Biology subjects

Dhar, P.

Publications and source records attributed to Dhar, P..

9 recordsLinked to original sources

bioRxiv2023

Curcumin alleviates Arsenic trioxide-induced behavioural impairment, oxidative damage & morphological alterations in striatal region of mice brain

Arsenic-induced neurotoxicity is well-documented in literature and reported to have dose-dependent damaging effects in the mice brain. Curcumin, a cost-effective plant polyphenol, safely demonstrates protective effects against arsenic-induced neurotoxicity by modifying oxidative stress, apoptosis, and neurochemistry in rodents brain. The present study determined the neuroprotective potential of curcumin (CUR) on adverse effects induced by arsenic trioxide (As2O3) in mice striatal region. Healthy adult male mice were chronically administered with varying concentrations of As2O3 (2, 4 & 8 mg/kg bw) alone and along with CUR (100 mg/kg bw) via oral route for 45 days. Towards the end of experimental period, the animals were subjected to behavioural paradigm including open field task, novel object recognition, rota-rod and morris water maze. Fresh striatal tissues were collected from the animals on day 46 for biochemical analysis such as MDA, GPx and GSH. While perfusion fixed brains were processed for morphological observations. Behavioural study showed an apparent decrease in certain cognitive functions (learning and memory) and locomotor activity in mice exposed to As2O3 compared to controls. Simultaneous treatment of As2O3 (2, 4 & 8 mg/kg bw) and curcumin (100 mg/kg bw) alleviated the As-induced locomotor and cognitive deficits. As2O3 alone exposure also exhibited a significant increase in oxidative stress marker (MDA) and decrease in antioxidant enzyme levels (GPx, GSH). Morphological alterations were noted in mice subjected to elevated doses of As2O3 (4 & 8 mg/kg bw). However, these changes were reversed in mice who received As2O3 + CUR co-treatment. Together, our findings provide preliminary evidence that curcumin protects mice striatal region from As2O3-induced behavioral, biochemical and morphological alterations.

pharmacology and toxicology↗

bioRxiv2023

Harnessing Escherichia coli Dark Genome to Produce Anti-Alzheimer Peptides

Alzheimers disease (AD) is characterized by progressive neurodegeneration. The critical molecular trigger is believed to be the accumulation of A{beta} neurotoxic oligomers. Given the proteolytic processing of Amyloid Precursor Protein (APP) by {beta}-secretase (beta-site APP cleaving enzyme 1, BACE1) as the key step in the building up of A{beta} oligomers, BACE inhibitors come with therapeutic prospects of preventing or delaying the onset of Alzheimers. To find inhibitory peptides against BACE1, a library of dark peptides was constructed from 4400 intergenic DNA sequences of Escherichia coli. The sequence level analysis was followed by protein structure predictions, molecular docking, and simulation. Based on bioinformatics analysis, 5 potential peptides were screened for experimental validation. Out of these two peptides were identified as lead molecules based on BACE1 inhibitory activity, followed by FRET inhibitory assay, western blot, and RT-PCR. An 86.7 % drop in BACE1 level was observed in the presence of the ECOI2 peptide. Though encouraging results were obtained from in-silico and in-vitro studies, more work is required to study the efficacy of these peptides in suitable animal models.

synthetic biology↗

bioRxiv2023

Therapeutic immunization with a whole cell vaccine reduces pneumococcal nasopharyngeal density, shedding, and middle ear infection in mice

Pneumococcal Conjugate Vaccines (PCVs) have substantially reduced the burden of disease caused by Streptococcus pneumoniae (the pneumococcus). However, protection is limited to vaccine serotypes, and when administered to children who are colonized with pneumococci at the time of vaccination, immune responses to the vaccine are blunted. Here, we investigate the potential of a killed whole cell pneumococcal vaccine (WCV) to reduce existing pneumococcal carriage and mucosal disease when given therapeutically to infant mice colonized with pneumococci. We show that a single dose of WCV reduced pneumococcal carriage density in an antibody-dependent manner. Therapeutic vaccination induced robust immune responses to pneumococcal surface antigens CbpA, PspA (family 1) and PiaA. In a co-infection model of otitis media, a single dose of WCV reduced pneumococcal middle ear infection. Lastly, in a two-dose model, therapeutic administration of WCV reduced nasal shedding of pneumococci. Taken together, our data demonstrate that WCV administered in colonized mice reduced pneumococcal density in the nasopharynx and the middle ear, and decreased shedding. A vaccine with similar properties in children would be beneficial in low and middle-income settings where pneumococcal carriage is high. ImportanceAlthough typically asymptomatic, pneumococcal carriage plays an essential role in transmission and the development of disease. Pneumococcal Conjugate Vaccines (PCVs) have reduced the burden of pneumococcal disease worldwide. However, their use has increased carriage and disease caused by non-vaccine serotypes, prompting investigations into serotype-independent pneumococcal vaccines. An additional limitation of PCVs is immune hypo-responsiveness to vaccines in children carrying pneumococci at the time of vaccination. Therefore, there is great interest in next generation vaccines such as whole cell vaccines. In this study we investigate a pneumococcal whole cell vaccine (WCV) for it effect on carriage in mice that are already colonized at the time of vaccination. We show that this therapeutic vaccination of mice can reduce pneumococcal carriage density, shedding and infection of the middle ear. Our study suggests that WCV could be beneficial in high burden settings where carriage at the time of vaccination is more common.

