Vishal Gaurav

Bio: Vishal Gaurav is an academic researcher from University of Massachusetts Amherst. The author has contributed to research in topics: Medicine & Dermatology. The author has an hindex of 4, co-authored 8 publications receiving 425 citations. Previous affiliations of Vishal Gaurav include PES University.

Pharmaceutically Active Natural Product Synthesis and Supply via Plant Cell Culture Technology

Abstract: The chemical diversity of plant-derived natural products allows them to function in a multitude of ways including flavor enhancers, agricultural chemicals, and importantly, human medicinals Supply of pharmaceutically active natural products is often a challenge due to the slow growing nature of some species, low yields found in nature, and unpredictable variability in accumulation Several production options are available including natural harvestation, total chemical synthesis, semisynthesis from isolated precursors, and expression of plant pathways in microbial systems However, for some medicinal natural products, such as the anticancer agent paclitaxel, where low yields in nature, chemical complexity and lack of knowledge of the complete biosynthetic pathway, preclude many of these options, plant cell culture technology is an attractive alternative for supply Plant cell suspension cultures are amenable to scale-up, environmental optimization, and metabolic engineering This review focuses on some of the key challenges in utilizing and commercializing plant cell culture suspension technology, with a focus on pharmaceutically active natural products Recent research has been directed toward application of traditional strategies such as reactor design, cell immobilization, and enzyme elicitation as well as emerging strategies such as characterizing cellular heterogeneity and variability through flow cytometric techniques, metabolic engineering, and system-wide analysis

Comparison of voice activity detection algorithms for VoIP

Abstract: We discuss techniques for voice activity detection (VAD) for voice over Internet Protocol (VoIP). VAD aids in saving the bandwidth requirement of a voice session, thereby increasing the bandwidth efficiently. We compare the quality of speech, level of compression and computational complexity for three time-domain and three frequency-domain VAD algorithms. Implementation of time-domain algorithms is computationally simple. However, better speech quality is obtained with the frequency-domain algorithms. A comparison of the merits and demerits along with the subjective quality of speech after removal of silence periods is presented for all the algorithms. A quantitative measurement of speech quality for different algorithms is also presented.

VAD techniques for real-time speech transmission on the Internet

Abstract: We discuss techniques for voice activity detection (VAD) for voice over Internet Protocol (VoIP). VAD aids in reducing the bandwidth requirement of a voice session, thereby using bandwidth efficiently. Such a scheme would be implemented in the application layer. Thus the VAD is independent of the lower layers in the network stack (see Flood, J.E., "Telecommunications Switching - Traffic and Networks", Prentice Hall India). We compare four time-domain VAD algorithms in terms of speech quality, compression level and computational complexity. A comparison of the relative merits and demerits along with the subjective quality of speech after the pruning of silence periods is presented for all the algorithms. A quantitative measurement of speech quality for different algorithms is also presented.

Flow cytometric methods to investigate culture heterogeneities for plant metabolic engineering.

Abstract: Plant cell cultures provide an important method for production and supply of a variety of natural products, where conditions can be easily controlled, manipulated, and optimized Development and optimization of plant cell culture processes require both bioprocess engineering and metabolic engineering approaches Cultures are generally highly heterogeneous, with significant variability amongst cells in terms of growth, metabolism, and productivity of key metabolites Taxus cultures produce the important anti-cancer agent Taxol((R)) (ie, paclitaxel) and have demonstrated significant variability amongst cell populations in culture with regard to paclitaxel accumulation, cell cycle participation, and protein synthesis To fully understand the link between cellular metabolism and culture behavior and to enable targeted metabolic engineering approaches, cultures need to be studied at a single cell level This chapter describes the application of plant cell flow cytometric techniques to investigate culture heterogeneity at the single cell level, in order to optimize culture performance through targeted metabolic engineering Flow cytometric analytical methods are described to study Taxus single cells, protoplasts, and nuclei suspensions with respect to secondary metabolite accumulation, DNA content, cell size, and complexity Reproducible methods to isolate these single particle suspensions from aggregated Taxus cultures are discussed Methods to stain both fixed and live cells for a variety of biological markers are provided to enable characterization of cell phenotypes Fluorescence-activated cell sorting (FACS) methods are also presented to facilitate isolation of certain plant cell culture populations for both analysis and propagation of superior cell lines for use in bioprocesses

Review on host-pathogen interaction in dermatophyte infections.

Abstract: Dermatophytosis is a common superficial fungal infection of the skin and its appendages caused by dermatophytes. Recent times have witnessed a dynamic evolution of dermatophytes driven by their ecology, reproduction, pathogenicity and host immune response, influenced by population migration and socioeconomic status. Dermatophytes establish infection following successful adherence of arthroconidia to the surface of keratinized tissues. The proteolytic enzymes released during adherence and invasion not only ascertain their survival but also allow the persistence of infection in the host. While the cutaneous immune surveillance mechanism, after antigen exposure and presentation, leads to activation of T lymphocytes and subsequent clonal expansion generating effector T cells that differentially polarize to a predominant Th17 response, the response fails to eliminate the pathogen despite the presence of high levels of IFN-γ. In chronic dermatophytosis, antigens are a constant source of stimulus promoting a dysregulated Th17 response causing inflammation. The host-derived iTreg response fails to counterbalance the inflammation and instead polarizes to Th17 lineage, aggravating the chronicity of the infection. Increasing antifungal resistance and recalcitrant dermatophytosis has impeded the overall clinical remission. Human genetic research has the potential to generate knowledge to explore new therapeutic targets. The review focuses on understanding specific virulence factors involved in pathogenesis and defining the role of dysregulated host immune response against chronic dermatophytic infections for future management strategies.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Marine natural products: a new wave of drugs?

Abstract: The largely unexplored marine world that presumably harbors the most biodiversity may be the vastest resource to discover novel ‘validated’ structures with novel modes of action that cover biologically relevant chemical space. Several challenges, including the supply problem and target identification, need to be met for successful drug development of these often complex molecules; however, approaches are available to overcome the hurdles. Advances in technologies such as sampling strategies, nanoscale NMR for structure determination, total chemical synthesis, fermentation and biotechnology are all crucial to the success of marine natural products as drug leads. We illustrate the high degree of innovation in the field of marine natural products, which in our view will lead to a new wave of drugs that flow into the market and pharmacies in the future.