A conserved polar residue plays a critical role in mismatch detection in A-family DNA polymerases.

In A-family DNA polymerases (dPols), a functional 3'-5' exonuclease activity is known to proofread newly synthesized DNA. The identification of a mismatch in substrate DNA leads to transfer of the primer strand from the polymerase active site to the exonuclease active site. To shed more light regarding the mechanism responsible for the detection of mismatches, we have utilized DNA polymerase 1 from Aquifex pyrophilus (ApPol1). The enzyme synthesized DNA with high fidelity and exhibited maximal exonuclease activity with DNA substrates bearing mismatches at the -2 and - 3 positions. The crystal structure of apo-ApPol1 was utilized to generate a computational model of the functional ternary complex of this enzyme. The analysis of the model showed that N332 forms interactions with minor groove atoms of the base pairs at the -2 and - 3 positions. The majority of known A-family dPols show the presence of Asn at a position equivalent to N332. The N332L mutation led to a decrease in the exonuclease activity for representative purine-pyrimidine, and pyrimidine-pyrimidine mismatches at -2 and - 3 positions, respectively. Overall, our findings suggest that conserved polar residues located towards the minor groove may facilitate the detection of position-specific mismatches to enhance the fidelity of DNA synthesis.

An acetyltransferase effector conserved across Legionella species targets the eukaryotic eIF3 complex to modulate protein translation.

The survival of Legionella spp. as intracellular pathogens relies on the combined action of protein effectors delivered inside their eukaryotic hosts by the Dot/Icm (defective in organelle trafficking/intracellular multiplication) type IVb secretion system. The specific repertoire of effector arsenals varies dramatically across over 60 known species of this genera with Legionella pneumophila responsible for most cases of Legionnaires' disease in humans encoding over 360 Dot/Icm effectors. However, a small subset of "core" effectors appears to be conserved across all Legionella species raising an intriguing question of their role in these bacteria's pathogenic strategy, which for most of these effectors remains unknown. L. pneumophila Lpg0103 effector, also known as VipF, represents one of the core effector families that features a tandem of Gcn5-related N-acetyltransferase (GNAT) domains. Here, we present the crystal structure of the Lha0223, the VipF representative from Legionella hackeliae in complex with acetyl-coenzyme A determined to 1.75 Å resolution. Our structural analysis suggested that this effector family shares a common fold with the two GNAT domains forming a deep groove occupied by residues conserved across VipF homologs. Further analysis suggested that only the C-terminal GNAT domain of VipF effectors retains the active site composition compatible with catalysis, whereas the N-terminal GNAT domain binds the ligand in a non-catalytical mode. We confirmed this by in vitro enzymatic assays which revealed VipF activity not only against generic small molecule substrates, such as chloramphenicol, but also against poly-L-lysine and histone-derived peptides. We identified the human eukaryotic translation initiation factor 3 (eIF3) complex co-precipitating with Lpg0103 and demonstrated the direct interaction between the several representatives of the VipF family, including Lpg0103 and Lha0223 with the K subunit of eIF3. According to our data, these interactions involve primarily the C-terminal tail of eIF3-K containing two lysine residues that are acetylated by VipF. VipF catalytic activity results in the suppression of eukaryotic protein translation in vitro, revealing the potential function of VipF "core" effectors in Legionella's pathogenic strategy.IMPORTANCEBy translocating effectors inside the eukaryotic host cell, bacteria can modulate host cellular processes in their favor. Legionella species, which includes the pneumonia-causing Legionella pneumophila, encode a widely diverse set of effectors with only a small subset that is conserved across this genus. Here, we demonstrate that one of these conserved effector families, represented by L. pneumophila VipF (Lpg0103), is a tandem Gcn5-related N-acetyltransferase interacting with the K subunit of human eukaryotic initiation factor 3 complex. VipF catalyzes the acetylation of lysine residues on the C-terminal tail of the K subunit, resulting in the suppression of eukaryotic translation initiation factor 3-mediated protein translation in vitro. These new data provide the first insight into the molecular function of this pathogenic factor family common across Legionellae.

