scholarly journals On the Cluster Formation of α-Synuclein Fibrils

2021 ◽  
Vol 8 ◽  
Author(s):  
Marija Dubackic ◽  
Ilaria Idini ◽  
Veronica Lattanzi ◽  
Yun Liu ◽  
Anne Martel ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Simple Model ◽  
Small Angle Neutron Scattering ◽  
Cluster Formation ◽  
Lewy Bodies ◽  
Membrane Systems ◽  
Body Formation ◽  
Rigid Rod ◽  
Acidic Conditions ◽  
Dense Accumulation

The dense accumulation of α-Synuclein fibrils in neurons is considered to be strongly associated with Parkinson’s disease. These intracellular inclusions, called Lewy bodies, also contain significant amounts of lipids. To better understand such accumulations, it should be important to study α-Synuclein fibril formation under conditions where the fibrils lump together, mimicking what is observed in Lewy bodies. In the present study, we have therefore investigated the overall structural arrangements of α-synuclein fibrils, formed under mildly acidic conditions, pH = 5.5, in pure buffer or in the presence of various model membrane systems, by means of small-angle neutron scattering (SANS). At this pH, α-synuclein fibrils are colloidally unstable and aggregate further into dense clusters. SANS intensities show a power law dependence on the scattering vector, q, indicating that the clusters can be described as mass fractal aggregates. The experimentally observed fractal dimension was d = 2.6 ± 0.3. We further show that this fractal dimension can be reproduced using a simple model of rigid-rod clusters. The effect of dominatingly attractive fibril-fibril interactions is discussed within the context of fibril clustering in Lewy body formation.

scholarly journals Interaction between coxsackievirus B3 infection and α-synuclein in models of Parkinson’s disease

2021 ◽  
Vol 17 (10) ◽  
pp. e1010018
Author(s):  
Soo Jin Park ◽  
Uram Jin ◽  
Sang Myun Park
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Inclusion Body ◽  
Dopaminergic Neurons ◽  
Inclusion Bodies ◽  
Lewy Bodies ◽  
Coxsackievirus B3 ◽  
Body Formation ◽  
Inclusion Body Formation ◽  
Cvb3 Infection

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. PD is pathologically characterized by the death of midbrain dopaminergic neurons and the accumulation of intracellular protein inclusions called Lewy bodies or Lewy neurites. The major component of Lewy bodies is α-synuclein (α-syn). Prion-like propagation of α-syn has emerged as a novel mechanism in the progression of PD. This mechanism has been investigated to reveal factors that initiate Lewy pathology with the aim of preventing further progression of PD. Here, we demonstrate that coxsackievirus B3 (CVB3) infection can induce α-syn-associated inclusion body formation in neurons which might act as a trigger for PD. The inclusion bodies contained clustered organelles, including damaged mitochondria with α-syn fibrils. α-Syn overexpression accelerated inclusion body formation and induced more concentric inclusion bodies. In CVB3-infected mice brains, α-syn aggregates were observed in the cell body of midbrain neurons. Additionally, α-syn overexpression favored CVB3 replication and related cytotoxicity. α-Syn transgenic mice had a low survival rate, enhanced CVB3 replication, and exhibited neuronal cell death, including that of dopaminergic neurons in the substantia nigra. These results may be attributed to distinct autophagy-related pathways engaged by CVB3 and α-syn. This study elucidated the mechanism of Lewy body formation and the pathogenesis of PD associated with CVB3 infection.

Neutron Scattering from a Ferrofluid

1994 ◽  
Vol 376 ◽  
Author(s):  
Min Y. Lin ◽  
Weili Luo ◽  
Jeffrey Lynn
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Fractal Dimension ◽  
Neutron Scattering ◽  
Small Angle ◽  
Liquid State ◽  
Small Angle Neutron Scattering ◽  
Cluster Aggregation ◽  
High Concentrations ◽  
Average Size

ABSTRACTSmall angle neutron scattering experiments were performed on a eicosane-based ferrofluid. An average size of 88 Å can be extracted from the data, in agreement with results from electron microscopy. Below the frozen temperature of eicosane, however, the particles are seen to be in larger aggregates with a fractal dimension of 2.15, similar to those formed under reaction-limited cluster aggregation (RLCA) conditions. At high concentrations, particles form larger aggregates even in the liquid state. Applying a magnetic field introduces new structure and changes the density inside the aggregates.

