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result(s) for
"Kumar, Ambuj"
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Use of Long Term Molecular Dynamics Simulation in Predicting Cancer Associated SNPs
2014
Computational prediction of cancer associated SNPs from the large pool of SNP dataset is now being used as a tool for detecting the probable oncogenes, which are further examined in the wet lab experiments. The lack in prediction accuracy has been a major hurdle in relying on the computational results obtained by implementing multiple tools, platforms and algorithms for cancer associated SNP prediction. Our result obtained from the initial computational compilations suggests the strong chance of Aurora-A G325W mutation (rs11539196) to cause hepatocellular carcinoma. The implementation of molecular dynamics simulation (MDS) approaches has significantly aided in raising the prediction accuracy of these results, but measuring the difference in the convergence time of mutant protein structures has been a challenging task while setting the simulation timescale. The convergence time of most of the protein structures may vary from 10 ns to 100 ns or more, depending upon its size. Thus, in this work we have implemented 200 ns of MDS to aid the final results obtained from computational SNP prediction technique. The MDS results have significantly explained the atomic alteration related with the mutant protein and are useful in elaborating the change in structural conformations coupled with the computationally predicted cancer associated mutation. With further advancements in the computational techniques, it will become much easier to predict such mutations with higher accuracy level.
Journal Article
A mechanism by which gut microbiota elevates permeability and inflammation in obese/diabetic mice and human gut
2023
ObjectiveAmple evidence exists for the role of abnormal gut microbiota composition and increased gut permeability (‘leaky gut’) in chronic inflammation that commonly co-occurs in the gut in both obesity and diabetes, yet the detailed mechanisms involved in this process have remained elusive.DesignIn this study, we substantiate the causal role of the gut microbiota by use of faecal conditioned media along with faecal microbiota transplantation. Using untargeted and comprehensive approaches, we discovered the mechanism by which the obese microbiota instigates gut permeability, inflammation and abnormalities in glucose metabolism.ResultsWe demonstrated that the reduced capacity of the microbiota from both obese mice and humans to metabolise ethanolamine results in ethanolamine accumulation in the gut, accounting for induction of intestinal permeability. Elevated ethanolamine increased the expression of microRNA-miR-101a-3p by enhancing ARID3a binding on the miR promoter. Increased miR-101a-3p decreased the stability of zona occludens-1 (Zo1) mRNA, which in turn, weakened intestinal barriers and induced gut permeability, inflammation and abnormalities in glucose metabolism. Importantly, restoring ethanolamine-metabolising activity in gut microbiota using a novel probiotic therapy reduced elevated gut permeability, inflammation and abnormalities in glucose metabolism by correcting the ARID3a/miR-101a/Zo1 axis.ConclusionOverall, we discovered that the reduced capacity of obese microbiota to metabolise ethanolamine instigates gut permeability, inflammation and glucose metabolic dysfunctions, and restoring ethanolamine-metabolising capacity by a novel probiotic therapy reverses these abnormalities.Trial registration number NCT02869659 and NCT03269032.
Journal Article
Timed Barium Swallow: Diagnostic Role and Predictive Value in Untreated Achalasia, Esophagogastric Junction Outflow Obstruction, and Non-Achalasia Dysphagia
2018
Objectives:Timed barium swallow (TBS) assesses esophageal emptying in patients with achalasia and is considered the standard workup for patients with dysphagia. Our aim was to determine the usefulness of TBS in differentiating patients with achalasia (type 1-3), esophagogastric junction outflow obstruction (EGJOO), and non-achalasia dysphagia.Methods:We performed a retrospective cohort study including consecutive patients who underwent TBS evaluation between May 2013 and September 2015. Patients were separated into untreated achalasia (n=117), EGJOO (n=46), and non-achalasia (n=146) groups. Diagnosis of achalasia/EGJOO was based on high-resolution manometry using Chicago Classification. Receiver operating characteristic (ROC) curve analysis was performed to determine the accuracy of TBS (barium height at 1 and 5 min and tablet retention) in identifying achalasia vs. EGJOO and non-achalasia.Results:Barium column height of 5 cm at 1 min showed a sensitivity of 94% and specificity of 71% and barium column height of 2 cm at 5 min showed a sensitivity of 85% and specificity of 86% in differentiating untreated achalasia from EGJOO and non-achalasia. Combined liquid barium and tablet increases diagnostic yield from 79.5 to 100% in untreated achalasia patients and from 48.9 to 60% in EGJOO patients.Conclusions:TBS is a simple and useful test in differentiating untreated achalasia, EGJOO, and non-achalasia dysphagia. We propose that barium height >2 cm at 5 min be used as cutoff point for identifying achalasia. Combination of liquid barium and tablet increased the diagnostic yield of TBS in achalasia and EGJOO. Retention of barium tablet alone suggests functional/anatomic obstruction at the esophagogastric junction.
