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The size of amyloid seeds is known to modulate their autocatalytic amplification and cellular toxicity. However, the seed size-dependent secondary nucleation mechanism, toxicity, and disease-associated biological processes mediated by α-synuclein (α-Syn) fibrils are largely unknown. Using the cellular model and

Synucleinopathies are a class of neurodegenerative diseases, including Parkinson's disease (PD), Dementia with Lewy bodies (DLB), and Multiple System Atrophy (MSA). The common pathological hallmark of synucleinopathies is the filamentous α-synuclein (α-Syn) aggregates along with membrane components in cytoplasmic inclusions in the brain. β-Synuclein (β-Syn), an isoform of α-Syn, inhibits α-Syn aggregation and prevents its neurotoxicity, suggesting the neuroprotective nature of β-Syn. However, this notion changed with the discovery of disease-associated β-Syn mutations, V70M and P123H, in patients with DLB. It is still unclear how these missense mutations alter the structural and amyloidogenic properties of β-Syn, leading to neurodegeneration. Here, we characterized the biophysical properties and investigated the effect of mutations on β-Syn fibrillation under different conditions. V70M and P123H show high membrane binding affinity compared to wild-type β-Syn, suggesting their potential role in membrane interactions. β-Syn and its mutants do not aggregate under normal physiological conditions; however, the proteins undergo self-polymerization in a slightly acidic microenvironment and/or in the presence of an inducer, forming long unbranched amyloid fibrils similar to α-Syn. Strikingly, V70M and P123H mutants exhibit accelerated fibrillation compared to native β-Syn under these conditions. NMR study further revealed that these point mutations induce local perturbations at the site of mutation in β-Syn. Overall, our data provide insight into the biophysical properties of disease-associated β-Syn mutations and demonstrate that these mutants make the native protein more susceptible to aggregation in an altered microenvironment.

α-Synuclein (α-Syn) aggregation and amyloid formation is directly linked with Parkinson's disease pathogenesis. However, the early events involved in this process remain unclear. Here, using the in vitro reconstitution and cellular model, we show that liquid-liquid phase separation of α-Syn precedes its aggregation. In particular, in vitro generated α-Syn liquid-like droplets eventually undergo a liquid-to-solid transition and form an amyloid hydrogel that contains oligomers and fibrillar species. Factors known to aggravate α-Syn aggregation, such as low pH, phosphomimetic substitution and familial Parkinson's disease mutations, also promote α-Syn liquid-liquid phase separation and its subsequent maturation. We further demonstrate α-Syn liquid-droplet formation in cells. These cellular α-Syn droplets eventually transform into perinuclear aggresomes, the process regulated by microtubules. This work provides detailed insights into the phase-separation behaviour of natively unstructured α-Syn and its conversion to a disease-associated aggregated state, which is highly relevant in Parkinson's disease pathogenesis.

Liquid-liquid phase separation (LLPS) has emerged as a crucial biological mechanism for sequestering macromolecules (such as proteins and nucleic acids) into membraneless organelles in cells. Unstructured and intrinsically disordered domains are known to facilitate multivalent interactions driving protein LLPS. We hypothesized that LLPS could be an intrinsic property of proteins/polypeptides at their high intermolecular interaction regime. To examine this, we studied many (a total of 23) proteins/polypeptides with different structures and sequences for LLPS study using molecular crowder polyethylene glycol (PEG-8000). We showed that all proteins and even highly charged polypeptides (under study) can undergo liquid condensate formation, however with different phase space and conditions. Using a single component and combinations of protein multicomponent (co-LLPS) systems, we establish that a variety of intermolecular interactions can drive proteins/polypeptides LLPS.