Structural characterization of the Sel1-like repeat protein LceB from Legionella pneumophila.

Legionella are freshwater Gram-negative bacteria that in their normal environment infect protozoa. However, this adaptation also allows Legionella to infect human alveolar macrophages and cause pneumonia. Central to Legionella pathogenesis are more than 330 secreted effectors, of which there are nine core effectors that are conserved in all pathogenic species. Despite their importance, the biochemical function of several core effectors remains unclear. To address this, we have taken a structural approach to characterize the core effector of unknown function LceB, or Lpg1356, from Legionella pneumophila. Here, we solve an X-ray crystal structure of LceB using an AlphaFold model for molecular replacement. The experimental structure shows that LceB adopts a Sel1-like repeat (SLR) fold as predicted. However, the crystal structure captured multiple conformations of LceB, all of which differed from the AlphaFold model. A comparison of the predicted model and the experimental models suggests that LceB is highly flexible in solution. Additionally, the molecular analysis of LceB using its close structural homologs reveals sequence and structural motifs of known biochemical function. Specifically, LceB harbors a repeated KAAEQG motif that both stabilizes the SLR fold and is known to participate in protein-protein interactions with eukaryotic host proteins. We also observe that LceB forms several higher-order oligomers in solution. Overall, our results have revealed that LceB has conformational flexibility, self-associates, and contains a molecular surface for binding a target host-cell protein. Additionally, our data provides structural insights into the SLR family of proteins that remain poorly studied.

Assessment of Bone Loss Around Dental Implant in Smokers.

Objectives: This research was done to assess how much bone is lost around dental implants in smokers. Material and Method: There were 80 participants total in the study, 40 of whom were smokers (Group I) and 40 of who were non-smokers (Group II). By evaluating the patients' clinical and radiographic data, the marginal bone-level measurements were determined. The acquired information underwent statistical analysis. Results: Smokers were found to have worse overall clinical parameters than non-smokers (P 0.05). Smokers experience more marginal bone loss around implants than non-smokers do. Conclusion: Smoking has a negative impact on the outcome rate of dental implants.

Smartphone for retinal imaging - Case series in resource-limited rural settings.

Purpose: There is a clinical need for a cost-effective, reliable, easy-to-use, and portable retinal photography. The use of smartphone fundus photography for documentation of retinal changes in resource-limited settings, where retinal imaging was not previously possible, is studied here. The introduction of smartphone-based retinal imaging has resulted in the increase in available technologies for fundus photography. On account of the cost, fundus cameras are not readily available in ophthalmic practice in developing countries. Because smartphones are readily available, easy to use, and also portable, they present a low-cost alternative method in resource-limited settings. The aim is to explore the use of smartphones (iphones) for retinal imaging in resource-limited settings. Methods: A smartphone (iphone) was used to acquire retinal images with the use of +20 D lens in patients with dilated pupils by activating the video mode of the camera. Results: Clear retinal images were obtained in different clinical conditions in adults and children, including branch retinal vein occlusion with fibro-vascular proliferation, choroidal neo-vascular membranes, presumed ocular toxoplasmosis, diabetic retinopathy, retinoblastoma, ocular albinism, and hypertensive retinopathy. Conclusion: New inexpensive, portable, easy-to-operate cameras have revolutionized retinal imaging and screening programs and play an innovative role in research, education, and information sharing.

Integrating Depression and Alcohol Use Care Into Primary Care in Low- and Middle-Income Countries: A Meta-Analysis.

