Chaperone protein HYPK interacts with the first 17 amino acid region of Huntingtin and modulates mutant HTT-mediated aggregation and cytotoxicity

Huntington's disease is a polyglutamine expansion disorder, characterized by mutant HTT-mediated aggregate formation and cytotoxicity. Many reports suggests roles of N-terminal 17 amino acid domain of HTT (HTT-N17) towards subcellular localization, aggregate formation and subsequent pathogenicity induced by N-terminal HTT harboring polyQ stretch in pathogenic range. HYPK is a HTT-interacting chaperone which can reduce N-terminal mutant HTT-mediated aggregate formation and cytotoxicity in neuronal cell lines. However, how HYPK interacts with N-terminal fragment of HTT remained unknown. Here we report that specific interaction of HYPK with HTT-N17 is crucial for the chaperone activity of HYPK. Deletion of HTT-N17 leads to formation of tinier, SDS-soluble nuclear aggregates formed by N-terminal mutant HTT. The increased cytotoxicity imparted by these tiny aggregates might be contributed due to loss of interaction with HYPK. (C) 2014 Elsevier Inc. All rights reserved.

Mixed Mode Analysis of Obliquely Oriented Edge Cracked Semicircular Disk Under Compression

A new mixed-mode compression fracture specimen, obliquely oriented edge cracked semicircular disk (OECSD) is analyzed by extending pure opening mode configuration of edge cracked semicircular disk (ECSD) under Hertzian compression. Photoelastic experiments are conducted on two different specimens of OECSD of same size and different crack lengths and inclinations. Finite element method (FEM) is used to solve a number of cases of the problem varying crack length and crack inclination. FE results show a good match with experiments. Inclination of edge crack in OECSD can be so made as to obtain any mode-mixity ratio between zero and one and beyond for any crack length. The new specimen can be used for fracture testing under compression more conveniently than the existing ones in several ways.

Suppression of protein aggregation by gold nanoparticles: a new way to store and transport proteins

Suppression of the aggregation of proteins has tremendous implications in biology and medicine. In the pharmaceuticals industry, aggregation of therapeutically important proteins and peptides while stored, reduces the efficacy and promptness of action leading to, in many instances, intoxication of the patient by the aggregate. Here we report the effect of gold nanoparticles (Au-NPs) in preventing the thermal and chemical aggregation of two unrelated proteins of different size, alcohol dehydrogenase (ADH, 84 kDa) and insulin (6 kDa), respectively, in physiological pH. Our principal observation is that there is a significant reduction (up to 95%) in the extent of aggregation of ADH and insulin in the presence of gold nanoparticles (Au-NPs). Aggregation of these proteins at micromolar concentration is prevented using nanomolar or less amounts of gold nanoparticles which is remarkable since chaperones which prevent such aggregation in vivo are required in micromolar quantity. The prevention of aggregation of these two different proteins under two different denaturing environments has established the role of Au-NPs as a protein aggregation prevention agent. The extent of prevention increases rapidly with the increase in the size of the gold nanoparticles. Protein molecules get physisorbed on the gold nanoparticle surface and thus become inaccessible by the denaturing agent in solution. This adsorption of proteins on AuNPs has been established by a variety of techniques and assays.

Curcumin Pyrazole and its derivative (N-(3-Nitrophenylpyrazole) Curcumin inhibit aggregation, disrupt fibrils and modulate toxicity of Wild type and Mutant alpha-Synuclein

Accumulating evidence suggests that deposition of neurotoxic a-synuclein aggregates in the brain during the development of neurodegenerative diseases like Parkinson's disease can be curbed by anti-aggregation strategies that either disrupt or eliminate toxic aggregates. Curcumin, a dietary polyphenol exhibits anti-amyloid activity but the use of this polyphenol is limited owing to its instability. As chemical modifications in curcumin confiscate this limitation, such efforts are intensively performed to discover molecules with similar but enhanced stability and superior properties. This study focuses on the inhibitory effect of two stable analogs of curcumin viz. curcumin pyrazole and curcumin isoxazole and their derivatives against a-synuclein aggregation, fibrillization and toxicity. Employing biochemical, biophysical and cell based assays we discovered that curcumin pyrazole (3) and its derivative N-(3-Nitrophenylpyrazole) curcumin (15) exhibit remarkable potency in not only arresting fibrillization and disrupting preformed fibrils but also preventing formation of A11 conformation in the protein that imparts toxic effects. Compounds 3 and 15 also decreased neurotoxicity associated with fast aggregating A53T mutant form of a-synuclein. These two analogues of curcumin described here may therefore be useful therapeutic inhibitors for the treatment of a-synuclein amyloidosis and toxicity in Parkinson's disease and other synucleinopathies.