Journal Article
Cancer Associated E17K Mutation Causes Rapid Conformational Drift in AKT1 Pleckstrin Homology (PH) Domain
2013
AKT1 (v-akt murine thymoma viral oncogene homologue 1) kinase is one of the most frequently activated proliferated and survival pathway of cancer. Recently it has been shown that E17K mutation in the Pleckstrin Homology (PH) domain of AKT1 protein leads to cancer by amplifying the phosphorylation and membrane localization of protein. The mutant has shown resistance to AKT1/2 inhibitor VIII drug molecule. In this study we have demonstrated the detailed structural and molecular consequences associated with the activity regulation of mutant protein.
The docking score exhibited significant loss in the interaction affinity to AKT1/2 inhibitor VIII drug molecule. Furthermore, the molecular dynamics simulation studies presented an evidence of rapid conformational drift observed in mutant structure.
There was no stability loss in mutant as compared to native structure and the major cation-π interactions were also shown to be retained. Moreover, the active residues involved in membrane localization of protein exhibited significant rise in NHbonds formation in mutant. The rise in NHbond formation in active residues accounts for the 4-fold increase in the membrane localization potential of protein.
The overall result suggested that, although the mutation did not induce any stability loss in structure, the associated pathological consequences might have occurred due to the rapid conformational drifts observed in the mutant AKT1 PH domain.
The methodology implemented and the results obtained in this work will facilitate in determining the core molecular mechanisms of cancer-associated mutations and in designing their potential drug inhibitors.
Journal Article
Yukawa–Casimir Wormholes in f(Q) Gravity
2023
Casimir energy is always suggested as a possible source to create a traversable wormhole. It is also used to demonstrate the existence of negative energy, which can be created in a lab. To generalize this idea, Yukawa modification of a Casimir source has been considered in Remo Garattini (Eur. Phys. J. C 81 no.9, 824, 2021). In this work, we explore the Yukawa–Casimir wormholes in symmetric teleparallel gravity. We have taken four different forms of f(Q) to obtain wormhole solutions powered by the original Casimir energy source and Yukawa modification of the Casimir energy source. In power law form f(Q)=αQ2+β and quadratic form f(Q)=αQ2+βQ+γ, where α,β,γ are constants and Q is non-metricity scalar, we analyze that wormhole throat is filled with non-exotic matter. We find self-sustained traversable wormholes in the Casimir source where null energy conditions are violated in all specific forms of f(Q), while after Yukawa modification, it is observed that violation of null energy conditions is restricted to some regions in the vicinity of the throat.
Journal Article
Efficacy and Safety of Prophylactic Vaccines against Cervical HPV Infection and Diseases among Women: A Systematic Review & Meta-Analysis
2011
Background
We conducted a systematic review and meta-analysis to assess efficacy and safety of prophylactic HPV vaccines against cervical cancer precursor events in women.
Methods
Randomized-controlled trials of HPV vaccines were identified from MEDLINE, Cochrane Central Register of Controlled Trials, conference abstracts and references of identified studies, and assessed by two independent reviewers. Efficacy data were synthesized using fixed-effect models, and evaluated for heterogeneity using I
2
statistic.