OBJECTIVE: Evaluation of the effectiveness of integration of depression and alcohol use disorder care into primary health care in low- and middle-income countries (LMICs) is limited. The authors aimed to quantify the effectiveness of integrating mental health care into primary care by examining depression and alcohol use disorder outcomes. The study updates a previous systematic review summarizing research on care integration in LMICs. METHODS: Following PRISMA guidelines, the authors included studies from the previous review and studies published from 2017 to 2020 that included adults with alcohol use disorder or depression. Studies were evaluated for type of integration model with the typology developed previously. A meta-analysis using a random-effects model to assess effectiveness of integrated interventions was conducted. Meta-regression analyses to examine the impact of study characteristics on depression and alcohol use disorder outcomes were conducted. RESULTS: In total, 49 new articles were identified, and 74 articles from the previous and current studies met inclusion criteria for the meta-analysis. Overall random effect sizes were 0.28 (95% CI=0.22-0.35) and 0.17 (95% CI=0.11-0.24) for studies targeting care integration for depression or for alcohol use disorder, respectively, into primary care in LMICs. High heterogeneity within and among studies was observed. No significant association was found between country income level and depression and alcohol use outcomes. However, differences in effect sizes between types of integration model were statistically significant (p<0.001). CONCLUSIONS: Integration of mental health care into primary health care in LMICs was found to improve depression and alcohol use disorder outcomes. This evidence should be considered when designing interventions to improve mental health screening and treatment in LMICs.

The atypical thioredoxin 'Alr2205', a newly identified partner of the typical 2-Cys-Peroxiredoxin, safeguards the cyanobacterium Anabaena from oxidative stress.

Thioredoxins (Trxs) are ubiquitous proteins that play vital roles in several physiological processes. Alr2205, a thioredoxin-like protein from Anabaena PCC 7120, was found to be evolutionarily closer to the Trx-domain of the NADPH-Thioredoxin Reductase C than the other thioredoxins. The Alr2205 protein showed disulfide reductase activity despite the presence a non-canonical active site motif 'CPSC'. Alr2205 not only physically interacted with, but also acted as a physiological reductant of Alr4641 (the typical 2-Cys-Peroxiredoxin from Anabaena), supporting its peroxidase function. Structurally, Alr2205 was a monomeric protein that formed an intramolecular disulfide bond between the two active site cysteines (Cys-38 and Cys-41). However, the Alr2205C41S protein, wherein the resolving cysteine was mutated to serine, was capable of forming intermolecular disulfide bond and exist as a dimer when treated with H2O2. Overproduction of Alr2205 in E. coli protected cells from heavy metals, but not oxidative stress. To delve into its physiological role, Alr2205/Alr2205C41S was overexpressed in Anabaena, and the ability of the corresponding strains (An2205+ or An2205C41S+) to withstand environmental stresses was assessed. An2205+ showed higher resistance to H2O2 than An2205C41S+, indicating that the disulfide reductase function of this protein was critical to protect cells from this peroxide. Although, An2205+ did not show increased capability to withstand cadmium stress, An2205C41S+ was more susceptible to this heavy metal. This is the first study that provides a vital understanding into the function of atypical thioredoxins in countering the toxic effects of heavy metals/H2O2 in prokaryotes.

Single-blind, randomized study comparing clinical equivalence of trulene and prolene polypropylene sutures in elective primary coronary artery bypass graft surgery.

BACKGROUND: Coronary artery bypass graft surgery (CABG) is one of the principle therapies for coronary artery disease, as it improves survival rate and quality of life (QoL). Polypropylene suture is commonly used in vascular and cardiac surgeries for anastomosis due to its long-term tensile strength and minimal tissue trauma. This study compared the clinical equivalence of Trulene® (Healthium Medtech Limited) and Prolene® (Ethicon-Johnson & Johnson) polypropylene sutures regarding incidence of myocardial infarction, stroke, renal failure and cardiac death (MACCE) occurring up to 26 weeks' period post-CABG surgery. METHODS: This multicenter, prospective, two-arm, parallel-group, randomized (1:1), single-blind study (n = 89) was conducted between August 2020 and September 2021. The primary endpoint, post-surgery cumulative incidence of MACCE was evaluated. In addition, anastomotic revision, surgical site infection (SSI), operative time, length of post-operative hospital stay, repeat revascularization, intraoperative suture handling characteristics, time taken to return to work and resume normal day to day activities, subject satisfaction score and QoL, and other adverse events were also recorded. RESULTS: A total of 80 (89.89%) males and 9 (10.11%) females participated in the study. No incidence of MACCE was recorded in any of the study participants. Non-significant difference was observed in anastomotic revision, SSI, operative time, post-operative hospital stay, revascularization, return to work and normal day-to-day activities, subject satisfaction score and QoL, and intraoperative handling parameters (except ease of passage) between the treatment groups, Trulene® and Prolene®. Compared to screening visit, proportion of subjects with 'no problems' for each QoL dimension and the mean visual analogue scale increased with each subsequent follow-up visit. CONCLUSION: Trulene® polypropylene suture is clinically equivalent to Prolene® polypropylene suture and is safe and effective for anastomosis construction in CABG surgery during a routine clinical procedure. Trial registration CTRI Registration No.: CTRI/2020/05/025157 (Registered on: 13/05/2020).