Interferon-Gamma and Nitric Oxide Synthase 2 Mediate the Aggregation of Resident Adherent Peritoneal Exudate Cells: Implications for the Host Response to Pathogens

Interferon-gamma (Ifn gamma), a key macrophage activating cytokine, plays pleiotropic roles in host immunity. In this study, the ability of Ifn gamma to induce the aggregation of resident mouse adherent peritoneal exudate cells (APECs), consisting primarily of macrophages, was investigated. Cell-cell interactions involve adhesion molecules and, upon addition of Ifn gamma, CD11b re-localizes preferentially to the sites of interaction on APECs. A functional role of CD11b in enhancing aggregation is demonstrated using Reopro, a blocking reagent, and siRNA to Cd11b. Studies with NG-methyl-L-arginine (LNMA), an inhibitor of Nitric oxide synthase (Nos), NO donors, e.g., S-nitroso-N-acetyl-DL-penicillamine (SNAP) or Diethylenetriamine/ nitric oxide adduct (DETA/NO), and Nos2(-/-) mice identified Nitric oxide (NO) induced by Ifn gamma as a key regulator of aggregation of APECs. Further studies with Nos2(-/-) APECs revealed that some Ifn. responses are independent of NO: induction of MHC class II and CD80. On the other hand, Nos2 derived NO is important for other functions: motility, phagocytosis, morphology and aggregation. Studies with cytoskeleton depolymerizing agents revealed that Ifn gamma and NO mediate the cortical stabilization of Actin and Tubulin which contribute to aggregation of APECs. The biological relevance of aggregation of APECs was delineated using infection experiments with Salmonella Typhimurium (S. Typhimurium). APECs from orally infected, but not uninfected, mice produce high amounts of NO and aggregate upon ex vivo culture in a Nos2-dependent manner. Importantly, aggregated APECs induced by Ifn gamma contain fewer intracellular S. Typhimurium compared to their single counterparts post infection. Further experiments with LNMA or Reopro revealed that both NO and CD11b are important for aggregation; in addition, NO is bactericidal. Overall, this study elucidates novel roles for Ifn gamma and Nos2 in regulating Actin, Tubulin, CD11b, motility and morphology during the aggregation response of APECs. The implications of aggregation or ``group behavior'' of APECs are discussed in the context of host resistance to infectious organisms.

Investigation on the origin of exchange bias in epitaxial, oriented and polycrystalline Fe3O4 thin films

We observe exchange bias (EB) in a single magnetic film Fe3O4 at temperature T < 200 K. Irrespective of crystallographic orientations of grown Fe3O4; they exhibit similar nature of EB for (100) epitaxial, (111) oriented and polycrystalline Fe3O4 thin films. Growth induced defects such as anti-phase boundaries (APBs) in epitaxial Fe3O4 thin film is known to have an influence on the magnetic interaction. But, it is noticed that according to the common consensus of APBs alone cannot explain the origin of EB. If majority of APBs end up with mainly anti-ferromagnetic interactions across these boundaries together with the internal ordering modification in Fe3O4, then EB can emerge at low temperatures. Hence, we propose the idea of directional anti-ferromagnetic APB induced EB in Fe3O4 triggered by internal ordering for T <= 200 K. Similar arguments are extended to (111) oriented as well as polycrystalline Fe3O4 films where the grain boundaries can impart same consequence as that of APBs. (C) 2015 Author(s).

Flower-like porous cobalt(II) monoxide nanostructures as anode material for Li-ion batteries

In the present study, a microwave-assisted, solution-based route has been employed to obtain porous CoO nano structures. Detailed characterization reveals that the flower-like nanostructures comprise petal-like sheets, each of which is made of an ordered, porous arrangement of crystallites of CoO measuring about 6 nm. TEM analysis shows that each ``petal'' is an oriented aggregate of CoO nanocrystals, such aggregation promoted by the hydroxyl moieties derived from the solution. The structure provides a large specific area as well as the porosity desirable in electrodes in Li-ion batteries. Electrochemical measurements carried out on electrodes made of nanostructured CoO show excellent Li ion-storing capability. A specific capacitance of 779 mAh g(-1) has been measured at a specific current of 100 mA g(-1). Measurements show also excellent cyclability and coulombic efficiency. Impedance spectroscopy provides evidence for charge transfer occurring in the porous networks. (C) 2015 Elsevier B.V. All rights reserved.

