Integration of ligand and structure-based pharmacophore screening for the identification of novel natural leads against Euchromatic histone lysine methyltransferase 2 (EHMT2/G9a).

Herein, we report a blended ligand and structure-based pharmacophore screening approach to identify new natural leads against the Protein Lysine Methyltransferase 2 (EHMT2/G9a). The EHMT2/G9a has been associated with Cancer, Alzheimer's, and aging and is considered an emerging drug target having no clinically passed inhibitor. Purposefully, we developed the ligand-based pharmacophore (Pharmacophore-L) based on the common features of known inhibitors and the structure-based pharmacophore (Pharmacophore-S) based on the interaction profile of available crystal structures. The Pharmacophore-L and Pharmacophore-S were subjected to multiple tiers of validations and utilized in combination for the screening of total 741543 compounds coming from multiple databases. Additional layers of stringency were applied in the screening process to test drug-likeness (using Lipinski's rule, Veber's rule, SMARTS and ADMET filtration), to rule out any toxicity (TOPKAT analysis). The interaction profiles, stabilities, and comparative analysis against the reference were carried out by flexible docking, MD simulation, and MM-GBSA analysis, which finally led to three leads as potential inhibitors of G9a.Communicated by Ramaswamy H. Sarma.

Viral inhibitory potential of hyoscyamine in Japanese encephalitis virus-infected embryonated chicken eggs involving multiple signaling pathways.

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis worldwide. The emergence of new genotypes of the virus and a high rate of mutation make it necessary to develop alternative treatment strategies against this deadly pathogen. Although the antiviral properties of Atropa belladonna and some of its active components, such as atropine and scopolamine, have been studied, the effect of another important component, hyoscyamine, against JEV infection has not yet been investigated. In this study, we investigated the antiviral effect of hyoscyamine against JEV and its immunomodulatory activity in embryonated chicken eggs. Pretreatment with hyoscyamine sulphate resulted in a significant decrease in the viral load in both chorioallantoic membrane (CAM) and brain tissues at 48 and 96 hours postinfection. In silico studies showed stable binding and interaction between hyoscyamine and non-structural protein 5 (NS5), suggesting that this could be the basis of its antiviral effect. Embryonated eggs pretreated with hyoscyamine sulphate showed upregulation of Toll-like receptor 3 (TLR3), TLR7, TLR8, interleukin 4 (IL-4), and IL-10 as well as interferons and regulatory factors. Hyoscyamine sulphate was also found to cause significant downregulation of TLR4. The potential use of hyoscyamine for controlling JEV replication and its dissemination to the brain suggest that it may be a promising therapy option against JEV in the future.

Structural analysis of human ATE1 isoforms and their interactions with Arg-tRNAArg.

Posttranslational protein arginylation has been shown as a key regulator of cellular processes in eukaryotes by affecting protein stability, function, and interaction with macromolecules. Thus, the enzyme Arginyltransferase and its targets, are of immense interest to modulate cellular processes in the normal and diseased state. While the study on the effect of this posttranslational modification in mammalian systems gained momentum in the recent times, the detail structures of human ATE1 (hATE1) enzymes has not been investigated so far. Thus, the purpose of this study was to predict the overall structure and the structure function relationship of hATE1 enzyme and its four isoforms. The structure of four ATE1 isoforms were modelled and were docked with 3'end of the Arg-tRNAArg which acts as arginine donor in the arginylation reaction, followed by MD simulation. All the isoforms showed two distinct domains. A compact domain and a somewhat flexible domain as observed in the RMSF plot. A distinct similarity in the overall structure and interacting residues were observed between hATE1-1 and X4 compared to hATE1-2 and 5. While the putative active sites of all the hATE1 isoforms were located at the same pocket, differences were observed in the active site residues across hATE1 isoforms suggesting different substrate specificity. Mining of nsSNPs showed several nsSNPs including cancer associated SNPs with deleterious consequences on hATE1 structure and function. Thus, the current study for the first time shows the structural differences in the mammalian ATE1 isoforms and their possible implications in the function of these proteins.Communicated by Ramaswamy H. Sarma.

Evaluation of the Viability of Auditory Steady State Response Testing for Detection of Pseudohypacusis in Serving Personnel of the Indian Armed Forces.

The most popular objective physiologic test for detecting hearing loss that is in use today is the ABR, however it is not frequency specific. The frequency specific tool available for evaluation of hearing is ASSR. The study is aimed to assess the ability of ASSR to estimate hearing thresholds and identify the ideal modulation frequency in hearing impaired personnel. All subjects and controls were subjected to PTA to determine presence/absence of hearing loss, and the nature and configuration of the hearing loss if any. The subjects were then subjected to ASSR testing to objectively ascertain hearing thresholds. The PTA thresholds obtained and the hearing thresholds obtained by ASSR were correlated in this study. The study was carried out in 100 subjects under the age of 50 years (50 with normal hearing & 50 with impaired hearing by PTA) after obtaining informed consent. Moderate correlation was found between PTA and ASSR thresholds only in certain frequencies while in other frequencies the correlation though present, was low. This study concluded that ASSR system could be used to estimate hearing thresholds only approximately as no significant linear correlations were found between PTA thresholds and ASSR at the tested frequencies.