A broadly neutralizing monoclonal antibody overcomes the mutational landscape of emerging SARS-CoV-2 variants of concern.

The emergence of new variants of SARS-CoV-2 necessitates unremitting efforts to discover novel therapeutic monoclonal antibodies (mAbs). Here, we report an extremely potent mAb named P4A2 that can neutralize all the circulating variants of concern (VOCs) with high efficiency, including the highly transmissible Omicron. The crystal structure of the P4A2 Fab:RBD complex revealed that the residues of the RBD that interact with P4A2 are a part of the ACE2-receptor-binding motif and are not mutated in any of the VOCs. The pan coronavirus pseudotyped neutralization assay confirmed that the P4A2 mAb is specific for SARS-CoV-2 and its VOCs. Passive administration of P4A2 to K18-hACE2 transgenic mice conferred protection, both prophylactically and therapeutically, against challenge with VOCs. Overall, our data shows that, the P4A2 mAb has immense therapeutic potential to neutralize the current circulating VOCs. Due to the overlap between the P4A2 epitope and ACE2 binding site on spike-RBD, P4A2 may also be highly effective against a number of future variants.

Antibody multispecificity: A necessary evil?

Antibodies represent key effectors of the adaptive immune system. The specificity of antibodies is an established hallmark of the immune response. However, a certain proportion of antibodies exhibit limited promiscuity or multireactivity. Germline antibodies display plasticity which imparts multispecificity to enhance the antibody repertoire. Surprisingly, even affinity matured antibodies display such plasticity and multireactivity enabling their binding to more than one antigen. We propose that antibody multispecificity is a physiological requirement to expand the antibody repertoire at the germline level and to tolerate plasticity in antigens at the mature level. This property of the humoral immune response may attenuate the ability of infectious RNA viruses such as influenza, HIV and SARS-CoV-2 to acquire mutations that render resistance to neutralizing antibodies.

Genome-wide characterization and identification of cyclophilin genes associated with leaf rust resistance in bread wheat (Triticum aestivum L.).

Cyclophilins (CYPs) are a group of highly conserved proteins involved in host-pathogen interactions in diverse plant species. However, the role of CYPs during disease resistance in wheat remains largely elusive. In the present study, the systematic genome-wide survey revealed a set of 81 TaCYP genes from three subfamilies (GI, GII, and GIII) distributed on all 21 wheat chromosomes. The gene structures of TaCYP members were found to be highly variable, with 1-14 exons/introns and 15 conserved motifs. A network of miRNA targets with TaCYPs demonstrated that TaCYPs were targeted by multiple miRNAs and vice versa. Expression profiling was done in leaf rust susceptible Chinese spring (CS) and the CS-Ae. Umbellulata derived resistant IL "Transfer (TR). Three homoeologous TaCYP genes (TaCYP24, TaCYP31, and TaCYP36) showed high expression and three homoeologous TaCYP genes (TaCYP44, TaCYP49, and TaCYP54) showed low expression in TR relative to Chinese Spring. Most of the other TaCYPs showed comparable expression changes (down- or upregulation) in both contrasting TR and CS. Expression of 16 TaCYPs showed significant association (p < 0.05) with superoxide radical and hydrogen peroxide abundance, suggesting the role of TaCYPs in downstream signaling processes during wheat-leaf rust interaction. The differentially expressing TaCYPs may be potential targets for future validation using transgenic (overexpression, RNAi or CRISPR-CAS) approaches and for the development of leaf rust-resistant wheat genotypes.