The size of the amyloid seeds is known to modulate their autocatalytic amplification and cellular toxicity. However, the seed size-dependent secondary nucleation mechanism, toxicity, and disease-associated biological processes mediated by α-synuclein (α-Syn) fibrils are largely unknown. Using the cellular model and in vitro reconstitution, we showed that the size of α-Syn fibril seeds not only dictates its cellular internalization and associated cell death; but also the distinct mechanisms of fibril amplification pathways involved in the pathological conformational change of α-Syn. Specifically, small-sized fibril seeds showed elongation possibly through monomer addition at the fibril termini; whereas longer fibrils template the fibril amplification by surface-mediated nucleation as demonstrated by super-resolution microscopy. The distinct mechanism of fibril amplification, and cellular uptake along with toxicity suggest that breakage of fibrils into different sizes of seeds determine the underlying pathological outcome of synucleinopathies.

Liquid-liquid phase separation (LLPS) and subsequent liquid-to-solid transition is implicated in membraneless organelles formation as well as disease associated protein aggregation. However, how liquid-to-solid transition is initiated inside a liquid droplet remains unclear. Here, using studies at single droplet resolution, we show that liquid-to-solid transition of α-synuclein (α-Syn) liquid droplets is associated with significant changes in the local microenvironment as well as secondary structure of the protein, which is prominently observed at the center of the liquid droplets. With the ageing of liquid droplets, the “structured” core at the center gradually expands and propagates over entire droplets. Further, during droplet fusion, smaller, homogeneous droplets progressively dissolve and supply proteins to the larger, heterogeneous droplets containing solid-like core at their center. The present study will significantly help to understand the physical mechanism of LLPS and liquid-to-solid transition in biological compartmentalization as well as in protein aggregation associated with human neurodegenerative disorders.Abstract Figure

Supplier selection is the process by which firms identify, evaluate and contract with suppliers. The supplier selection process deploys a tremendous amount of a firm’s operational and financial resources and is considered as an important determinant of the success of its supply chain. In spite of being strategically important to organizations, the decision for supplier selection is often complex and unstructured. Furthermore, it is inherently a multi-criterion decision-making (MCDM) problem, which pertains to structuring and solving decision problems involving multiple criteria. The paper provides a framework to analyze and evaluate supplier selection in Indian pharmaceutical sector (IPS) using MCDM technique of fuzzy analytic hierarchy process. It intends to improve managerial decision-making in the IPS in developing a supplier selection strategy based on multi-criteria evaluation technique.

Synergistic-aggregation and cross-seeding by two different proteins/peptides in the amyloid aggregation are well evident in various neurological disorders including Alzheimer's disease. Here, we show co-storage of human Prolactin (PRL), which is associated with lactation in mammals, and neuropeptide galanin (GAL) as functional amyloids in secretory granules (SGs) of the female rat. Using a wide variety of biophysical studies, we show that irrespective of the difference in sequence and structure, both hormones facilitate their synergic aggregation to amyloid fibrils. Although each hormone possesses homotypic seeding ability, a unidirectional cross-seeding of GAL aggregation by PRL seeds and the inability of cross seeding by mixed fibrils suggest tight regulation of functional amyloid formation by these hormones for their efficient storage in SGs. Further, the faster release of functional hormones from mixed fibrils compared to the corresponding individual amyloid, suggests a novel mechanism of heterologous amyloid formation in functional amyloids of SGs in the pituitary.The formation of plaques of proteins called ‘amyloids’ in the brain is one of the hallmark characteristics of both Alzheimer’s and Parkinson’s disease, but amyloids can form in many tissues and organs, often disrupting normal activity. A lot of the research into amyloids has focused on their role in disease, but it turns out that amyloids can also appear in healthy tissues. For example, some protein hormones form amyloids that act as storage depots, helping cells to release the hormone when it is needed. Normally, amyloids are made mostly of a single type of protein or protein fragment associated with a particular disease like Alzheimer's. Often, this type of amyloid promotes plaque formation in other proteins, which aggravates other diseases (for example, the amyloids that form in Alzheimer’s can lead to Parkinson’s disease or type II diabetes getting worse).The plaques start growing from small amyloid fragments called seeds. In mixed amyloids – amyloids made of two types of proteins – seeds made of one protein can trigger the formation of amyloids of the other protein. This raises the question, is this true for hormones? The body often releases more than one hormone at a time from the same tissue; for example, the pituitary gland releases prolactin and galanin simultaneously. However, these hormones have completely different structures, so whether they can form a mixed amyloid is unclear. To answer this question, Chatterjee et al. first determined that, within the pituitary gland of female rats, prolactin and galanin could be found together in the same cells, forming mixed amyloids. To understand out how this happens, Chatterjee et al. tried seeding new amyloids using either prolactin or galanin. This revealed that only prolactin seeds were able to trigger the formation of galanin amyloids. Chatterjee et al. also found that the mixed amyloids could release the hormones faster than amyloids made from either protein alone. Together, these results suggest that the collaboration between these two proteins may help maintain hormone balance in the body. Problems with hormone storage and release lead to various human diseases, including prolactinoma. Understanding amyloid storage depots could reveal new ways to control hormone levels. Further research could also help to explain more about well-studied diseases linked to amyloids, like Alzheimer's.

