Amit Singh

Bio: Amit Singh is an academic researcher from National Institute of Technology, Patna. The author has contributed to research in topics: Digital watermarking & Watermark. The author has an hindex of 57, co-authored 640 publications receiving 13795 citations. Previous affiliations of Amit Singh include Ithaca College & Center for Infectious Disease Research and Policy.

Combinatorial approach in the design of multifunctional polymeric nano-delivery systems for cancer therapy.

Abstract: There have been significant advances in our understanding of cancer as a disease at the molecular level. Combined with improved diagnostic systems, the concept of personalized medicine was introduced where therapy for every patient can be customized according to their disease profile. The nanotechnology approach for formulation design and the advent of drug delivery systems for small molecules and biologics has contributed to the development of personalized medicine. Despite the progress, effective management and treatment of cancer remains a clinical challenge. The majority of drug delivery vectors that have undergone clinical trials have been discontinued prematurely because of poor therapeutic outcomes, off-target effects and non-specific toxicity due to the components of the formulation itself. Therefore, there is an urgent unmet requirement for a systematic approach to design drug delivery vectors that not only deliver the cargo to the desired site of action, but are also highly biocompatible and non-toxic. The past decade has seen the evolution of a combinatorial approach to drug delivery, a concept that has been classically successful in drug discovery research. In the present review, we summarize the wet-lab and in silico strategies to designing libraries of biocompatible delivery materials using combinatorial chemistry and support this strategy with pre-clinical success stories in cancer therapy.

Multilevel Encrypted Text Watermarking on Medical Images Using Spread-Spectrum in DWT Domain

Abstract: This paper presents a secure multilevel watermarking scheme in which the encrypted text acts as a watermark. The algorithm is based on secure spread-spectrum technique for digital images in discrete wavelet transform (DWT) domain. Potential application of the proposed watermarking scheme is successfully demonstrated for embedding various medical watermarks in text format at different subband decomposition levels depending upon their performance requirements. In the embedding process, the cover CT Scan image is decomposed up to third level of DWT coefficients. Different text watermarks such as personal and medical record of the patient, diagnostic/image codes and doctor code/signature are embedded into the selective coefficients of the second and third level DWT for potential telemedicine applications. Selection of DWT coefficients for embedding is done by column wise thresholding of coefficients values. Also, encryption is applied to the ASCII representation of the text and the encoded text watermark is embedded. The algorithm correctly extracts the embedded watermarks without error and is robust against numerous known attacks without much degradation of the medical image quality of the watermarked image.

Reductive stress in microbes: implications for understanding Mycobacterium tuberculosis disease and persistence.

Abstract: Mycobacterium tuberculosis ( Mtb ) is a remarkably successful pathogen that is capable of persisting in host tissues for decades without causing disease. Years after initial infection, the bacilli may resume growth, the outcome of which is active tuberculosis (TB). In order to establish infection, resist host defences and re-emerge, Mtb must coordinate its metabolism with the in vivo environmental conditions and nutrient availability within the primary site of infection, the lung. Maintaining metabolic homeostasis for an intracellular pathogen such as Mtb requires a carefully orchestrated series of oxidation–reduction reactions, which, if unbalanced, generate oxidative or reductive stress. The importance of oxidative stress in microbial pathogenesis has been appreciated and well studied over the past several decades. However, the role of its counterpart, reductive stress, has been largely ignored. Reductive stress is defined as an aberrant increase in reducing equivalents, the magnitude and identity of which is determined by host carbon source utilisation and influenced by the presence of host-generated gases (e.g. NO, CO, O 2 and CO 2 ). This increased reductive power must be dissipated for bacterial survival. To recycle reducing equivalents, microbes have evolved unique electron ‘sinks’ that are distinct for their particular environmental niche. In this review, we describe the specific mechanisms that some microbes have evolved to dispel reductive stress. The intention of this review is to introduce the concept of reductive stress, in tuberculosis research in particular, in the hope of stimulating new avenues of investigation.

Mad2 Checkpoint Gene Silencing Using Epidermal Growth Factor Receptor-Targeted Chitosan Nanoparticles in Non-Small Cell Lung Cancer Model

Abstract: RNA interference has emerged as a powerful strategy in cancer therapy because it allows silencing of specific genes associated with tumor progression and resistance. Mad2 is an essential mitotic checkpoint component required for accurate chromosome segregation during mitosis, and its complete abolition leads to cell death. We have developed an epidermal growth factor receptor (EGFR)-targeted chitosan system for silencing the Mad2 gene as a strategy to efficiently induce cell death in EGFR overexpressing human A549 non-small cell lung cancer cells. Control and EGFR-targeted chitosan nanoparticles loaded with small interfering RNAs (siRNAs) against Mad2 were formulated and characterized for size, charge, morphology, and encapsulation efficiency. Qualitative and quantitative intracellular uptake studies by confocal imaging and flow cytometry, respectively, showed time-dependent enhanced and selective intracellular internalization of EGFR-targeted nanoparticles compared to nontargeted system. Targeted nanoparticles showed nearly complete depletion of Mad2 expression in A549 cells contrasting with the partial depletion in the nontargeted system. Accordingly, Mad2-silencing-induced apoptotic cell death was confirmed by cytotoxicity assay and flow cytometry. Our results demonstrate that EGFR-targeted chitosan loaded with Mad2 siRNAs is a potent delivery system for selective killing of cancer cells.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Pattern Recognition and Machine Learning

Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Harrison's Principles of Internal Medicine

Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Abstract: Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.