Determination of Effectiveness of Photobiomodulation in the Treatment of Oral Submucous Fibrosis.

Context: Oral submucous fibrosis (OSMF) is chronic, scarring disease of the oral cavity. Cytokines and growth factors produced by inflammatory cells play a major role in its pathogenesis. Low-level laser therapy (LLLT) application, which has an anti-inflammatory, was used to determine the improvement in mouth opening. Aims: The aim of the study is to evaluate the effectiveness of laser photobiomodulation (PBM) in OSMF treatment. Materials and Methods: Thirty patients who were diagnosed with OSMF after obtaining consent form and ethical clearance were included. LLLT was applied for 4 cycles for 15 s each in the left and right buccal mucosa. Therapy was done on day 0, 3, 7, and 15 and measurements were done immediately after each LLLT application. Patients were recalled after 1, 3, and 6 months from the commencement of the therapy for follow-up measurements. Results: The mean increase in mouth opening following application of LLLT from day 0 to day 15 was 9.91 ± 3.34, and day 1-6 months was 14.29 ± 6.82, which was statistically significant. Conclusions: The study shows significant improvements in the mouth opening of the OSMF patient during treatment and postoperatively. Thus, our study confirms LLLT can be used as one of the modality in OSMF management.

Genome-Wide Identification and Expression Analysis of the Thioredoxin (Trx) Gene Family Reveals Its Role in Leaf Rust Resistance in Wheat (Triticum aestivum L.).

Bread wheat (Triticum aestivum L.; Ta) is the staple cereal crop for the majority of the world's population. Leaf rust disease caused by the obligate fungal pathogen, Puccinia triticina L., is a biotrophic pathogen causing significant economic yield damage. The alteration in the redox homeostasis of the cell caused by various kinds of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in response to pathogenic infections is controlled by redox regulators. Thioredoxin (Trx) is one of the redox regulators with low molecular weight and is thermostable. Through a genome-wide approach, forty-two (42) wheat Trx genes (TaTrx) were identified across the wheat chromosome groups A, B, and D genomes containing 12, 16, and 14 Trx genes, respectively. Based on in silico expression analysis, 15 TaTrx genes were selected and utilized for further experimentation. These 15 genes were clustered into six groups by phylogenetic analysis. MicroRNA (miRNA) target analysis revealed eight different miRNA-targeted TaTrx genes. Protein-protein interaction (PPI) analysis showed TaTrx proteins interact with thioredoxin reductase, peroxiredoxin, and uncharacterized proteins. Expression profiles resulting from quantitative real-time PCR (qRT-PCR) revealed four TaTrx genes (TaTrx11-5A, TaTrx13-5B, TaTrx14-5D, and TaTrx15-3B) were significantly induced in response to leaf rust infection. Localization of ROS and its content estimation and an assay of antioxidant enzymes and expression analysis suggested that Trx have been involved in ROS homeostasis at span 24HAI-72HAI during the leaf rust resistance.

Pfprex from Plasmodium falciparum can bypass oxidative stress-induced DNA lesions.

Apicomplexans such as the malaria parasite Plasmodium falciparum possess a unique organelle known as the apicoplast that has its own circular genome. The apicoplast genome is AT rich and is subjected to oxidative stress from the byproducts of the normal biochemical pathways that operate in the apicoplast. It is expected that oxidative stress will lead to the appearance of DNA lesions such as 2-hydroxydeoxyadenine, thymine glycol, and 8-oxodeoxyguanine in the apicoplast genome. The apicoplast genome is replicated by the DNA polymerase activity present in the Pfprex enzyme. We have named the polymerase module of Pfprex as PfpPol and the enzyme belongs to the A family of DNA polymerases. Similar to other members of this family, PfpPol also exhibits high fidelity of DNA synthesis. We show that this enzyme is also capable of carrying out translesion DNA synthesis past common DNA lesions that arise due to oxidative stress. The residues N505 and Y509 from the fingers sub-domain, which are unique to PfpPol, play an important role in the ability of PfpPol to bypass the three lesions. The observed lesion-bypass ability of the Pfprex enzyme will minimize the adverse effects of oxidative stress on the apicoplast genome of the malaria parasite. These findings also have implications regarding the evolution of the machinery responsible for replication of organellar genomes.