Synergistic-aggregation and cross-seeding by two different amyloid proteins/peptides are well evident in various neurological disorders. However, this phenomenon is not well studied in functional amyloid aggregation. Here, we show Prolactin (PRL) is associated with lactation in mammals and neuropeptide galanin (GAL), which are co-stored in the lactotrophs facilitates the synergic aggregation in the absence of secretory granules helper molecules glycosaminoglycans (GAGS). Interestingly, although each partner possesses homotypic seeding ability, a unidirectional cross-seeding of GAL aggregation can be mediated by PRL seeds. The specificity of co-aggregation by PRL and GAL along with unidirectional cross-seeding suggests tight regulation of functional amyloid formation during co-storage of these hormones in secretory granule biogenesis of female rat lactotrophs. Further mixed fibrils release the constituent functional hormone much faster than the corresponding individual amyloid formed in presence of GAGs, suggesting that co-aggregation of functionally distant hormones might have evolved for efficient storage, synergistic and rapid release of both hormones upon stimulation. The co-aggregation and cross seeding by two different hormones of completely different structures and sequences (PRL and GAL) suggest a novel mechanism of heterologous amyloid formation both in disease and functional amyloids.

Biomaterials mimicking extracellular matrices (ECM) for three-dimensional (3D) cultures have gained immense interest in tumor modeling and in vitro organ development. Here, we introduce versatile, thixotropic amyloid hydrogels as a bio-mimetic ECM scaffold for 3D cell culture as well as high-throughput tumor spheroid formation using a drop cast method. The unique cross-β-sheet structure, sticky surface, and thixotropicity of amyloid hydrogels allow robust cell adhesion, survival, proliferation, and migration, which are essential for 3D tumor modeling with various cancer cell types. The spheroids formed show overexpression of the signature cancer biomarkers and confer higher drug resistance compared to two-dimensional (2D) monolayer cultures. Using breast tumor tissue from mouse xenograft, we showed that these hydrogels support the formation of tumor spheroids with a well-defined necrotic core, cancer-associated gene expression, higher drug resistance, and tumor heterogeneity reminiscent of the original tumor. Altogether, we have developed a rapid and cost-effective platform for generating in vitro cancer models for the screening of anti-cancer therapeutics and developing personalized medicines.

Amyloids are highly ordered nanofibrils and their tensile strength is similar to that of steel, which makes them resistant to extreme pH and temperature. Based on this rationale, we demonstrate a facile synthesis of palladium, copper, platinum, gold and silver nanocomposites using α-Synuclein (α-Syn) fibrils as a template. We showed that an α-Syn-fibril-palladium nanoparticles (α-Syn-PdNPs) composite can be used as a heterogeneous catalyst in C–H bond activation and the electrooxidation of ethanol. The study demonstrated α-Syn-PdNPs to be a superior heterogeneous catalyst for the synthesis of pharmaceutically valuable benzofuran, naphthofuran, coumarin and N-arylindole via C–H activation. Further, the electrooxidation of ethanol using α-Syn-PdNPs displayed an electrochemically active surface area of 160.6 m2 g−1, which is much higher than the previously reported values for supported Pd nanocomposites.