Probing the Fractal Character of Pore Surfaces in Shale with Adsorption Technique

1998 ◽  
Vol 543 ◽  
Author(s):  
Jian Ma ◽  
Hao Qi ◽  
Po-Zen Wong
Keyword(s):  
Fractal Dimension ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Data ◽  
Adsorption Study ◽  
Fractal Surfaces ◽  
Adsorption Data ◽  
Fractal Character

AbstractWe report on an adsorption study on two shale samples that have previously been investigated by small-angle neutron scattering (SANS). The scattering data indicate that these samples can be characterized as surface fractals in length from 5 Å to 500 Å, with the fractal dimension D between 2.83 and 2.75. Using the existing models for adsorption on fractal surfaces, the values of D deduced from the adsorption data appear to be consistently lower than the SANS results. We discuss these findings.

STATISTICAL ANALYSIS OF CLUSTER STRUCTURES FORMED BY DIPOLE-DIPOLE INTERACTIONS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 912-917
Author(s):  
HISAO MORIMOTO ◽  
TORU MAEKAWA
Keyword(s):  
Magnetic Field ◽  
Fractal Dimension ◽  
Magnetic Dipole Moment ◽  
Control Parameter ◽  
Cluster Formation ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Dipole Interactions ◽  
High Fractal Dimension ◽  
Ferromagnetic Particles

We developed a statistical model of the cluster formation of ferromagnetic particles and analysed the cluster structures. We investigated the effect of the control parameter λ, that is, the ratio of magnetic dipole moment energy to thermal energy, and external magnetic fields on the fractal dimensions of three-dimensional ferromagnetic clusters. We found that the fractal dimension of clusters, D, changes from 5/3 to 2 as λ increases in the absence of a magnetic field. We also found that when clusters are subjected to a magnetic field, the fractal dimension decreases and the transition region from high fractal dimension to D=1 becomes shorter as λ increases.

A simple model of rigid rod adsorption

1977 ◽  
Vol 67 (3) ◽  
pp. 1061 ◽  
Author(s):  
R. E. Boehm ◽  
D. E. Martire
Keyword(s):  
Simple Model ◽  
Rigid Rod

Adsorption Monolayer Formation in Confined Geometry: Apparent Fractal Dimension

1996 ◽  
Vol 464 ◽  
Author(s):  
A.G. Qkunev ◽  
Yu.I. Aristov
Keyword(s):  
Fatty Acids ◽  
Fractal Dimension ◽  
Simple Model ◽  
Silica Surface ◽  
Adsorbed Layer ◽  
Silica Gels ◽  
Monolayer Formation ◽  
Adsorption Monolayer ◽  
Resolution Analysis ◽  
Surface Dimension

ABSTRACTHere we present experimental results on adsorption of fatty acids, aliphatic alcohols, and acetone on the mesoporous silica gels with various porosity. Conclusion has been drawn that fractal resolution analysis of the silica surface may lead to apparent values of the surface dimension. These data are suggested to be analyzed by a simple model taking into account adsorbed layer thickness and steric difficulties of monolayer formation in narrow pores.

Evolution of Structure-Scaling and Magnetic Properties during Thermal Loading of Melt-Spun Fe70Cr15B15(Sn) Alloys

2014 ◽  
Vol 215 ◽  
pp. 190-195 ◽  
Author(s):  
Tatiana A. Pisarenko ◽  
Anatoly Frolov ◽  
Galina Kraynova
Keyword(s):  
Magnetic Properties ◽  
Fractal Dimension ◽  
Contact Surface ◽  
Thermal Loading ◽  
Cluster Formation ◽  
Fractal Dimensionality ◽  
Percolation Cluster ◽  
Melt Spun ◽  
Evolution Of Structure ◽  
Kinetics Of