Analysis of NIA and GSNOR family genes and nitric oxide homeostasis in response to wheat-leaf rust interaction.

Nitric oxide (NO) modulates plant response to biotic and abiotic stresses by S-nitrosylation-mediated protein post-translational modification. Nitrate reductase (NR) and S-nitrosoglutathione reductase (GSNOR) enzymes are essential for NO synthesis and the maintenance of Nitric oxide/S-nitroso glutathione (NO/GSNO) homeostasis, respectively. S-nitrosoglutathione, formed by the S-nitrosylation reaction of NO with glutathione, plays a significant physiological role as the mobile reservoir of NO. The genome-wide analysis identified nine NR (NIA) and three GSNOR genes in the wheat genome. Phylogenic analysis revealed that the nine NIA genes +were clustered into four groups and the 3 GSNORs into two groups. qRT-PCR expression profiling of NIAs and GSNORs was done in Chinese spring (CS), a leaf rust susceptible wheat line showing compatible interaction, and Transfer (TR), leaf rust-resistant wheat line showing incompatible interaction, post-inoculation with leaf rust pathotype 77-5 (121-R-63). All the NIA genes showed upregulation during incompatible interaction in comparison with the compatible reaction. The GSNOR genes showed a variable pattern of expression: the TaGSNOR1 showed little change, whereas TaGSNOR2 showed higher expression during the incompatible response. TaGSNOR3 showed a rise of expression both in compatible and incompatible reactions. Before inoculation and after 72 h of pathogen inoculation, NO localization was studied in both compatible and incompatible reactions. The S-nitrosothiol accumulation, NR, and glutathione reductase activity showed a consistent increase in the incompatible interactions. The results demonstrate that both NR and GSNOR plays significant role in defence against the leaf rust pathogen in wheat by modulating NO homeostasis or signalling.

Comparative evaluation of fluconazole and clotrimazole in treatment of oral candidiasis.

Context: Oral candidiasis is the most common opportunistic infection affecting the oral mucosa. Most commonly, the lesions are caused by Candida albicans and other organisms isolated are Candida glabrata, Candida krusei, Candida parapsilosis and Candida dubliniensis. As an opportunistic infection, it is seen affecting the young, old and debilitating people. This infection is seen to be enervative, exhausting and crippling; a few routinely employed antifungal agents are used in our study. Aims: We aimed to compare the clinical and mycological effectiveness of topical fluconazole and clotrimazole in the treatment of oral candidiasis. Settings and Design: A total of 40 subjects were taken and randomly divided into two groups of 20 each. Group 1 included patients treated with topical clotrimazole and Group 2 included patients treated with topical fluconazole. Subjects and Methods: Patients were graded according to severity, and swab was taken for species identification and colony count. Patients were treated with clotrimazole and fluconazole according to their group they were also assessed post treatment for clinical signs and colony count changes. Statistical Analysis Used: Data were analyzed using the statistical package SPSS 22.0 (SPSS Inc., Chicago, IL, USA), and the level of significance was set at P < 0.05. Descriptive statistics was performed to assess the mean and standard deviation of the respective groups. Results: The clinical resolution rate of 80% and 100% was noted in the clotrimazole and fluconazole groups, respectively. The mycological cure rate of 82.52% and 86.38% was noted in the clotrimazole and fluconazole groups, respectively. Statistically significant results were obtained in clinical resolution rates and no significant results were obtained when mycological cure rates were compared. Conclusions: We conclude that the clinical cure rate of fluconazole is slightly better than clotrimazole while mycological cure rate was approximately similar.

Efficacy of Curcumin and Topical Steroids in the Treatment for Oral Submucous Fibrosis: A Comparative study.