Results
Seven unique trials enrolling 44,142 females were included. The fixed-effect Relative Risk (RR) and 95% confidence intervals were 0.04 (0.01-0.11) and 0.10 (0.03-0.38) for HPV-16 and HPV 18-related CIN2+ in the per-protocol populations (PPP). The corresponding RR was 0.47 (0.36-0.61) and 0.16 (0.08-0.34) in the intention-to-treat populations (ITT). Efficacy against CIN1+ was similar in scale in favor of vaccine. Overall vaccines were highly efficacious against 6-month persistent infection with HPV 16 and 18, both in the PPP cohort (RR: 0.06 [0.04-0.09] and 0.05 [0.03-0.09], respectively), and the ITT cohorts (RR: 0.15 [0.10-0.23] and 0.24 [0.14-0.42], respectively). There was limited prophylactic effect against CIN2+ and 6-month persistent infections associated with non-vaccine oncogenic HPV types. The risk of serious adverse events (RR: 1.00, 0.91-1.09) or vaccine-related serious adverse events (RR: 1.82; 0.79-4.20) did not differ significantly between vaccine and control groups. Data on abnormal pregnancy outcomes were underreported.
Conclusions
Prophylactic HPV vaccines are safe, well tolerated, and highly efficacious in preventing persistent infections and cervical diseases associated with vaccine-HPV types among young females. However, long-term efficacy and safety needs to be addressed in future trials.
Journal Article
Endothelial glycocalyx-associated molecules as potential serological markers for sepsis-associated encephalopathy: A systematic review and meta-analysis
2023
Sepsis-associated encephalopathy (SAE) is characterized by a diffuse cerebral dysfunction that accompanies sepsis in the absence of direct central nervous system infection. The endothelial glycocalyx is a dynamic mesh containing heparan sulfate linked to proteoglycans and glycoproteins, including selectins and vascular/intercellular adhesion molecules (V/I-CAMs), which protects the endothelium while mediating mechano-signal transduction between the blood and vascular wall. During severe inflammatory states, components of the glycocalyx are shed into the circulation and can be detected in soluble forms. Currently, SAE remains a diagnosis of exclusion and limited information is available on the utility of glycocalyx-associated molecules as biomarkers for SAE. We set out to synthesize all available evidence on the association between circulating molecules released from the endothelial glycocalyx surface during sepsis and sepsis-associated encephalopathy.
MEDLINE (PubMed) and EMBASE were searched since inception until May 2, 2022 to identify eligible studies. Any comparative observational study: i) evaluating the association between sepsis and cognitive decline and ii) providing information on level of circulating glycocalyx-associated molecules was eligible for inclusion.
Four case-control studies with 160 patients met the inclusion criteria. Meta-analysis of biomarkers ICAM-1 (SMD 0.41; 95% CI 0.05-0.76; p = 0.03; I2 = 50%) and VCAM-1 (SMD 0.55; 95% CI 0.12-0.98; p = 0.01; I2 = 82%) revealed higher pooled mean concentration in patients with SAE compared to the patients with sepsis alone. Single studies reported elevated levels of P-selectin (MD 0.80; 95% CI -17.77-19.37), E-selectin (MD 96.40; 95% Cl 37.90-154.90), heparan sulfate NS2S (MD 19.41; 95% CI 13.37-25.46), and heparan sulfate NS+NS2S+NS6S (MD 67.00; 95% CI 31.00-103.00) in patients with SAE compared to the patients with sepsis alone.
Plasma glycocalyx-associated molecules are elevated in SAE and may be useful for early identification of cognitive decline in sepsis patients.
Journal Article
Molecular Dynamic Simulation Reveals Damaging Impact of RAC1 F28L Mutation in the Switch I Region
by
Purohit, Rituraj
,
Rajendran, Vidya
,
Kumar, Ambuj
in
Amino Acid Substitution
,
Bioinformatics
,
Botulinum toxin
2013
Ras-related C3 botulinum toxin substrate 1 (RAC1) is a plasma membrane-associated small GTPase which cycles between the active GTP-bound and inactive GDP-bound states. There is wide range of evidences indicating its active participation in inducing cancer-associated phenotypes. RAC1 F28L mutation (RAC(F28L)) is a fast recycling mutation which has been implicated in several cancer associated cases. In this work we have performed molecular docking and molecular dynamics simulation (~0.3 μs) to investigate the conformational changes occurring in the mutant protein. The RMSD, RMSF and NHbonds results strongly suggested that the loss of native conformation in the Switch I region in RAC1 mutant protein could be the reason behind its oncogenic transformation. The overall results suggested that the mutant protein attained compact conformation as compared to the native. The major impact of mutation was observed in the Switch I region which might be the crucial reason behind the loss of interaction between the guanine ring and F28 residue.
