Search results for "Fibril"

Nucleation mechanisms and morphologies in insulin amyloid fibril formation

2011

Urea Cycle Metabolites and Atrial Fibrillation or Heart Failure Risk: Two Case-Control Studies in the PREDIMED Trial

2021

OBJECTIVES: To prospectively analyze the associations between urea cycle metabolites and incident atrial fibrillation (AF) or heart failure (HF), and to evaluate the effect of a Mediterranean diet (MD) intervention on such associations. METHODS: We designed two nested case-control studies within the PREDIMED trial, a randomized controlled trial aimed to evaluate the effect of two MD interventions, supplemented with either extra virgin olive oil (EVOO) or nuts, on cardiovascular disease (CVD). Fasting blood samples were collected at baseline and urea cycle metabolites (arginine, citrulline, and ornithine) and methylarginines (asymmetric dimethylarginine/symmetric dimethylarginine ratio (ADMA…

Age-related accumulation of congophilic fibrillar inclusions in endocrine cells

1991

Intracellular fibrillar congophilic inclusions are well known as neurofibrillary tangles in neurons and as Biondi bodies in choroid plexus epithelial cells. Recently similar amyloid-like inclusions in adrenal cortical cells were described (Eriksson and Westermark 1990). This study on 150 adrenal glands confirms these observations. In our material the age-related accumulation of congophilic inclusions starts earlier (in the sixth decade) and reaches a higher incidence (42.7%). We found similar intracellular inclusions in other endocrine organs, for example in the anterior lobe of the pituitary, in the cells of parathyroid glands and in Sertoli cells. The age-related incidence of these fibril…

Pattern of brain destruction in Parkinson's and Alzheimer's diseases

1996

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common age-related degenerative disorders of the human brain. Both diseases involve multiple neuronal systems and are the consequences of cytoskeletal abnormalities which gradually develop in only a small number of neuronal types. In AD, susceptible neurons produce neurofibrillary tangles (NFTs) and neuropil threads (NTs), while in PD, they develop Lewy bodies (LBs) and Lewy neurites (LNs). The specific lesional pattern of both illnesses accrues slowly over time and remains remarkably consistent across cases. In AD, six developmental stages can be distinguished on account of the predictable manner in which the neurofibrillar…

Koronarogrāfija pacientiem ar agrīnu repolarizācijas sindromu

2016

Tēmas aktualitāte. Agrīna repolarizācija (AR) EKG ilgu laiku bija uzskatīts kā labdabīgs variants, jo rādījās parasti jauniešiem, sevišķi atlētiem. Bet pēdējā laikā pierādīts ka AR ir dažādas formas un ne visiem tas ir labdabīgs, bet tam ir bīstamas sekas, tādas ka ventrikulāra aritmija un pēkšņa kardiāla nāve. AR var būt tomēr arī gados veciem cilvēkiem un kam jau diagnosticēta arteriālā hipertensija, KSS utt. Darba mērķis. Atrast saistību starp pierādīto agrīnu repolarizāciju EKG un izmaiņām koronārajos asinsvados koronarogrāfijā. Materiāli un metodes. Pētījums ir retrospektīvs. Bija iesaistīti 150 pacienti, kuriem ir agrīna repolarizācija EKG un veikta koronarogrāfija. Pacienti bija sada…

Amyloid Fibrils Formation of Concanavalin A at Basic pH

2011

Mechanisms of partial unfolding and aggregation of proteins are of extreme interest in view of the fact that several human pathologies are characterized by the formation and deposition of protein-insoluble material, mainly composed of amyloid fibrils. Here we report on an experimental study on the heat-induced aggregation mechanisms, at basic pH, of concanavalin A (ConA), used as a model system. Thioflavin T (ThT) fluorescence and multiangle light scattering allowed us to detect different intertwined steps in the formation of ConA aggregates. In particular, the ThT fluorescence increase, observed in the first phase of aggregation, reveals the formation of intermolecular β-sheet structure wh…

Decoding vibrational states of Concanavalin A amyloid fibrils.

2015

International audience; Amyloid and amyloid-like fibrils are a general class of protein aggregates and represent a central topic in life sciences for their involvement in several neurodegenerative disorders and their unique mechanical and supramolecular morphological properties. Both their biological role and their physical properties, including their high mechanical stability and thermodynamic inertia, are related to the structural arrangement of proteins in the aggregates at molecular level. Significant variations may exist in the supramolecular organization of the commonly termed cross-β structure that constitutes the amyloid core. In this context, a fine knowledge of the structural deta…

The sea urchin embryo: a model to study Alzheimer's beta amyloid induced toxicity.

2009

Abstract Alzheimer’s disease (AD) is the most common form of dementia. The cause of AD is closely related to the accumulation of amyloid beta peptide in the neuritic plaques. The use of animal model systems represents a good strategy to elucidate the molecular mechanism behind the development of this pathology. Here we use the Paracentrotus lividus embryo to identify molecules and pathways that can be involved in the degenerative process. As a first step, we identified the presence of an antigen related to the human APP, called Pl APP. This antigen, after gastrula stage, is processed producing a polypeptide of about 10 kDa. By immunohistochemistry we localized the Pl APP antigen in some ser…

In vitro fibrillogenesis of the amyloid beta 1-42 peptide: cholesterol potentiation and aspirin inhibition.

2002

Understanding the formation of extracellular amyloid neurofibrillar bundles/senile plaques and their role in the development of Alzheimer's disease is of considerable interest to neuroscientists and clinicians. Major components of the extracellular neurofibrillar bundles are polymerized amyloid beta (Abeta) peptides (1-40), (1-42) and (1-43), derived in vivo from the soluble amyloid precursor protein (sAPP) by proteolytic (beta- and gamma-secretase) cleavage. The Abeta(1-42) peptide is widely considered to be of greatest significance in relation to the pathogenesis of Alzheimer's disease. A well-defined ultrastructural characteristic within Alzheimer dense plaques is the presence of helical…

Cholesterol binding to amyloid-β fibrils: A TEM study

2008

There is increasing interest in the role of brain cholesterol in Alzheimer's disease and the contribution of cholesterol to the formation of amyloid plaques. This paper presents a TEM study showing the binding of soluble approximately 10 nm diameter cholesterol-PEG 600 micelles to amyloid-beta(1-42) (Abeta(1-42)) fibrils formed either in the presence of this cholesterol derivative or to preformed fibrils generated under four different fibrillogenesis conditions. Specimens negatively stained with uranyl acetate revealed that during 24 h fibrillogenesis at 37 degrees C the cholesterol-PEG micelles bound periodically to Abeta(1-42) protofibrils and apparently also formed a thin smooth unbroken…