We have studied the scaling evolution of the structure and magnetic properties of the melt-spun Fe70Cr15B15(Sn) alloys. The magnetic percolation cluster about the percolation threshold forms at the vitrification stage that is determined by both the kinetics of magnetic and of transport properties and the variation of fractal dimensionality. Alloying by tin of contact surface of ribbon decreases the temperature of the cluster formation. It is shown that the evolution of a fractal ordering affects the kinetics of the physical properties of the alloys. The spectra of fractal dimensionality identify the symmetry character of melt-spun alloys. Fractal dimensionDfis reduced at the increasing complexity of hierarchical system.

scholarly journals Contrast Variation Small Angle Neutron Scattering Investigation of Micro- and Nano-Sized TATB

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2606 ◽  
Author(s):  
Panqi Song ◽  
Xiaoqing Tu ◽  
Liangfei Bai ◽  
Guangai Sun ◽  
Qiang Tian ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Fractal Structure ◽  
External Surface ◽  
Contrast Variation ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
Structure Surface

Small angle neutron scattering (SANS) with contrast variation was used to characterize the fractal behavior and embedded porosity of micro/nano-sized 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystallites, gauging the effects of particle sizes on the microstructural features. Scattering results reveal that the external surface of micro-sized TATB crystallites are continuous and smooth interfaces and their internal pores display a surface fractal structure (surface fractal dimension 2.15 < DS < 2.25), while the external surface of nano-sized TATB particles exhibit a surface fractal structure (surface fractal dimension 2.36 < DS < 2.55) and their internal pores show a two-level volume fractal structure (large voids consist of small voids). The voids volume fraction of nano-sized TATB particles are found increased distinctively when compared with micro-sized TATB particles on length scale between 1 nm and 100 nm. Specific surface areas are also estimated based on Porod law method, which are coincident with Brunauer-Emmett-Teller (BET) measurements. The contrast variation technique distinguishes the information of internal voids from external surface, suggesting SANS is a powerful tool for determining the microstructural features, which can be used to establish the relationship between microstructures and properties of micro/nano-energetic materials.

scholarly journals Differential Effects of Yeast NADH Dehydrogenase (Ndi1) Expression on Mitochondrial Function and Inclusion Formation in a Cell Culture Model of Sporadic Parkinson’s Disease

Biomolecules ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 119 ◽  
Author(s):  
Emily N. Cronin-Furman ◽  
Jennifer Barber-Singh ◽  
Kristen E. Bergquist ◽  
Takao Yagi ◽  
Patricia A. Trimmer
Keyword(s):  
Gene Expression ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Lewy Body ◽  
Complex I ◽  
Nadh Dehydrogenase ◽  
Lewy Bodies ◽  
Body Formation

Parkinson’s disease (PD) is a neurodegenerative disorder that exhibits aberrant protein aggregation and mitochondrial dysfunction. Ndi1, the yeast mitochondrial NADH dehydrogenase (complex I) enzyme, is a single subunit, internal matrix-facing protein. Previous studies have shown that Ndi1 expression leads to improved mitochondrial function in models of complex I-mediated mitochondrial dysfunction. The trans-mitochondrial cybrid cell model of PD was created by fusing mitochondrial DNA-depleted SH-SY5Y cells with platelets from a sporadic PD patient. PD cybrid cells reproduce the mitochondrial dysfunction observed in a patient’s brain and periphery and form intracellular, cybrid Lewy bodies comparable to Lewy bodies in PD brain. To improve mitochondrial function and alter the formation of protein aggregates, Ndi1 was expressed in PD cybrid cells and parent SH-SY5Y cells. We observed a dramatic increase in mitochondrial respiration, increased mitochondrial gene expression, and increased PGC-1α gene expression in PD cybrid cells expressing Ndi1. Total cellular aggregated protein content was decreased but Ndi1 expression was insufficient to prevent cybrid Lewy body formation. Ndi1 expression leads to improved mitochondrial function and biogenesis signaling, both processes that could improve neuron survival during disease. However, other aspects of PD pathology such as cybrid Lewy body formation were not reduced. Consequently, resolution of mitochondrial dysfunction alone may not be sufficient to overcome other aspects of PD-related cellular pathology.

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