Publications by authors named "S K Shrivastava"

1,189 Publications

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Cholesterol-Dependent Dynamics of the Serotonin Receptor Utilizing Single Particle Tracking: Analysis of Diffusion Modes.

J Phys Chem B 2022 Aug 16. Epub 2022 Aug 16.

CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.

G protein-coupled receptors (GPCRs) are signaling hubs in cell membranes that regulate a wide range of physiological processes and are popular drug targets. Serotonin receptors are important members of the GPCR family and are implicated in neuropsychiatric disorders. Cholesterol is a key constituent of higher eukaryotic membranes and is believed to contribute to the segregated distribution of membrane constituents into domains. To explore the role of cholesterol in lateral dynamics of GPCRs, we utilized single particle tracking (SPT) to monitor diffusion of serotonin receptors under acute and chronic cholesterol-depleted conditions. Our results show that the short-term diffusion coefficient of the receptor decreases upon cholesterol depletion, irrespective of the method of cholesterol depletion. Analysis of SPT trajectories revealed that relative populations of receptors undergoing various modes of diffusion change upon cholesterol depletion. Notably, in cholesterol-depleted cells, we observed an increase in the confined population of the receptor accompanied by a reduction in diffusion coefficient for chronic cholesterol depletion. These results are supported by our recent work and present observations that show polymerization of G-actin in response to chronic cholesterol depletion. Taken together, our results bring out the interdependence of cholesterol and actin cytoskeleton in regulating diffusion of GPCRs in membranes.
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http://dx.doi.org/10.1021/acs.jpcb.2c03941DOI Listing
August 2022

Culture-Free Quantification of Bacteria Using Digital Fluorescence Imaging in a Tunable Magnetic Capturing Cartridge for Onsite Food Testing.

ACS Sens 2022 Aug 5. Epub 2022 Aug 5.

School of Advanced Materials Science & Engineering, Sungkyunkwan University, Gyeonggi-do, Suwon 16419, Korea.

Accurate, onsite detection of pathogenic bacteria from food matrices is required to rapidly respond to pathogen outbreaks. However, accurately detecting whole-cell bacteria in large sample volumes without an enrichment step remains a challenge. Therefore, bacterial samples must be concentrated, identified, and quantified. We developed a tunable magnetic capturing cartridge (TMCC) and combined it with a portable digital fluorescence reader for quick, onsite, quantitative detection of . The TMCC platform integrates an absorption pad impregnated with water-soluble polyvinyl alcohol (PVA) with an injection-molded polycarbonate (PC) plate that has a hard magnet on its back and an acrylonitrile-butadiene-styrene case. An -specific antibody conjugated with magnetic nanoparticles was used to concentrate bacteria from a large-volume sample and capture bacteria within the TMCC. The retention time for capturing bacteria on the TMCC was adjusted by controlling the concentration and volume of the PVA solution. Concentrated bacterial samples bound to target-specific aptamer probes conjugated with quantum dots were loaded into the TMCC for a controlled time, followed by attachment of the bacteria to the PC plate and removal of unbound aptamer probes with wash buffer. The captured bacteria were quantified using a digital fluorescence reader equipped with an embedded program that automatically counts fluorescently tagged bacteria. The bacterial count made using the TMCC was comparable to a standard plate count ( = 0.9898), with assay sensitivity and specificity of 94.3 and 100%, respectively.
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http://dx.doi.org/10.1021/acssensors.2c00372DOI Listing
August 2022

Perspectives on the microorganism of extreme environments and their applications.

Curr Res Microb Sci 2022 21;3:100134. Epub 2022 Apr 21.

Department of Zoology, Hindu College, University of Delhi, Delhi-110007, India.

Extremophiles are organisms that can survive and thrive in conditions termed as "extreme" by human beings. Conventional methods cannot be applied under extreme conditions like temperature and pH fluctuations, high salinity, etc. for a variety of reasons. Extremophiles can function and are adapted to thrive in these environments and are sustainable, cheaper, and efficient, therefore, they serve as better alternatives to the traditional methods. They adapt to these environments with biochemical and physiological changes and produce products like extremolytes, extremozymes, biosurfactants, etc., which are found to be useful in a wide range of industries like sustainable agriculture, food, cosmetics, and pharmaceuticals. These products also play a crucial role in bioremediation, production of biofuels, biorefinery, and astrobiology. This review paper comprehensively lists out the current applications of extremophiles and their products in various industries and explores the prospects of the same. They help us understand the underlying basis of biological mechanisms exploring the boundaries of life and thus help us understand the origin and evolution of life on Earth. This helps us in the research for extra-terrestrial life and space exploration. The structure and biochemical properties of extremophiles along with any possible long-term effects of their applications need to be investigated further.
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http://dx.doi.org/10.1016/j.crmicr.2022.100134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9325743PMC
April 2022

Serial bone density changes in women undergoing pelvic (chemo) radiation: Results from PARCER trial.

