Search results for " amyloid"

Ionic self-complementarity induces amyloid-like fibril formation in an isolated domain of a plant copper metallochaperone protein

2004

This article is available from: http://www.biomedcentral.com/1472-6807/4/7

Amyloid precursor protein in platelets: A peripheral marker for the diagnosis of sporadic AD

2001

BACKGROUND: An altered pattern of amyloid precursor protein (APP) forms consisting in a reduced ratio between the upper (130 kDa) and the lower (106 to 110 kDa) immunoreactivity bands has been described in platelets of patients with AD. OBJECTIVE: To evaluate the sensitivity and the specificity of platelet APP forms' ratio (APPr) as a marker for AD. METHODS: Eighty-five patients with probable AD and 95 control subjects (CON), including healthy individuals and neurologic patients, entered the study. Platelet APPr was evaluated by means of Western Blot analysis and immunostaining in the whole platelet homogenate, and calculated by the ratio between the optical density (OD) of the upper (130 k…

Amyloid precursor protein in platelets of patients with Alzheimer disease: effect of acetylcholinesterase inhibitor treatment.

2001

BACKGROUND:Amyloid precursor protein (APP) forms with apparent molecular weights of 130, 110, and 106 kd are present in human platelets. It has been demonstrated that Alzheimer disease (AD) is specifically associated with a decreased APP forms ratio in platelets. OBJECTIVE:To investigate whether acetylcholinesterase (AChE) inhibitor treatment modifies the ratio of platelet APP forms in patients with AD. PATIENTS AND METHODS:From a large sample of patients with probable AD, 30 with mild to moderate AD were selected. Each patient underwent a clinical evaluation including the Mini-Mental State Examination (MMSE) and platelet APP forms analysis at baseline and after 30 days. During this interva…

Glucagon fibril polymorphism reflects differences in protofilament backbone structure

2010

Amyloid fibrils formed by the 29-residue peptide hormone glucagon at different concentrations have strikingly different morphologies when observed by transmission electron microscopy. Fibrils formed at low concentration (0.25 mg/mL) consist of two or more protofilaments with a regular twist, while fibrils at high concentration (8 mg/mL) consist of two straight protofilaments. Here, we explore the structural differences underlying glucagon polymorphism using proteolytic degradation, linear and circular dichroism, Fourier transform infrared spectroscopy (FTIR), and X-ray fiber diffraction. Morphological differences are perpetuated at all structural levels, indicating that the two fibril class…

Valorization of apple peels through the study of the effects on the amyloid aggregation process of ?-casein

2021

Waste valorization represents one of the main social challenges when promoting a circular economy and environmental sustainability. Here, we evaluated the effect of the polyphenols extracted from apple peels, normally disposed of as waste, on the amyloid aggregation process of ?-casein from bovine milk, a well-used amyloidogenic model system. The effect of the apple peel extract on protein aggregation was examined using a thioflavin T fluorescence assay, Congo red binding assay, circular dichroism, light scattering, and atomic force microscopy. We found that the phenolic extract from the peel of apples of the cultivar "Fuji", cultivated in Sicily (Caltavuturo, Italy), inhibited ?-casein fib…

Bovine Serum Albumin protofibril-like aggregates formation: Solo but not simple mechanism

2011

We report an experimental study on the model protein Bovine Serum Albumin (BSA), with the aim of elucidating the mechanisms by which a fully folded globular protein undergoes different aggregation pathways leading to the formation of amyloid fibrils or amorphous aggregates. We observe thermally induced formation of fibrillar structures at pH far from the protein isoelectric point. The increase of electrostatic repulsion results in protein destabilization and in modifications of inter and intra-molecular interactions leading to the growth of fibril-like aggregates stabilized by inter-molecular-β sheets. The aggregation kinetics is studied by means of fluorescence techniques, light scattering…

Molecular mechanisms in thermally induced amyloid formation of Concanavalin A

2008

Interacting processes in protein coagulation

1999

A strong interest is currently focused on protein self-association and deposit. This usually involves conformational changes of the entire protein or of a fragment. It can occur even at low concentrations and is responsible for pathologies such as systemic amyloidosis, Alzheimer's and Prion diseases, and other neurodegenerative pathologies. Readily available proteins, exhibiting at low concentration self-association properties related to conformational changes, offer very convenient model systems capable of providing insight into this class of problems. Here we report experiments on bovine serum albumin, showing that the process of conformational change of this protein towards an intermedia…

Phasor FLIM analysis of Thioflavin T fluorescence in protein amyloid aggregates: Mapping molecular interactions.

Thioflavin T (ThT) is a worldwide used dye to monitor protein aggregation as it stains with a certain specificity amyloid structures. The interactions between ThT and its hosts are largely studied suggesting that fluorescence properties of this dye critically depend both on the environment rigidity, electrostatic and hydrophobic properties as well as on molecular details binding site structure. Here FLIM and phasor approach analysis are used to exploit ThT amyloid interactions and, in turn, to address polymorphism and structural heterogeneity of amyloid species mapping aggregate-to-aggregate structural differences and revealing details of molecular architecture within the same aggregate.

Myocardial contrast echocardiography in biopsy-proven primary cardiac amyloidosis.

2008

Abstract Cardiac vasculature is affected in 88-90% of patients with primary cardiac amyloidosis (CA). Myocardial contrast echocardiography (MCE) relies on the ultrasound detection of microbubble contrast agents that are solely confined to the intravascular space, and are therefore useful in the evaluation of flow in the microvasculature. This is the first case report describing the use of MCE during vasodilator stress to evaluate coronary flow reserve in a patient with biopsy-proven primary CA and angiographically normal coronaries. Qualitative MCE demonstrated delayed replenishment of microbubbles during peak stress; quantitative analysis was consistent with a reduction in total myocardial…