3D QSAR pharmacophore based lead identification of G9a lysine methyltransferase towards epigenetic therapeutics.

The G9a, Lysine Methyltransferase that methylates the histone 3 lysine 9 (H3K9) of the nucleosome, is an excellent epigenetic target having no clinically passed inhibitor currently owing to adverse in vivo ADMET toxicities. In this work, we have carried out detailed computational investigations to find novel and safer lead against the target using advanced 3 D QSAR pharmacophore screening of databases containing more than 400000 entrees of natural compounds. The screening was conducted at different levels at increasing stringencies by employing pharmacophore mapping, druglikenesses and interaction profiles of the selected to identify potential hit compounds. The potential hits were further screened by advanced flexible docking, ADME and toxicity analysis to eight hit compounds. Based on the comparative analysis of the hits with the reference inhibitor, we identified one lead inhibitor against the G9a, having better binding efficacy and a safer ADMET profile than the reference inhibitor. Finally, the results were further verified using robust molecular dynamics simulation and MM-GBSA binding energy calculation. The natural compounds are generally considered benign due to their long human uses and this is the first attempt of in silico screening of a large natural compound library against G9a to our best knowledge. Therefore, the finding of this study may add value towards the development of epigenetic therapeutics against the G9a.Communicated by Ramaswamy H. Sarma.

Role of Mastoidectomy with Type 1 Tympanoplasty in Paediatric Patients with Poor Contralateral Ear Status.

The aim of the study was to assess the role of mastoidectomy with type 1 tympanoplasty in the management of paediatric patients with poor contralateral ear status and to evaluate the prognostic factors that may influence the success outcome of type 1 tympanoplasty. A prospective study of 112 paediatric patients from 4 to 12 years of age. All patients in the study had bilateral ear perforations. They were randomly assigned to undergo either type 1 tympanoplasty (group 1, n = 56) or type 1 tympanoplasty with mastoidectomy (group 2, n = 56). The outcomes between the two groups were compared at 12 months postoperative period. The outcomes evaluated were: 1. anatomical condition of the tympanic membrane, 2. functional improvement in hearing (≥ 10 db), 3. air-filled middle ear space without atelectasis or otitis media with effusion, 4. overall outcome. The outcomes were also compared in both the surgical groups for patients who were ≤ 8 years (n = 51) and > 8 years (n = 61) of age. Prognostic factors for success outcome for type 1 tympanoplasty were evaluated. The prognostic factors considered were age at the time of surgery, age groups, duration of the disease prior to surgery, previous adenoidectomy, mechanism of perforation, location of perforation, size of the perforation, type of ear surgery performed (tympanoplasty with or without mastoidectomy). The success outcome in anatomical condition of the tympanic membrane was significantly higher in mastoidectomy group (p = 0.015) but was not significantly different in those ≤ 8 years and > 8 years (p = 0.112, p = 0.064 respectively).There was no difference in the functional improvement in hearing in both the surgical groups for all patients, ≤ 8 years and > 8 years (p = 0.188 p = 0.061, p = 0.865 respectively). Mastoidectomy group showed significantly higher success outcome for air-filled middle ear space without atelectasis or OME for all patients, ≤ 8 years and > 8 years (p < 0.001, p = 0.004, p = 0.041 respectively).Overall success was significantly higher in mastoidectomy group for all patients and ≤ 8 years (p = 0.040, p = 0.012 respectively),but not significantly different for > 8 years (p = 0.592).Out of the prognostic factors considered for success only the type of ear surgery performed showed as a better predictor for success (AUC = 0.606, p = 0.046). Cortical mastoidectomy done along with type 1 tympanoplasty in paediatric patients with poor contralateral ear showed statistically significant higher overall success outcome. Although mastoidectomy done with type 1 tympanoplasty showed better success outcome in patients above 8 years, it was not statistically significant. Except the type of ear surgery performed, none of the prognostic factors considered could influence the success outcome. Our study recommends mastoidectomy to be combined with type 1 tympanoplasty in paediatric patients aged ≤ 8 years with poor contralateral ear status to enhance the overall success outcome.

Other Rare Sinonasal Malignant Tumours Involving the Anterior Skull Base.

Sinonasal tumours are rare, and among these there exist a small number of histologic subtypes that are infrequently encountered and rarely mentioned in the literature. These have been presented as either case reports or small case series, and their very low incidence makes prospective studies practically impossible. This review analyses the available literature, including our own experience and endeavours to outline management strategies, which involve a high index of suspicion and counselling of patients. In most instances, these tumours require aggressive multimodal treatment to improve survival outcomes. The overall prognosis remains dismal.