microbiology↗

bioRxiv2022

A mechanistic insight into Nigella sativa mediated anticancer effect on breast cancer through regulation of various miRNAs: An in vitro & in vivo study

BackgroundCancer continues to threat the mortal alongside scientific community with its burgeoning grasp. Although efforts have been directed to tame cancer by radiotherapy, photodynamic therapy, chemotherapy it came at a cost of fatal side effects. PurposePlant derived bioactive compounds carries an inevitable advantage of being safer, bioavailable & less toxic compared to contemporary chemotherapeutics. This study analyzed anti-cancerous potential of volatile oil, extracted from Nigella sativa, in-vitro against MDA-MB-231, MCF-7 & in-vivo on tumor growth in mice after successful oral administration. Study DesignOur strategic approach employed solvent extraction of black seed oil (BSO) to highlight orchestrated use of its potent integrants - TQ, Carvacrol & TA which in modest amounts show anti-cancerous properties compared to their individual treatment. We attempted to show this cost effective, safe & bioavailable form of dealing with the atrocities of breast cancer by means of MTT, Apoptotic, Western Blot Assays besides Transwell & Wound healing Assay. Reduction in the solid tumour in-vivo & near normalcy restoration of tissue section architecture from the BSO treated tumour sets are indicative of the better anti-tumorigenic potential of BSO. MethodsBSOs Solvent extraction was performed followed by its characterization. MTT aided cytotoxicity study of BSO alongside major components in PBMC & cancer cells while its efficacy was presented by flow cytometric ROS analysis, cell cycle arrest & apoptosis assessment. Anti-migratory potential evaluated by Wound Healing, Transwell Migration & Western Blot while the expression study of a wide range of proteins, miRNAs & the in-vivo studies undertaken climaxed the confirmation of the anti-cancerous potential of BSO. ResultsComparatively reduced concentrations of TQ, TA & Carvacrol in BSO played a synergistic role to enhance apoptotic potential via Caspase 7 & 9, through enhanced ROS & expression of apoptotic family of proteins, miRNAs besides uplifting the anti-migratory perspective by effectively enhancing E-cad & downregulating lamellipodia, filopodia assembly & MMPs in MCF-7 & MDA-MB-231. Similar observations in-vivo outlined the therapeutic potential of BSO. ConclusionThis study culminates isolation & processing of BSO in a simplified procedure, thereby aiming at a more lucrative paradigm to be accepted in contemporary phytomedicine research.

cancer biology↗

bioRxiv2020

Discovery of tREP-18, a novel class of tRNA encoded peptide with potent leishmanicidal activity

In the post genomic era, tRNA-derived fragments have emerged as a new class of non-coding gene regulators, those play crucial roles both at the transcriptional and translational levels, in different cellular biogenesis. However, none of the studies has ever asked whether tRNAs can also be translated into peptides with any biological significance. Thus, we present a novel hypothesis which suggested that; design and synthesis of tRNA-derived peptides from prokaryotic genome can be exploited for developing unique chemotherapeutics against neglected tropical diseases, like Visceral leishmaniasis (VL) and its aggressive form known as post kalazar dermal leishmaniasis (PKDL). To achieve this aim, we have used a novel system biology-based strategy, which involved; i) mining of unique tRNAs from E. coli genome and their translation into peptide in silico, ii) designing of theoretical 3D models to evaluate their stability, iii) prediction of their biological activity by screening against anti-parasitic database to filter the lead peptide. Based on this strategy, a unique tRNA-derived peptide (tREP-18) was selected, chemically synthesized, and used in vitro for elucidating its therapeutic significance against L. donovani, a causative agent of VL and PKDL. Our findings demonstrated that, tREP-18 can impose high level toxicity to L. donovani promastigotes, by disrupting the ultrastructural cellular architect, destabilizing the mitochondrial membrane potential ({Delta}{Psi}m), thus leading to drastic reduction in cell viability and proliferation. It also imparted high level of toxicity to BS12 a clinical isolate of PKDL. Conceivably, we for the first time reports a novel tRNA-derived peptide "tREP18" with excellent anti-leishmanial property, which can be further utilized for developing it as antileishmanial drug. One Sentence SummaryHere we report a novel first-in-class tRNA encoded peptide and its super anti-leishmanial characteristics.

