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Bacteria can adapt to stressful conditions through mutations affecting the RNA polymerase core subunits that lead to beneficial changes in transcription. In response to selection with rifampicin (RIF), mutations arise in the RIF resistance determining region (RRDR) ofrpoBthat reduce antibiotic binding. These changes can also alter transcription and thereby have pleiotropic effects on bacterial fitness. Here, we studied the evolution of resistance inBacillus subtilisto the synergistic combination of RIF and the β-lactam cefuroxime (CEF). Two independent evolution experiments led to the recovery of a singlerpoBallele (S487L) that was able to confer resistance to RIF and CEF through a single mutation. Two other common RRDR mutations made the cells 32x more sensitive to CEF (H482Y) or led to only modest CEF resistance (Q469R). The diverse effects of these three mutations on CEF resistance are correlated with differences in the expression of peptidoglycan (PG) synthesis genes and in the levels of two metabolites crucial in regulating PG synthesis, glucosamine-6-phosphate (GlcN-6-P) and UDP-N-acetylglucosamine (UDP-GlcNAc). We conclude that RRDR mutations can have widely varying effects on pathways important for cell wall biosynthesis, and this may restrict the spectrum of mutations that arise during combination therapy.ImportanceRifampicin (RIF) is one of the most valued drugs in the treatment of tuberculosis. TB treatment relies on a combination therapy, and for multidrug resistant strains may include β-lactams. Mutations inrpoBpresent a common route for emergence of resistance to RIF. In this study, usingB. subtilisas a model, we evaluate the emergence of resistance for the synergistic combination of RIF and the β-lactam cefuroxime (CEF). One clinically-relevantrpoBmutation conferred resistance to both RIF and CEF, whereas two others increased CEF sensitivity. We were able to link these phenotypes to accumulation of specific PG precursors. Mainly, UDP-GlcNAc through its GlmR mediated influence on GlmS activity has a strong impact on CEF resistance. Since these mutations are clinically relevant, these effects on CEF sensitivity may help refine the use of β-lactams in TB therapy.

A prototype persistent current switch is developed for an actively shielded whole-body 1.5 T MRI magnet having an operating current of ∼500 A. The switch is developed using a six-strand CuNi-NbTi conductor. The total length of the conductor used in the PCS is ∼40 m using a bifilar winding technique having a room temperature resistance of 15 Ω and an inductance of 6.6 μH. Two numbers of thermo-foil heaters having a resistance of 90 Ω each are placed between the layers of the winding pack of the switch. The wet-winding technique is followed for the switch using a cryogenic grade epoxy. The characteristics of the switch are performed using a 4 K test rig for its applicability in the 1.5 T MRI magnet. The normal resistance of the switch is measured to be 12.5 Ω at 15 K which is 15% less than the estimated value. The total energy loss onto the switch is estimated to be 0.24% of the ramping energy of the magnet at 6 V charging voltage. The thermal switching profile of the switch is studied and correlated with the total energy loss.

A quench protection system for an actively-shielded whole-body 1.5 T MRI magnet made with wire-in-channel NbTi conductor is presented with two types of coil sub-divisions. The MRI magnet must operate for many years in the hospital, and thereby, it must be completely self-protecting by means of self-activating quench propagation heaters to spread the normal zone in a larger volume of the magnet during a quench i.e. the passive protection system. The total stored energy of the magnet is about 3.7 MJ. The voltage and the temperature of the coils have been simulated with two types of passive quench protection systems using OPERA-Quench program. The maximum inter-layer quench voltage generated in the asymmetric sub-division is 70 V/layer with a peak voltage of 2.6 kV and a hot spot temperature of 248 K. The maximum inter-layer quench voltage generated in the symmetric sub-division is 45 V/layer with a peak voltage of 1.7 kV and a hot spot temperature of 185 K. During a quench, an average driving voltage of 1.3 kV and the associated current of 1.75 A is generated in both quench propagation circuits of the magnet with the symmetric sub-division. The 5 G safety line explodes beyond the permissible limits during a quench of the magnet with the asymmetric sub-division, whereas the 5 G safety region is retained within the permissible limit in case of quench of the magnet with symmetric sub-division.