Amyloid fibrils are cross-β-sheet-rich protein/peptide fibrils that are typically associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Recently, functional amyloids have been discovered where amyloids are implicated in performing normal physiological functions of the host organism rather than creating diseases. The ability of amyloids to interact with the cell membrane and other small biomolecules exhibits its great potential to be used as a biomaterial for cell adhesion and gene delivery system. Given the established ability of semen-derived amyloids to concentrate HIV in semen and that of charged polymers as an enhancer of retroviral gene transfer, we hypothesized that charged amyloid fibrils can augment virus-mediated delivery system. We show that amyloids of α-synuclein formed in the presence and absence of cationic polymers chitosan and amyloid of poly-l-lysine can interact with lentiviral particles and enhance transduction efficiency in cells. The amyloid nanofibrils increase transduction efficiency up to ∼4 fold similar to widely used cationic polymer Polybrene. This study shows that amyloid nanofibril scaffolds may be used as targeted gene delivery systems.

In the present day, business environment marked by intense competition and uncertainties, the ability of an organization and its supply chain to respond quickly to an unforeseen change in the business environment forms the key to its sustenance in the market. Since an agile supply chain comprises of a plethora of components, it is imperative that there should be a set of uncertainties associated with its functioning. The purpose of this paper is to evaluate a set of critical risks associated with the agility of an organization's supply chain. Identification and prioritization of the risks to assess their relative criticality form the backbone of the research process. This research is expected to aid the decision-makers develop robust risk management strategies as related to their organizational supply chain agility, thereby ensuring their growth and sustainability in the market.

In the present day, business environment marked by intense competition and uncertainties, the ability of an organization and its supply chain to respond quickly to an unforeseen change in the business environment forms the key to its sustenance in the market. Since an agile supply chain comprises of a plethora of components, it is imperative that there should be a set of uncertainties associated with its functioning. The purpose of this paper is to evaluate a set of critical risks associated with the agility of an organization's supply chain. Identification and prioritization of the risks to assess their relative criticality form the backbone of the research process. This research is expected to aid the decision-makers develop robust risk management strategies as related to their organizational supply chain agility, thereby ensuring their growth and sustainability in the market.

α-Synuclein (α-Syn) aggregation and amyloid formation is directly linked with Parkinson's disease pathogenesis. However, the early events involved in this process remain unclear. Here, using the in vitro reconstitution and cellular model, we show that liquid-liquid phase separation of α-Syn precedes its aggregation. In particular, in vitro generated α-Syn liquid-like droplets eventually undergo a liquid-to-solid transition and form an amyloid hydrogel that contains oligomers and fibrillar species. Factors known to aggravate α-Syn aggregation, such as low pH, phosphomimetic substitution and familial Parkinson's disease mutations, also promote α-Syn liquid-liquid phase separation and its subsequent maturation. We further demonstrate α-Syn liquid-droplet formation in cells. These cellular α-Syn droplets eventually transform into perinuclear aggresomes, the process regulated by microtubules. This work provides detailed insights into the phase-separation behaviour of natively unstructured α-Syn and its conversion to a disease-associated aggregated state, which is highly relevant in Parkinson's disease pathogenesis.

SUMMARYα-Synuclein (α-Syn) aggregation and amyloid formation is directly linked with Parkinson’s disease (PD) pathogenesis. However, the early events involved in this process remain unclear. Here, using in vitro reconstitution and cellular model, we show that liquid-liquid phase separation (LLPS) of α-Syn precedes its aggregation. In particular, in vitro generated α-Syn liquid-like droplets eventually undergo a liquid-to-solid transition and form amyloid-hydrogel containing oligomers and fibrillar species. Factors known to aggravate α-Syn aggregation such as low pH, phosphomimic substitution, and familial PD mutation also promote α-Syn LLPS and its subsequent maturation. We further demonstrate α-Syn liquid droplet formation in cells, under oxidative stress. These cellular α-Syn droplets eventually transform into perinuclear aggresomes, the process regulated by microtubules. The present work provides detailed insights into the phase separation behavior of natively unstructured α-Syn and its conversion to a disease-associated aggregated state, which is highly relevant in PD pathogenesis.

