Studies on the Role of Vitronectin and Plasminogen-Activator Inhibitor-1 Complexes Beyond Inhibiting Proteases: Binding to the Extracellular Matrix, Cell Interactions and Pathogenesis

Plasminogen activator inhibitor-1 (PAI-1), a member of the serine protease inhibitor (serpin) superfamily of proteins, circulates in blood in a complex with vitronectin (VN). These two proteins are also found localized together in the extracellular matrix in many different pathophysiological conditions. Both of these proteins are involved with a number of physiologically important processes. Though PAI-1 is a well-known inhibitor of serine proteases, more emphasis is now geared towards its protease independent functions. VN, on the other hand, is a binding protein that exists in the circulation in a preferred monomeric conformation. However, in the extracellular matrix, VN exists as multimer with altered conformation. Though the exact reason for such conformational alterations and compartmentalization is unknown, there are a number of biomolecules, including PAI-1 that are proposed to cause such alterations. In last few years, sufficient experimental evidence has been gathered to confirm this protease- independent effect of PAI-1 by which it induces multimerization of VN in a concentration-dependent fashion. It has been observed also that PAI-1 remains associated with this multimeric complex for several hours. A major focus of this dissertation work was to extend our understanding of the mechanism of the interaction between these proteins and to explore the physiological relevance of the multimeric complexes formed by their interaction on cellular adhesion and migration. In our study, emphasis has been given to the presence of an appropriate microenvironment so that the role of the multimeric complexes could be investigated in a relevant biological setting. Our findings indicate the importance of the surrounding microenvironment in establishing the specific role of the VN/PAI-1 complex in cell-matrix interactions. In a previous study from our lab, it was found that vitronectin knock-out mice were more resistant to Candida infection compared to wild type C57Bl/6 mice. One of the goals of this dissertation work was to provide a mechanistic explanation for their increased survival of the vitronectin knock-out mice upon Candida infection. Another important aspect of this work was to establish biophysical methods for understanding the structural changes that happen in PAI-1 naturally or due to ligand binding

Satellite Relayed Global Quantum Communication without Quantum Memory

Photon loss is the fundamental issue towards the development of quantum communication. We present a proposal to mitigate photon loss even at large distances and hence to create a global-scale quantum communication architecture. In this proposal, photons are sent directly through space, using a chain of co-moving low-earth orbit satellites. This satellite chain would bend the photons to move along the earth's curvature and control photon loss due to diffraction by effectively behaving like a set of lenses on an optical table. Numerical modeling of photon propagation through these "satellite lenses" shows that diffraction loss in entanglement distribution can be almost eliminated even at global distances of 20,000 km while considering beam truncation at each satellite and the effect of different errors. In the absence of diffraction loss, the effect of other losses (especially reflection loss) becomes important and they are investigated in detail. The total loss is estimated to be less than 30 dB at 20,000 km if other losses are constrained to 2% at each satellite, with 120 km satellite separation and 60 cm diameter satellite telescopes eliminating diffraction loss. Such low-loss satellite-based optical-relay protocol would enable robust, multi-mode global quantum communication and wouldn't require either quantum memories or repeater protocol. The protocol can also be the least lossy in almost all distance ranges available (200 - 20,000 km). Recent advances in space technologies may soon enable affordable launch facilities for such a satellite-relay network. We further introduce the "qubit transmission" protocol which has a plethora of advantages with both the photon source and the detector remaining on the ground. A specific lens setup was designed for the "qubit transmission" protocol which performed well in simulation that included atmospheric turbulence in the satellite uplink

PREPARATION, CHARACTERIZATION AND EVALUATION OF FLOATING MICROPARTICLES OF CIPROFLOXACIN

Objective: The main purpose of this study is to prepare a floating micro articulated drug delivery system of ciprofloxacin by using non-aqueous solvent evaporation technique to increase the bioavailability and therapeutic effectiveness of the drug by prolonging its gastric residence time.Methods: Floating microparticles were prepared by using different low-density polymers such as ethyl cellulose and hydroxypropyl methylcellulose either alone or in combination with the aid of non-aqueous solvent evaporation technique. All the formulated microparticles were subjected to various evaluation parameters such as percentage yield, drug content, drug entrapment, rheological studies, floating characteristics and in vitro drug release studies.Results: Drug-excipient compatibility studies performed with the help of FTIR instrument indicated that there were no interactions. Results revealed that non-aqueous solvent evaporation technique is a suitable technique for the preparation of floating microspheres as most of the formulations were discrete and spherical in shape with a good yield of 65% to 85% and 15 to 22 h of floating duration with 90% of maximum percentage floating capacity shown by formulation FM9. Though, different drug-polymer ratios, as well as a combination of polymers, play a significant role in the variation of overall characteristics of formulations. Based on the data of various evaluation parameters such as particle size analysis, drug content, drug entrapment, rheological studies and in vitro drug release characteristics formulation FM9 was found to fulfil the criteria of ideal floating drug delivery system.Conclusion: Floating microparticles were successfully prepared, and from this study, it can be concluded that the developed floating microspheres of ciprofloxacin can be used for prolonged drug release in the stomach to improve the bioavailability and patient compliance