We present a non-immunogenic, injectable, low molecular weight, amphiphilic hydrogel-based drug delivery system (TB-Gel) that can entrap a cocktail of four front-line antitubercular drugs, isoniazid, rifampicin, pyrazinamide, and ethambutol. We showed that TB-Gel is more effective than oral delivery of the combination of four drugs in reducing the mycobacterial infection in mice. Results show that half the dose of chemotherapeutic drugs is sufficient to achieve a comparable therapeutic effect to that of oral delivery.

Transposon-based strategies provide a powerful and unbiased way to study the bacterial stress response1-8, but these approaches cannot fully capture the complexities of network-based behaviour. Here, we present a network-based genetic screening approach: the transcriptional regulator-induced phenotype (TRIP) screen, which we used to identify previously uncharacterized network adaptations of Mycobacterium tuberculosis to the first-line anti-tuberculosis drug isoniazid (INH). We found regulators that alter INH susceptibility when induced, several of which could not be identified by standard gene disruption approaches. We then focused on a specific regulator, mce3R, which potentiated INH activity when induced. We compared mce3R-regulated genes with baseline INH transcriptional responses and implicated the gene ctpD (Rv1469) as a putative INH effector. Evaluating a ctpD disruption mutant demonstrated a previously unknown role for this gene in INH susceptibility. Integrating TRIP screening with network information can uncover sophisticated molecular response programs.

The immune system interacts with cancer cells in multiple intricate ways that can shield the host against hyper-proliferation but can also contribute to malignancy. Understanding the protective roles of the immune system in its interaction with cancer cells can help device new and alternate therapeutic strategies. Many immunotherapeutic methodologies, including adaptive cancer therapy, cancer peptide vaccines, monoclonal antibodies, and immune checkpoint treatment, have transformed the traditional cancer treatment landscape. However, many questions remain unaddressed. The development of personalized combination therapy and neoantigen-based cancer vaccines would be the avant-garde approach to cancer treatment. Desirable chemotherapy should be durable, safe, and target-specific. Managing both tumor (intrinsic factors) and its microenvironment (extrinsic factors) are critical for successful immunotherapy. This review describes current approaches and their advancement related to monoclonal antibody-related clinical trials, new cytokine therapy, a checkpoint inhibitor, adoptive T cell therapy, cancer vaccine, and oncolytic virus.

Superconducting MRI magnet is the most exhaustive commercial application of superconductivity and helium cryogenics. Cryocooler based Zero-Boil-Off (ZBO) technique is inevitable for the present-day scanner. An MRI cryostat for a 1.5T MRI magnet has been designed with the ZBO technique using a fin-based helium recondenser. A cryocooler based test rig has been developed to characterize the performance of the helium recondenser made of OFHC copper. A two-stage GM cryocooler is used to cool the thermal shield and the helium recondenser. Four liters of liquid helium has been produced using the same heat exchanger. The recondensation test of the heat exchanger is performed up to 6 psi of bath pressure. At 1psi, the recondensation capacity is found to be ~1.5W. This paper briefly discusses the experimental details of the recondensation test along with an analytical calculation.

To enhance robustness of automated Temperature vs parametertype of measurements in a cold exchange gas based sampletemperature control system, a second control loop is being addedto compensate for pressure variations. For this purpose, a methodfor indirect estimation of He gas pressure has been devised andtested. The method depends upon the property that in the closedloop sample temperature control system, the heater power at thesteady state changes with the partial pressure of the cold Heliumgas