Feasibility of Protein a for the Oriented Immobilization of Immunoglobulin on Silicon Surface for a Biosensor with Imaging Ellipsometry

The feasibility of using protein A to immobilize antibody on silicon surface for a biosensor with imaging ellipsometry was presented in this study. The amount of human IgG bound with anti-IgG immobilized by the protein A on silicon surface was much more than that bound with anti-IgG immobilized by physical adsorption. The result indicated that the protein A could be used to immobilize antibody molecules in a highly oriented manner and maintain antibody molecular functional configuration on the silicon surface. High reproducibility of the amount of antibody immobilization and homogenous antibody adsorption layer on surfaces could be obtained by this immobilization method. Imaging ellipsometry has been proven to be a fast and reliable detection method and sensitive enough to detect small changes in a molecular monolayer level. The combination of imaging ellipsometry and surface modification with protein A has the potential to be further developed into an efficient immunoassay protein chip.

Towards an Understanding of the Influence of Sedimentation on Colloidal Aggregation by Peclet Number

The Peclet number is a useful index to estimate the importance of sedimentation as compared to the Brownian motion. However, how to choose the characteristic length scale for the Peclet number evaluation is rather critical because the diffusion length increases as the square root of the time whereas the drifting length is linearly related to time. Our Brownian dynamics simulation shows that the degree of sedimentation influence on the coagulation decreases when the dispersion volume fraction increases. Therefore using a fixed length, such as the diameter of particle, as the characteristic length scale for Peclet number evaluation is not a good choice when dealing with the influence of sedimentation on coagulation. The simulations demonstrated that environmental factors in the coagulation process, such as dispersion volume fraction and size distribution, should be taken into account for more reasonable evaluation of the sedimentation influence.

Innovative capabilities, entrepreneurial process and the dynamic growth of university spin-outs: A process-oriented study with evidence from China

This research aims to develop a conceptual framework in order to enquire into the dynamic growth process of University Spin-outs (hereafter referred to as USOs) in China, attempting to understand the capabilities configuration that are necessary for the dynamic growth. Based on the extant literature and empirical cases, this study attempts to address the question how do USOs in China build and configure the innovative capabilities to cope with the dynamic growth. This paper aims to contribute to the existing literature by providing a theoretical discussion of the USOs' dynamic entrepreneurial process, by investigating the interconnections between innovation problem-solving and the required configuration of innovative capabilities in four growth phases. Further, it presents a particular interest on the impact to the USOs' entrepreneurial innovation process by the integrative capabilities, in terms of knowledge integration, alliance, venture finance and venture governance. To date, studies that have investigated the dynamic development process of USOs in China and have recognized the heterogeneity of USOs in terms of capabilities that are required for rapid growth still remain sparse. Addressing this research gap will be of great interest to entrepreneurs, policy makers, and venture investors. ©2009 IEEE.

Probing protein aggregation with quartz crystal microbalances.

The supra-molecular self-assembly of peptides and proteins is a process which underlies a range of normal and aberrant biological pathways in nature, but one which remains challenging to monitor in a quantitative way. We discuss the experimental details of an approach to this problem which involves the direct measurement in vitro of mass changes of the aggregates as new molecules attach to them. The required mass sensitivity can be achieved by the use of a quartz crystal transducer-based microbalance. The technique should be broadly applicable to the study of protein aggregation, as well as to the identification and characterisation of inhibitors and modulators of this process.

An In-Situ Observation On Initial Aggregation Process Of Colloidal Particles Near Three-Phase Contact Line Of Air, Water And Vertical Substrate

The self-assembling process near the three-phase contact line of air, water and vertical substrate is widely used to produce various kinds of nanostructured materials and devices. We perform an in-situ observation on the self-assembling process in the vicinity of the three phase contact line. Three kinds of aggregations, i.e. particle-particle aggregation, particle-chain aggregation and chain-chain aggregation, in the initial stage of vertical deposition process are revealed by our experiments. It is found that the particle particle aggregation and the particle-chain aggregation can be qualitatively explained by the theory of the capillary immersion force and mirror image force, while the chain-chain aggregation leaves an opening question for the further studies. The present study may provide more deep insight into the self-assembling process of colloidal particles.