Parkinson's disease is mainly a sporadic disorder in which both environmental and cellular factors play a major role in the initiation of this disease. Glycosaminoglycans (GAG) are integral components of the extracellular matrix and are known to influence amyloid aggregation of several proteins, including α-synuclein (α-Syn). However, the mechanism by which different GAGs and related biological polymers influence protein aggregation and the structure and intercellular spread of these aggregates remains elusive. In this study, we used three different GAGs and related charged polymers to establish their role in α-Syn aggregation and associated biological activities of these aggregates. Heparin, a representative GAG, affected α-Syn aggregation in a concentration-dependent manner, whereas biphasic α-Syn aggregation kinetics was observed in the presence of chondroitin sulfate B. Of note, as indicated by 2D NMR analysis, different GAGs uniquely modulated α-Syn aggregation because of the diversity of their interactions with soluble α-Syn. Moreover, subtle differences in the GAG backbone structure and charge density significantly altered the properties of the resulting amyloid fibrils. Each GAG/polymer facilitated the formation of morphologically and structurally distinct α-Syn amyloids, which not only displayed variable levels of cytotoxicity but also exhibited an altered ability to internalize into cells. Our study supports the role of GAGs as key modulators in α-Syn amyloid formation, and their distinct activities may regulate amyloidogenesis depending on the type of GAG being up- or down-regulated in vivo.

The involvement of α-synuclein (α-Syn) amyloid formation in Parkinson's disease (PD) pathogenesis is supported by the discovery of α-Syn gene (SNCA) mutations linked with familial PD, which are known to modulate the oligomerization and aggregation of α-Syn. Recently, the A53V mutation has been discovered, which leads to late-onset PD. In this study, we characterized for the first time the biophysical properties of A53V, including the aggregation propensities, toxicity of aggregated species, and membrane binding capability, along with those of all familial mutations at the A53 position. Our data suggest that the A53V mutation accelerates fibrillation of α-Syn without affecting the overall morphology or cytotoxicity of fibrils compared to those of the wild-type (WT) protein. The aggregation propensity for A53 mutants is found to decrease in the following order: A53TA53VWTA53E. In addition, a time course aggregation study reveals that the A53V mutant promotes early oligomerization similar to the case for the A53T mutation. It promotes the largest amount of oligomer formation immediately after dissolution, which is cytotoxic. Although in the presence of membrane-mimicking environments, the A53V mutation showed an extent of helix induction capacity similar to that of the WT protein, it exhibited less binding to lipid vesicles. The nuclear magnetic resonance study revealed unique chemical shift perturbations caused by the A53V mutation compared to those caused by other mutations at the A53 site. This study might help to establish the disease-causing mechanism of A53V in PD pathology.

Current day business organizations, symbolized by complex and global supply chains, are often subjected to unforeseen threats that result in huge financial losses. There are no sure ways of assessing these threats, especially the “black swans” (high-impact, but low-probability events like natural disasters, terrorist attacks, outbreaks, etc.), as the severe dearth of historical data excludes the use of forecasting tools to evaluate those disruptions. However, it has been observed that some organizations cope far better than others in addressing these unforeseen and unquantifiable disruptions. This is not because they have a ‘secret formula’, but due to them sharing a critical trait known as resilience. The notion of supply chain resiliency, which is the ability of a supply chain to recover to the ‘pre-disruption’ or a better state after suffering through a disruption process, has always been considered as a core element in the success of an organization. The primary objective of this chapter is to familiarize the readers with the concept of supply chain resiliency and its role in mitigating supply chain disruptions. The chapter will also reveal the advantages of a resilient supply chain through insightful examples from a wide range of industries.