synthetic biology↗

bioRxiv2020

In vitro and in silico analyses of the angiotensin-I converting enzyme inhibitory activity of peptides identified from Bellamya bengalensis protein hydrolysates

The study focuses on identification of ACE-inhibitory peptides from the proteolytic digests of muscle protein of Bellamya bengalensis and its underlying mechanism. 120 min Alcalase-hydrolysates were ultrafiltered to isolate the small peptide fraction (<3kDa) and in vitro ACE-inhibitory activity was analyzed. The IC50 value of the 120 min hydrolysate ultafiltered fraction was found to be 86.74 {+/-} 0.575 {micro}g/mL, while the IC50 of Lisinopril is 0.31 {+/-} 0.07 {micro}g/mL. This fraction was assessed in MALDI-ToF mass-spectrometer and five peptides were sequenced via de novo sequencing. The ACE-inhibitory potential of the peptides have a positive correlation with the hydrophobicity of the amino acids. Synthetic analogue of the peptide (IC50 value 8.52 {+/-} 0.779 {micro}g/mL) was used to understand the thermodynamics of the inhibition by checking the binding affinity of the peptide to ACE by Isothermal titration calorimetry compared with lisinopril, and further substantiated by in silico site specific molecular docking study.

biochemistry↗

bioRxiv2020

Preliminary Evidence of the role of estrogen and tamoxifen-induced regulation of complement proteins in rat hippocampus

Effects of Estrogen (E2) is widespread in the human body; still, an unresolved paradox. Neurodegeneration and neuroinflammation are inherently associated with age progression, debilitating by hormone deprivation, especially in female. Senescent cells accumulate with age and promote tissue deterioration in the body system. Neurodegenerative diseases drive a healthy life towards to morbidity and feebleness; despite the different etiology, uncontrolled inflammation is one of the significant causals factors. We here used post-menopausal model (ovariectomized female rat), E2 replenishment therapy reduces the expression of inflammatory mediators, such as complement proteins (C3, C1q, and C3aR) in these animals. E2 therapy could limit the ovariectomy-induced increase of inflammatory events in brain regions such as the hippocampus. Also, the duration of hormone deprivation could be a determinant for the intensity of the anti-inflammatory actions of estrogen. On the whole, considerable evidence, including that from the present study supports the view that complement biosynthesis, which plays a significant role in phagocytosis of cellular debris and synaptic pruning of postnatal neural circuits goes uncontrolled and could be the inducing factor for enhanced neurodegeneration following hormone deprivation.

neuroscience↗

bioRxiv2019

Viscoelastic properties of ECM-rich embryonic microenvironments

The material properties of tissues and their mechanical state is an important factor during development, disease, regenerative medicine and tissue engineering. Here we describe a microrheological measurement technique utilizing aggregates of microinjected ferromagnetic nickel particles to probe the viscoelastic properties of embryonic tissues. Quail embryos were cultured in a plastic incubator chamber located at the center of two pairs of crossed electromagnets. We estimate the Youngs modulus of the ECM-rich region separating the mesoderm and endoderm in Hamburger Hamilton stage 6-10 quail embryos as 300{+/-}100 Pa. We found a pronounced viscoelastic behavior consistent with a Zener (standard generalized solid) model. The viscoelastic response is about 45% of the total response, with a characteristic relaxation time of 1.3 sec.

developmental biology↗

bioRxiv2017

HYPO: A database of hypothetical human proteins

All annotated genes were once hypothetical or uncharacterized. Keeping this as an epilogue, we have enhanced our former database of hypothetical proteins (HP) in human (HypoDB) with added annotation, application programming interfaces and descriptive features. The database hosts 1000+ manually curated records of the known unknown regions in the human genome. The new updated version of HypoDB with functionalities (Blast, Match) is freely accessible at http://www.bioclues.org/hypo2.

bioinformatics↗