Evaluation of Antibacterial Potential of Daldinia concentrica from North Eastern Region of India

Morphological, bio-chemical and antibacterial potential of an ascomycetous fungus, Daldinia concentrica, was evaluated. It was collected from dead, decaying log of Mimusops elengi tree and isolated by plating in potato dextrose medium. Macroscopic and microscopic features of the stromata were studied. The crude methanol extract of the stromata (30 mg/ml)  exhibited significant antibacterial activity against Escherichia coli (MTCC-40), Pseudomonas aeruginosa (MTCC-7093), Klebsiella pneumoniae (MTCC-661), Enterobacter aerogenes (MTCC-111) and Gram positive bacteria Staphylococcus aureus (MTCC-7443), Bacillus subtilis (MTCC-121). Bacillus subtilis was the most sensitive organism to the methanol extract of this fungus with 41.33 mm zone of inhibition. Gas Chromatographic–Mass Spectral Analysis of stromatal methanol extract revealed the presence of 19 compounds. The present investigation indicated the potential antibacterial activity of native D. concentrica, which could be useful for pharmaceutical application

Reducing Attack Surface of a Web Application by Open Web Application Security Project Compliance

The attack surface of a system is the amount of application area that is exposed to the adversaries. The overall vulnerability can be reduced by reducing the attack surface of a web application. In this paper, we have considered the web components of two versions of an in-house developed project management web application and the attack surface has been calculated prior and post open web application security project (OWASP) compliance based on a security audit to determine and then compare the security of this Project Management Application. OWASP is an open community to provide free tools and guidelines for application security. It was observed that the attack surface of the software reduced by 45 per cent once it was made OWASP compliant. The vulnerable surface exposed by the code even after OWASP compliance was due to the mandatory access points left in the software to ensure accessibility over a network.Defence Science Journal, 2012, 62(5), pp.324-330, DOI:http://dx.doi.org/10.14429/dsj.62.129

Distinct encounter complexes of PAI-1 with plasminogen activators and vitronectin revealed by changes in the conformation and dynamics of the reactive center loop

© 2015 The Protein Society Plasminogen activator inhibitor-1 (PAI-1) is a biologically important serine protease inhibitor (serpin) that, when overexpressed, is associated with a high risk for cardiovascular disease and cancer metastasis. Several of its ligands, including vitronectin, tissue-type and urokinase-type plasminogen activator (tPA, uPA), affect the fate of PAI-1. Here, we measured changes in the solvent accessibility and dynamics of an important unresolved functional region, the reactive center loop (RCL), upon binding of these ligands. Binding of the catalytically inactive S195A variant of tPA to the RCL causes an increase in fluorescence, indicating greater solvent protection, at its C-terminus, while mobility along the loop remains relatively unchanged. In contrast, a fluorescence increase and large decrease in mobility at the N-terminal RCL is observed upon binding of S195A-uPA to PAI-1. At a site distant from the RCL, binding of vitronectin results in a modest decrease in fluorescence at its proximal end without restricting overall loop dynamics. These results provide the new evidence for ligand effects on RCL conformation and dynamics and differences in the Michaelis complex with plasminogen activators that can be used for the development of more specific inhibitors to PAI-1. This study is also the first to use electron paramagnetic resonance (EPR) spectroscopy to investigate PAI-1 dynamics. Significance: Balanced blood homeostasis and controlled cell migration requires coordination between serine proteases, serpins, and cofactors. These ligands form noncovalent complexes, which influence the outcome of protease inhibition and associated physiological processes. This study reveals differences in binding via changes in solvent accessibility and dynamics within these complexes that can be exploited to develop more specific drugs in the treatment of diseases associated with unbalanced serpin activity

Demographic Inference and Representative Population Estimates from Multilingual Social Media Data

Social media provide access to behavioural data at an unprecedented scale and granularity. However, using these data to understand phenomena in a broader population is difficult due to their non-representativeness and the bias of statistical inference tools towards dominant languages and groups. While demographic attribute inference could be used to mitigate such bias, current techniques are almost entirely monolingual and fail to work in a global environment. We address these challenges by combining multilingual demographic inference with post-stratification to create a more representative population sample. To learn demographic attributes, we create a new multimodal deep neural architecture for joint classification of age, gender, and organization-status of social media users that operates in 32 languages. This method substantially outperforms current state of the art while also reducing algorithmic bias. To correct for sampling biases, we propose fully interpretable multilevel regression methods that estimate inclusion probabilities from inferred joint population counts and ground-truth population counts. In a large experiment over multilingual heterogeneous European regions, we show that our demographic inference and bias correction together allow for more accurate estimates of populations and make a significant step towards representative social sensing in downstream applications with multilingual social media.Comment: 12 pages, 10 figures, Proceedings of the 2019 World Wide Web Conference (WWW '19