Manufacturing and service organisations have repeatedly stressed the importance of knowledge management and sharing as an integral part of their growth and business strategy. Unfortunately, knowledge sharing (KS) barriers or factors can have a negative influence on a new product development (NPD) project team performance can make it difficult for the organisation to achieve sustained superior performance. The purpose of this research is to identify and explore a set of important KS barriers that might negatively affect the performance of a NPD project team. Specifically, this research focussed on identifying and evaluating the barriers to development and to offer guidelines to decision makers to improve KS to foster effective processes. This research can be utilised by decision-makers to design and develop effective processes and mitigation strategies to ensure effective KS.

One of the primary design goals of wireless multi-media communication systems is to optimize the quality of user experience. This metric is often quantified using the end-to-end distortion between the original source at the encoder and the reconstructed version of it at the destination. Considering this performance metric, optimal multimedia transmission schemes using joint source-channel coding (JSCC) for fading cognitive radio networks are studied in this paper. Different underlay transmission protocols, based on single- or multi-user receiver capabilities, are compared in terms of their average distortion performance, using an outage analysis. It is demonstrated that JSCC provides significant performance gains over goodput-maximizing schemes that rely on the optimality of source-channel separation, and that, for the scenarios evaluated, one of the proposed protocols with JSCC achieves average distortion performance very close to a lower bound obtained by ignoring the primary interference.

Coding for the causal cognitive radio channel, with the cognitive source subjected to a half-duplex constraint, is studied. A discrete memoryless channel model incorporating the half-duplex constraint is presented, and a new achievable rate region is derived for this channel. It is proved that this rate region contains the previously known causal achievable rate region of \cite{Devroye06} for Gaussian channels., 5 pages, 2 figures, ISIT 2010

The problems of resource allocation and the characterization of cooperative behavior in a two-user fading multiple-access channel (MAC) in the presence of uncertainty about the channel state information at the transmitters (CSIT) are considered. Game-theoretic techniques are used to characterize cooperative behavior and obtain the system operation point from an individualistic perspective. A two-user bargaining problem formulation, with the utility function being defined as the average rate each user can achieve, is used to obtain a fair and efficient operating point. It is shown that for the conventional bargaining problem formulation, the Nash Bargaining Solution (NBS) is very sensitive to the CSIT, and hence may result in considerable performance degradation. A modified bargaining problem formulation, that does not require an explicit modeling of the actual CSIT error, is proposed to address this issue, and shown to provide significant robustness to the system.

In this paper, communication through an overlay cognitive radio network, wherein the cognitive ability of a secondary source needs to be acquired, i.e. the primary message may only be obtained by the cognitive source in a causal manner, is considered. A new achievable rate region for the discrete memoryless version of this network is derived using block Markov superposition coding (SPC), conditional rate-splitting, conditional Gel'fand-Pinkser (GP) binning, and cooperative relaying. This rate region is evaluated for Gaussian channels, and numerical results are presented to demonstrate the contributions of the various coding strategies, used in the proposed coding scheme, towards enlarging the achievable rate region.

Consider a two-user fading cooperative multiple-access channel (CMAC), where each user, along with transmitting its own information to the destination, helps the other user by forwarding the latterpsilas information. It is assumed that the transceivers (nodes) are capable of half-duplex communication and that full channel state information (CSI) is available at all the nodes. Cooperative transmission strategies based on a flow-theoretic approach are proposed. The proposed strategies include a sub-optimal but simple orthogonal relaying strategy for the CMAC (OR-CMAC), and a flow-optimized strategy for the CMAC (FO-CMAC). The proposed protocols are evaluated in terms of achievable rate regions and outage performances, for different scenarios. The boundaries of the achievable rate regions for the proposed strategies are characterized by convex optimization formulations, and FO-CMAC is shown to provide improved achievable rate regions as compared to the conventional multiple-access channel (MAC), and a previously proposed strategy based on the decode-and-forward (DF) approach. Although sub-optimal in terms of the achievable rate region, OR-CMAC is shown to provide outage performance close to FO-CMAC for the scenarios considered. Moreover, by comparing to a lower bound on the outage probability, both the proposed strategies are shown to achieve the optimal diversity order of two for the required rate region of interest.