Publications by authors named "Ravi Ojha"

Mammalian receptor-mediated endocytosis (RME) often involves at least one of three isoforms of the large GTPase dynamin (Dyn). Dyn pinches-off vesicles at the plasma membrane and mediates uptake of many viruses, although some viruses directly penetrate the plasma membrane. RME is classically interrogated by genetic and pharmacological interference, but this has been hampered by undesired effects.

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  • Photosynthetic organisms like cyanobacteria adjust their carbohydrate metabolism based on light conditions, switching between making and breaking down carbohydrates.
  • A study on the cyanobacterium Synechocystis sp. PCC 6803 revealed two iso-enzymes of phosphofructokinase (PFK) that uniquely use ADP instead of ATP and have different regulatory mechanisms affecting their activity in light and darkness.
  • This finding is significant as it shows a previously undocumented ADP dependence in the PFK-A enzyme family, suggesting a unique evolutionary adaptation in some cyanobacteria and a few related bacteria.
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6-mercaptopurine (6MP) is a chemotherapeuticdrug widely used for treating inflammatory bowel diseases and several cancers. Nevertheless, determining and monitoring its concentration in the human body is highly important because over or under-doses of 6MP can lead to critical health issues. In this paper, we have developed a turn-on fluorescent probe for the determination of the anticancer drug 6-mercaptopurine (6-MP) based on coordination complex [Nd (Anth) (HO)].

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Background: The neurological effects of the coronavirus disease of 2019 (COVID-19) raise concerns about potential long-term consequences, such as an increased risk of Alzheimer's disease (AD). Neuroinflammation and other AD-associated pathologies are also suggested to increase the risk of serious SARS-CoV-2 infection. Anosmia is a common neurological symptom reported in COVID-19 and in early AD.

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Emerging variants of concern of SARS-CoV-2 can significantly reduce the prophylactic and therapeutic efficacy of vaccines and neutralizing antibodies due to mutations in the viral genome. Targeting cell host factors required for infection provides a complementary strategy to overcome this problem since the host genome is less susceptible to variation during the life span of infection. The enzymatic activities of the endosomal PIKfyve phosphoinositide kinase and the serine protease TMPRSS2 are essential to meditate infection in two complementary viral entry pathways.

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Enteroviruses are one of the most abundant viruses causing mild to serious acute infections in humans and also contributing to chronic diseases like type 1 diabetes. Presently, there are no approved antiviral drugs against enteroviruses. Here, we studied the potency of vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAF mutant-related melanoma, as an antiviral against enteroviruses.

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2019 coronavirus disease (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition to respiratory illness, COVID-19 patients exhibit neurological symptoms lasting from weeks to months (long COVID). It is unclear whether these neurological manifestations are due to an infection of brain cells.

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  • * Researchers focused on targeting the viral entry process, specifically a crucial step called membrane fusion, using peptide inhibitors that disrupt the SARS-CoV-2 spike protein's structure.
  • * A newly designed peptide showed impressive effectiveness in inhibiting SARS-CoV-2 and its variants, being 100 times more potent than prior versions and suggesting new avenues for developing antiviral treatments.
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  • * Research using advanced tracking techniques reveals that an acidic environment (pH 6.2 to 6.8) is essential for the virus to effectively penetrate and release its genetic material into host cells, even after the initial cleavage events.
  • * The study highlights the importance of acidic conditions, which are found in places like the nasal cavity, for enhancing SARS-CoV-2 infection, particularly in cells that express TMPRSS2.
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  • Variants of SARS-CoV-2 are challenging the effectiveness of current COVID-19 vaccines and treatments, highlighting the need for alternative antivirals that can target less mutated viral processes, such as membrane fusion during viral entry.
  • Researchers discovered an extended HR2 peptide that significantly inhibits SARS-CoV-2 infection in various assays, demonstrating stronger performance compared to previous short peptides and maintaining effectiveness against major variants.
  • The findings suggest that targeting specific regions outside the conventional HR2 area could lead to the development of more potent peptide-based therapeutics for SARS-CoV-2 and potentially other related viruses.
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Unlabelled: SARS-CoV-2 cell entry starts with membrane attachment and ends with spike-protein (S) catalyzed membrane fusion depending on two cleavage steps, one usually by furin in producing cells and the second by TMPRSS2 on target cells. Endosomal cathepsins can carry out both. Using real-time 3D single virion tracking, we show fusion and genome penetration requires virion exposure to an acidic milieu of pH 6.

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The pharmacological arsenal against the COVID-19 pandemic is largely based on generic anti-inflammatory strategies or poorly scalable solutions. Moreover, as the ongoing vaccination campaign is rolling slower than wished, affordable and effective therapeutics are needed. To this end, there is increasing attention toward computational methods for drug repositioning and de novo drug design.

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Repurposing FDA-approved inhibitors able to prevent infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could provide a rapid path to establish new therapeutic options to mitigate the effects of coronavirus disease 2019 (COVID-19). Proteolytic cleavages of the spike (S) protein of SARS-CoV-2, mediated by the host cell proteases cathepsin and TMPRSS2, alone or in combination, are key early activation steps required for efficient infection. The PIKfyve kinase inhibitor apilimod interferes with late endosomal viral traffic and through an ill-defined mechanism prevents infection through late endosomes mediated by cathepsin.

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Repurposing FDA-approved inhibitors able to prevent infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could provide a rapid path to establish new therapeutic options to mitigate the effects of coronavirus disease 2019 (COVID-19). Proteolytic cleavages of the spike S protein of SARS-CoV-2, mediated by the host cell proteases cathepsin and TMPRSS2, alone or in combination, are key early activation steps required for efficient infection. The PIKfyve kinase inhibitor apilimod interferes with late endosomal viral traffic, and through an ill-defined mechanism prevents infection through late endosomes mediated by cathepsin.

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The causative agent of coronavirus disease 2019 (COVID-19) is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For many viruses, tissue tropism is determined by the availability of virus receptors and entry cofactors on the surface of host cells. In this study, we found that neuropilin-1 (NRP1), known to bind furin-cleaved substrates, significantly potentiates SARS-CoV-2 infectivity, an effect blocked by a monoclonal blocking antibody against NRP1.

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MoS quantum dots were hydrothermally synthesized and utilized for the formation and stabilization of a nanocomposite with silver nanoparticles (AgNPs) in a single step. This composite was characterized by transmission electron microscopy and zeta potential measurements. It is found that this nanohybrid can be stimulated by mercury(II) ion and then exhibits excellent oxidase mimicking activity.

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Two-dimensional (2D) inorganic layered materials when embedded in organic polymer matrix exhibit exotic properties that are grabbing contemporary attention for various applications. Here, nanosheet morphology of molybdenum disufide (MoS) synthesized via one-pot facile hydrothermal reaction are exfoliated in benign aqueous medium in the presence of indole to obtain a stable dispersion. These exfoliated nanosheets then act as host to template the controlled polymerization of indole.

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