Int J Radiat Oncol Biol Phys 2022 Jul 20. Epub 2022 Jul 20.

Department of Radiation Oncology, Tata Memorial Hospital, Tata Memorial Centre, Homi Bhabha National Institute, Parel, Mumbai, Maharashtra, India.

Purpose: Pelvic irradiation leads to substantial dose to the pelvic girdle. However, bone density loss as a function of radiotherapy (RT) dose and time has not been investigated. This study was undertaken to evaluate such a dose-response relationship.

Methods And Materials: Women undergoing pelvic radiotherapy for cervix cancer within a phase III trial were included. The study necessitated 2 CT imaging sets acquired atleast 12 months apart in patients with no evidence of relapse. All images were transferred to the treatment planning system to determine radiation dose and Hounsfield Unit (HU). Across the entire lumbopelvic region (Lumbar 1-5 (L1-5) vertebra, pubic symphysis, femur, acetabulum, greater trochanter, and anterior-superior iliac spine) multiple regions were defined to measure RT dose and HU. Bone health was categorized as normal if HU>130, osteopenic at 110-130 HU and osteoporotic <110HU at baseline and follow up. Univariate analysis was performed to test impact of various factors on HU. Further interaction between radiotherapy dose, time and HU was assessed using linear mixed model.

Results: Overall, 132/300 patients were eligible. The median age was 49 (42-56) years. With a prescription dose of 50Gy, L1-2 vertebra received median dose of 1.2Gy and 4Gy respectively, L3-5 received 10-50 Gy. At 24 months, median HU loss at L4-5 was 45 HU (IQR: 34-77HU). Out of the 132 patients, at baseline 96% had normal bone health. However, at the last follow up 3% of patients had normal bone health and 12% developed osteopenia and 85% developed osteoporosis (p-value <0.001). No patient or treatment related factors predicted for HU loss on univariate analysis. HU loss >60-70 was observed at >45 Gy at L5 vertebrae (60-70 HU, p<0.02) and >15 Gy at L4 vertebra (33HU and p value 0.04).

Conclusions: Dose-response relationship is observed between radiation dose and bone mineral density loss. Prospective studies are needed to corroborate these observations and design future interventions.
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http://dx.doi.org/10.1016/j.ijrobp.2022.07.008DOI Listing
July 2022

Dissipative particle dynamics simulation study on ATRP-brush modification of variably shaped surfaces and biopolymer adsorption.

Phys Chem Chem Phys 2022 Aug 3;24(30):17986-18003. Epub 2022 Aug 3.

Department of Physics, Indian Institute of Technology (BHU), Varanasi-221005, Uttar Pradesh, India.

We present a dissipative particle dynamics (DPD) simulation study on the surface modification of initiator embedded microparticles (MPs) of different shapes atom transfer radical polymerization (ATRP) brush growth. The surface-initiated ATRP-brush growth leads to the formation of a more globular MP shape. We perform the comparative analysis of ATRP-brush growth on three different forms of particle surfaces: cup surface, spherical surface, and flat surface (rectangular/disk-shaped). First, we establish the chemical kinetics of the brush growth: the monomer conversion and the reaction rates. Next, we discuss the structural changes (shape-modification) of brush-modified surfaces by computing the radial distribution function, spatial density distribution, radius of gyration, hydrodynamic radius, and shape factor. The polymer brush-modified particles are well known as the carrier materials for enzyme immobilization. Finally, we study the biopolymer adsorption on ATRP-brush modified particles in a compatible solution. In particular, we explore the effect of ATRP-brush length, biopolymer chain length, and concentration on the adsorption process. Our results illustrate the enhanced biopolymer adsorption with increased brush length, initiator concentration, and biopolymer concentration. Most importantly, when adsorption reaches saturation, the flat surface loads more biopolymers than the other two surfaces. The experimental results verified the same, considering the disk-shaped flat surface particles, cup-shaped particles, and spherical particles.
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http://dx.doi.org/10.1039/d2cp01749kDOI Listing
August 2022
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