI1 engagement are dependent upon the increased protein synthesis mediated by PI3K-mTOR signaling. Strikingly, the translational stimulation mediated by PrP(C)-STI1 binding is corrupted in neuronal cell lines persistently infected with PrP(Sc), as well as in primary cultured hippocampal neurons acutely exposed to PrP(Sc). Consistent with this, high levels of eukaryotic translation initiation factor 2alpha (eIF2alpha) phosphorylation were found in PrP(Sc)-infected cells and in neurons acutely exposed to PrP(Sc). These data indicate that modulation of protein synthesis is critical for PrP(C)-STI1 neurotrophic functions, and point to the impairment of this process during PrP(Sc) infection as a possible contributor to neurodegeneration.
Assuntos
Proteínas de Choque Térmico/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Neurônios/metabolismo , Príons/metabolismo , Biossíntese de Proteínas , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Linhagem Celular , Citoproteção , Fator de Iniciação 2 em Eucariotos/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , Neuritos/enzimologia , Neurônios/citologia , Neurônios/enzimologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteínas PrPSc/metabolismo , Ligação Proteica , Serina-Treonina Quinases TOR , Regulação para CimaRESUMO
Since the first description of prion diseases, great effort has been made toward comprehending this new paradigm in biology. Despite large advances in the field, many questions remain unanswered, especially concerning the conversion of PrP(C) into PrP(Sc). How this conformational transition evolves is a crucial problem that must be solved in order to attain further progress in therapeutics and prevention. Recent developments have indicated the requirement for partners of the prion protein in triggering the conversion. In the present review, we will explore the interaction of PrP with some of its most intriguing partners, such as sulfated glycans and nucleic acids. These molecules seem to play a dual role in prion biology and could be fundamental to explaining how prion diseases arise, as well as in the development of effective therapeutic approaches.