CONTEXT: Oral submucous fibrosis (OSMF) is a chronic debilitating disease of the oral cavity, characterized by inflammation and progressive fibrosis of the submucosal tissues. The main agent involved in the pathogenesis of OSMF is areca nut. A wide range of treatment, including drug management, surgical therapy, and physiotherapy, has been attempted till date, with varying degrees of benefit. AIMS: The objective of this study was to assess efficacy of curcumin for the treatment of OSMF; to asses efficacy of topical steroids for the treatment of OSMF; and to compare the efficacy of curcumin and topical steroid for the treatment of OSMF. SETTING AND DESIGN: Participants were assessed based subjective and objective feature of OSMF, i.e., burning sensation of the oral cavity and interincisal distance, respectively. METHODOLOGY: Thirty participants were categorized into two groups: Group A was administered curcumin and Group B was administered topical steroids for a period of 3 months and followed up after 6 months. The assessment was based on maximal incisal opening and burning sensation for spicy food on Visual Analog Scale score. ANALYSIS: Independent t test was applied for comparison within the group, ANOVA Bonferroni post hoc test was applied for multiple comparison of mean and Mann-Whitney U test was applied to compare the groups. RESULTS: The statistical analysis revealed curcumin to be more efficient than topical steroid. CONCLUSION: The present study demonstrates the efficiency of curcumin and topical steroid to alleviate the clinical findings of OSMF. However, curcumin is comparatively more efficient than steroids for the treatment of OSMF.

Antiviral therapeutics directed against RNA dependent RNA polymerases from positive-sense viruses.

Viruses with positive-sense single stranded RNA (+ssRNA) genomes are responsible for different diseases and represent a global health problem. In addition to developing new vaccines that protect against severe illness on infection, it is imperative to identify new antiviral molecules to treat infected patients. The genome of these RNA viruses generally codes for an enzyme with RNA dependent RNA polymerase (RdRP) activity. This molecule is centrally involved in the duplication of the RNA genome. Inhibition of this enzyme by small molecules will prevent duplication of the RNA genome and thus reduce the viral titer. An overview of the different therapeutic strategies used to inhibit RdRPs from +ssRNA viruses is provided, along with an analysis of these enzymes to highlight new binding sites for inhibitors.

Recurrent tracheal tumor with a critical airway requiring 'Y' stent - unique presentation of tuberculosis.

Tracheal tumor is a rare entity. Tracheal tumor may be a primary tracheal tumor or secondary to invasion from a mediastinal tumor (or a lymph node). These tumors are prone to cause critical airway obstruction which may require urgent care. Tuberculosis is one of the common differential diagnoses of mediastinal lymphadenopathy in TB endemic countries, though isolated tuberculous mediastinal lymphadenopathy without a lung involvement is rare. We report an extremely rare case of isolated paratracheal lymphadenitis due to tuberculosis, eroding the trachea and presented a lower tracheal tumor, which recurred again after complete debulking. Finally, the disease required a 'Y' stent placement, to stabilize the airway following the second recanalization. We discuss the incidence, differential diagnosis, and the bronchoscopic, interventional aspects of this entity.

The PHP domain of PolX from Staphylococcus aureus aids high fidelity DNA synthesis through the removal of misincorporated deoxyribo-, ribo- and oxidized nucleotides.

The X family is one of the eight families of DNA polymerases (dPols) and members of this family are known to participate in the later stages of Base Excision Repair. Many prokaryotic members of this family possess a Polymerase and Histidinol Phosphatase (PHP) domain at their C-termini. The PHP domain has been shown to possess 3'-5' exonuclease activity and may represent the proofreading function in these dPols. PolX from Staphylococcus aureus also possesses the PHP domain at the C-terminus, and we show that this domain has an intrinsic Mn2+ dependent 3'-5' exonuclease capable of removing misincorporated dNMPs from the primer. The misincorporation of oxidized nucleotides such as 8oxodGTP and rNTPs are known to be pro-mutagenic and can lead to genomic instability. Here, we show that the PHP domain aids DNA replication by the removal of misincorporated oxidized nucleotides and rNMPs. Overall, our study shows that the proofreading activity of the PHP domain plays a critical role in maintaining genomic integrity and stability. The exonuclease activity of this enzyme can, therefore, be the target of therapeutic intervention to combat infection by methicillin-resistant-Staphylococcus-aureus.