Dimensionality of Carbon Nanomaterials Determines the Binding and Dynamics of Amyloidogenic Peptides: Multiscale Theoretical Simulations

Experimental studies have demonstrated that nanoparticles can affect the rate of protein self-assembly, possibly interfering with the development of protein misfolding diseases such as Alzheimer's, Parkinson's and prion disease caused by aggregation and fibril formation of amyloid-prone proteins. We employ classical molecular dynamics simulations and large-scale density functional theory calculations to investigate the effects of nanomaterials on the structure, dynamics and binding of an amyloidogenic peptide apoC-II(60-70). We show that the binding affinity of this peptide to carbonaceous nanomaterials such as C60, nanotubes and graphene decreases with increasing nanoparticle curvature. Strong binding is facilitated by the large contact area available for π-stacking between the aromatic residues of the peptide and the extended surfaces of graphene and the nanotube. The highly curved fullerene surface exhibits reduced efficiency for π-stacking but promotes increased peptide dynamics. We postulate that the increase in conformational dynamics of the amyloid peptide can be unfavorable for the formation of fibril competent structures. In contrast, extended fibril forming peptide conformations are promoted by the nanotube and graphene surfaces which can provide a template for fibril-growth

The Essential Elements of a Risk Governance Framework for Current and Future Nanotechnologies

Societies worldwide are investing considerable resources into the safe development and use of nanomaterials. Although each of these protective efforts is crucial for governing the risks of nanomaterials, they are insufficient in isolation. What is missing is a more integrative governance approach that goes beyond legislation. Development of this approach must b

[Possibilities in the differential diagnosis of brain neoplasms using the long and short time sequences of proton magnetic resonance spectroscopy]

Item does not contain fulltextCurrently to perform proton magnetic resonance spectroscopy (1H MRS) with single voxel spectroscopy (SVS) technique long and/or short echo time sequences are used in order to provide complementary information. PURPOSE: The aim of the study was to compare the usefulness of STEAM (time echo, TE, 20 ms) and PRESS (TE 136 ms) sequences in the evaluation of brain neoplasms. MATERIALS AND METHOD: 15 healthy volunteers and 19 patients with brain tumors were examined using 1, 5 T MR scanner. MRI was performed with a standard protocol for brain neoplasms. 1H MRS with the SVS technique was performed after magnetic resonance imaging (MRI) using STEAM 20 and PRESS 136 sequences (voxel size 1 to 8 cc). RESULTS: In the STEAM sequence besides basic metabolites visible in PRESS as N-acetylaspartate, choline and creatine peaks of myoinositol and glutamate were visualized. Data obtained with short TE sequences in conjunction with long TE data were useful and in 5 cases necessary to identify the tumor type. These results were confirmed by pathology. CONCLUSIONS: The use of short TE sequences enables to visualize metabolites important for the diagnosis and differentiation of the tumor type. The combined information drawn out from both long and short TE spectra is also important

[Possibilities in the differential diagnosis of brain neoplasms using the long and short time sequences of proton magnetic resonance spectroscopy]

Currently to perform proton magnetic resonance spectroscopy (1H MRS) with single voxel spectroscopy (SVS) technique long and/or short echo time sequences are used in order to provide complementary information. PURPOSE: The aim of the study was to compare the usefulness of STEAM (time echo, TE, 20 ms) and PRESS (TE 136 ms) sequences in the evaluation of brain neoplasms. MATERIALS AND METHOD: 15 healthy volunteers and 19 patients with brain tumors were examined using 1, 5 T MR scanner. MRI was performed with a standard protocol for brain neoplasms. 1H MRS with the SVS technique was performed after magnetic resonance imaging (MRI) using STEAM 20 and PRESS 136 sequences (voxel size 1 to 8 cc). RESULTS: In the STEAM sequence besides basic metabolites visible in PRESS as N-acetylaspartate, choline and creatine peaks of myoinositol and glutamate were visualized. Data obtained with short TE sequences in conjunction with long TE data were useful and in 5 cases necessary to identify the tumor type. These results were confirmed by pathology. CONCLUSIONS: The use of short TE sequences enables to visualize metabolites important for the diagnosis and differentiation of the tumor type. The combined information drawn out from both long and short TE spectra is also important

[Brain metabolism alterations in patients with anorexia nervosa observed in 1H-MRS]

Contains fulltext : 48323.pdf (publisher's version ) (Open Access)The causes of metabolic brain changes in patients with anorexia nervosa are still not fully explained. The purpose of this study was to use the 1H-MRS method in investigating metabolic changes in the brain of patients with anorexia nervosa. We studied 10 patients for visible alternations in brain metabolism and compared the results to healthy controls. 1H-MRS was acquired by the method of single voxels in white and grey matter. Proton MRS was performed after image guided localization using stimulated echo acquisition mode (STEAM) sequence with a short echo time of 20 ms. For data evaluation we used standard Siemens software and the additional PC. Choosing of the MRS sequences was related with particular interest in metabolites of short time echo: myoinositol and lipids. Besides this we evaluated peaks of: N-acetylaspartate (NAN), creatine (Cr) and choline (Cho). The results show significant differences in the levels of metabolites connected with fatty metabolism. In white matter we observed the reduction of lip-peak. The data was evaluated approximately and presented as lip:Cr. We did not observe any differences in other metabolites. As far as we know similar results had been reported and our study confirmed significant disorders in metabolism of these chemicals in patients with anorexia nervosa

Explanations for Water Whitening in Secondary Dispersion and Emulsion Polymer Films

The loss of optical transparency when polymer films are immersed in water, which is called “water whitening,” severely limits their use as clear barrier coatings. It is found that this problem is particularly acute in films deposited from polymers synthesized via emulsion polymerization using surfactants. Water whitening is less severe in secondary dispersion polymers, which are made by dispersing solution polymers in water without the use of surfactants. NMR relaxometry in combination with optical transmission analysis and electron microscopy reveal that some of the water sorbed in emulsion polymer films is contained within nano-sized “pockets” or bubbles that scatter light. In contrast, the water in secondary dispersion polymer films is mainly confined at particle interfaces, where it scatters light less strongly and its molecular mobility is reduced. The addition of surfactant to a secondary dispersion creates a periodic structure that displays a stop band in the optical transmission. The total amount of sorbed water is not a good indicator of polymers prone to water whitening. Instead, the particular locations of the water within the film must be considered. Both the amount of water and the size of the local water regions (as are probed by NMR relaxometry) are found to determine water whitening

The Essential Elements of a Risk Governance Framework for Current and Future Nanotechnologies

Societies worldwide are investing considerable resources into the safe development and use of nanomaterials. Although each of these protective efforts is crucial for governing the risks of nanomaterials, they are insufficient in isolation. What is missing is a more integrative governance approach that goes beyond legislation. Development of this approach must be evidence based and involve key stakeholders to ensure acceptance by end users. The challenge is to develop a framework that coordinates the variety of actors involved in nanotechnology and civil society to facilitate consideration of the complex issues that occur in this rapidly evolving research and development area. Here, we propose three sets of essential elements required to generate an effective risk governance framework for nanomaterials. (1) Advanced tools to facilitate risk-based decision making, including an assessment of the needs of users regarding risk assessment, mitigation, and transfer. (2) An integrated model of predicted human behavior and decision making concerning nanomaterial risks. (3) Legal and other (nano-specific and general) regulatory requirements to ensure compliance and to stimulate proactive approaches to safety. The implementation of such an approach should facilitate and motivate good practice for the various stakeholders to allow the safe and sustainable future development of nanotechnology