Journal Article
Antithymocyte globulin for graft-versus-host disease prophylaxis: an updated systematic review and meta-analysis
by
Reljic, Tea
,
Hamadani, Mehdi
,
Kumar, Ambuj
in
Antilymphocyte serum
,
Blood cancer
,
Bone marrow
2019
Graft-versus-host disease (GVHD) remains a limiting factor for successful allogeneic hematopoietic cell transplantation (allo-HCT). Conflicting data exist on the benefit of ATG on post-transplant survival. We performed a systematic review of randomized controlled trials (RCTs) to assess benefits and harms of thymoglobulin and Fresenius (re-branded as Grafalon) ATG formulations in patients undergoing allo-HCT for a variety of hematologic malignancies and bone marrow failure syndromes. A comprehensive search of MEDLINE, EMBASE, and Cochrane Library was performed. Data on methodological quality, benefits, and harms were extracted for each trial and pooled under a random-effects model. Eight RCTs (1134 patients) met the inclusion criteria. Methodological quality ranged from moderate to very low. Pooled results showed no difference in overall survival (OS) with the use of ATG (hazard ratio (HR) = 0.97; 95% confidence interval (CI) = 0.74–1.28; P = 0.83). ATG reduced grade II/III acute GVHD (risk ratio (RR) = 0.61; 95% CI = 0.48–0.77; P < 0.0001), grade III/IV acute GVHD (RR = 0.52; 95% CI = 0.34–0.81; P = 0.004), and chronic GVHD (RR = 0.52; 95% CI = 0.40–0.69; P < 0.00001) without an increase in non-relapse mortality (NRM) (RR = 0.91; 95% CI = 0.74–1.13; P = 0.40). Future studies with better methodological quality are needed to provide conclusive answers related to optimal dosing and timing of ATG for prevention of GVHD.
Journal Article
PPAR agonists as add-on treatment with metformin in management of type 2 diabetes: a systematic review and meta-analysis
2024
The combination of metformin and the peroxisome proliferator-activated receptors (PPAR) agonists offers a promising avenue for managing type 2 diabetes (T2D) through their potential complementary mechanisms of action. The results from randomized controlled trials (RCT) assessing the efficacy of PPAR agonists plus metformin versus metformin alone in T2D are inconsistent, which prompted the conduct of the systematic review and meta-analysis. We searched MEDLINE and EMBASE from inception (1966) to March 2023 to identify all RCTs comparing any PPAR agonists plus metformin versus metformin alone in T2D. Categorical variables were summarized as relative risk along with 95% confidence interval (CI). Twenty RCTs enrolling a total of 6058 patients met the inclusion criteria. The certainty of evidence ranged from moderate to very low. Pooled results show that using PPAR agonist plus metformin, as compared to metformin alone, results in lower concentrations of fasting glucose [MD = − 22.07 mg/dl (95% CI − 27.17, − 16.97), HbA1c [MD = − 0.53% (95% CI − 0.67, − 0.38)], HOMA-IR [MD = − 1.26 (95% CI − 2.16, − 0.37)], and fasting insulin [MD = − 19.83 pmol/L (95% CI − 29.54, − 10.13)] without significant increase in any adverse events. Thus, synthesized evidence from RCTs demonstrates the beneficial effects of PPAR agonist add-on treatment versus metformin alone in T2D patients. In particular, novel dual PPARα/γ agonist (tesaglitazar) demonstrate efficacy in improving glycaemic and lipid concentrations, so further RCTs should be performed to elucidate the long-term outcomes and safety profile of these novel combined and personalized therapeutic strategies in the management of T2D.
PROSPERO registration no. CRD42023412603.
Journal Article