Browsing by Author "Kumar, S"

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    Assessment of risk conferred by coding and regulatory variations of TMPRSS2 and CD26 in susceptibility to SARS-CoV-2 infection in human
    (Springer, 2020) Senapati, S; Kumar, S; Singh, A.K; Banerjee, P; Bhagavatula, S.
    At present, more than 200 countries and territories are directly affected by the coronavirus disease-19 (COVID-19) pandemic. Incidence and case fatality rate are significantly higher among elderly individuals (age > 60 years), type 2 diabetes and hypertension patients. Cellular receptor ACE2, serine protease TMPRSS2 and exopeptidase CD26 (also known as DPP4) are the three membrane bound proteins potentially implicated in SARS-CoV-2 infection. We hypothesised that common variants from TMPRSS2 and CD26 may play critical role in infection susceptibility of predisposed population or group of individuals. Coding (missense) and regulatory variants from TMPRSS2 and CD26 were studied across 26 global populations. Two missense and five regulatory SNPs were identified to have differential allelic frequency. Significant linkage disequilibrium (LD) signature was observed in different populations. Modelled protein?protein interaction (PPI) predicted strong molecular interaction between these two receptors and SARS-CoV-2 spike protein (S1 domain). However, two missense SNPs, rs12329760 (TMPRSS2) and rs1129599 (CD26), were not found to be involved physically in the said interaction. Four regulatory variants (rs112657409, rs11910678, rs77675406 and rs713400) from TMPRSS2 were found to influence the expression of TMPRSS2 and pathologically relevant MX1. rs13015258 a 5? UTR variant from CD26 have significant role in regulation of expression of key regulatory genes that could be involved in SARS-CoV-2 internalization. Overexpression of CD26 through epigenetic modification at rs13015258-C allele was found critical and could explain the higher SARS-CoV-2 infected fatality rate among type 2 diabetes. 2020, Indian Academy of Sciences.
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    Chitin and chitosan-based support materials for enzyme immobilization and biotechnological applications
    (Springer, 2020) Verma, M.L; Kumar, S; Das, A; Randhawa, J.S; Chamundeeswari, M.
    Enzymes of industrial importance are primarily employed for biotechnological applications. However, high-cost and instability issues of purified enzymes hamper their usage. Multiple reuses rather than the single use is more�cost-effective. A�robuster bioprocess is feasible by enzyme immobilization. Performance of immobilized enzymes depends on the nature of support materials. Chitin and its derivatives-based supports offer stability and cost-effective bioprocessing. Chitosan is�biocompatible, biodegradable, non-toxic and has�multiple functional groups. A variety of supports such as chitosan, chitosan film, chitosan nanoparticle and chitosan nanocomposite are employed for enzyme immobilization. Chitosan bound enzymes, as compared to free enzymes, have improved the�biocatalytic performances due to exceptionally high operational stability and reusability. Here we review enzymes immobilized on chitin/chitosan supporting materials with�applications ranging from agriculture to drug delivery. � 2019, Springer Nature Switzerland AG.
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    Indo-US Convergence of Agenda in the new Indo-Pacific Regional Security Architecture
    (Sage Publications India Pvt. Ltd, 2020) Kumar, S; Verma, S.S; Shah, S.H.
    Strengthened Indo-US proximity has become a notable factor in the regional security architecture of the Indo-Pacific region, and also it raises ongoing concerns about its robustness. This article analyses the geostrategic, geoeconomic, security-related and defence-connected Indo-US relations in the region over the last two decades, highlighting the growing multidimensional convergence of US and Indian interests in the Indo-Pacific regional security architecture. In the final part, this article also sketches the future implications of Indo-US proximity and seeks to identify potential risks. -2020 SAGE Publications.
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    Inflammasome activation and regulation during Helicobacter pylori pathogenesis
    (Elsevier, 2018) Kumar, S; Dhiman, Monisha
    Helicobacter pylori is a leading cause of gastric cancer worldwide, its type four secretary toxin CagA is cited to be primarily responsible for it. Other virulence factors such as urease, VacA, HopQ, BabA and SabA are responsible for bacterial survival in acidic environment, adherence and cellular damage but its molecular mechanism is not completely understood. A number of pathogens including bacteria, fungi and virus are involved in the regulation of cellular machinery of inflammasome. Inflammasomes are multimeric protein complexes formed after external stimuli such as PAMPs/DAMPs or salt crystals and activates cellular caspases causes inflammation via pro-inflammatory cytokines. Virulence factors associated with microbial pathogens causes’ cellular damage through damaging mitochondria, rupturing lysosome, producing endoplasmic stress and dysregulation of cellular ions balance. These cellular dysfunctioning leads to oxidative stress, cathepsin B production, nuclear and mitochondrial DNA damage which activates inflammasome machinery, pro-inflammatory cytokine release and cellular death known as pyroptosis. The mechanism of inflammasome induction by H. pylori is not studied extensively and very few virulence factors such as UreB, CagA, FlaA and VacA and their role in inflammasomes is established. This review elaborates the mechanism of inflammasomes regulation and elucidates the pathways through which H. pylori regulates inflammasome activation.