Combination chemotherapy can increase treatment efficacy and suppress drug resistance. Knowledge of how to engineer rational, mechanism-based drug combinations, however, remains lacking. Although studies of drug activity have historically focused on the primary drug-target interaction, growing evidence has emphasized the importance of the subsequent consequences of this interaction. Bedaquiline (BDQ) is the first new drug for tuberculosis (TB) approved in more than 40 y, and a species-selective inhibitor of the Mycobacterium tuberculosis (Mtb) ATP synthase. Curiously, BDQ-mediated killing of Mtb lags significantly behind its inhibition of ATP synthase, indicating a mode of action more complex than the isolated reduction of ATP pools. Here, we report that BDQ-mediated inhibition of Mtb's ATP synthase triggers a complex metabolic response indicative of a specific hierarchy of ATP-dependent reactions. We identify glutamine synthetase (GS) as an enzyme whose activity is most responsive to changes in ATP levels. Chemical supplementation with exogenous glutamine failed to affect BDQ's antimycobacterial activity. However, further inhibition of Mtb's GS synergized with and accelerated the onset of BDQ-mediated killing, identifying Mtb's glutamine synthetase as a collateral, rather than directly antimycobacterial, metabolic vulnerability of BDQ. These findings reveal a previously unappreciated physiologic specificity of ATP and a facet of mode-of-action biology we term collateral vulnerability, knowledge of which has the potential to inform the development of rational, mechanism-based drug combinations.

N-acetyl glucosamine-1-phosphate uridyltransferase (GlmU) is a bifunctional enzyme involved in the biosynthesis of Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is a critical precursor for the synthesis of peptidoglycan and other cell wall components. The absence of a homolog in eukaryotes makes GlmU an attractive target for therapeutic intervention. Mycobacterium tuberculosis GlmU (GlmUMt) has features, such as a C-terminal extension, that are not present in GlmUorthologs from other bacteria. Here, we set out to determine the uniqueness of GlmUMt by performing in vivo complementation experiments using RvΔglmU mutant. We found that any deletion of the carboxy-terminal extension region of GlmUMt abolishes its ability to complement the function of GlmUMt. Results show orthologs of GlmU, including its closest ortholog, from Mycobacterium smegmatis, cannot complement the function of GlmUMt. Furthermore, the co-expression of GlmUMt domain deletion mutants with either acetyl or uridyltransferase activities failed to rescue the function. However, co-expression of GlmUMt point mutants with either acetyl or uridyltransferase activities successfully restored the biological function of GlmUMt, likely due to the formation of heterotrimers. Based on the interactome experiments, we speculate that GlmUMt participates in unique interactions essential for its in vivo function.

Cold diodes play a crucial role in various operational aspects of the superconducting magnet of magnetic resonance imaging (MRI) scanners. The forward and reverse characteristics and failure modes are studied for two types of high-power rectifier diode to find their suitability for application at 4.2 K in a whole-body 1.5 T superconducting MRI magnet system. The diodes are characterized at various temperatures (300 K, 77 K and 4.2 K) in the current range up to 600 A. The turn-on voltage of the diodes at 4.2 K is found to be increased by 7–12 times that of room temperature. The diodes show negative differential resistance (NDR) beyond 1 A of forward current at 4.2 K. The forward voltage stabilizes in the range of 1.22–1.24 V after attaining the turn-on voltage in the range of 5–8 V. The significance of NDR is analysed for the MRI magnet. The long-term stability of the forward voltage is studied at 77 K with 550 A of forward current. Two modes of diode failure are also studied to foresee any failure during the operation of the magnet.

Extremophiles are microorganisms that flourish in habitats of extreme environments, including in high concentration of salts, pollutants, high or low temperature, an acidic or alkaline pH. All extreme environments are dominated by microorganisms belonging to Archaea, the third domain of life, evolutionary distinct from Bacteria and Eucarya. Over the past few years, the molecular biology of extremophilic Archaea has stimulated a lot of interest in the field of bioremediation. Bioremediation is the use of microorganisms for the degradation or removal of contaminants. Contamination of soils, sediments and water due to anthropogenic activities is a matter of concern at global level. Bioremediation has emerged as an effective solution for these problems. Most bioremediation research has focused on the processes performed by the domain Bacteria. Recently, extremophiles are the focus of growing interest for bioremediation because they can tolerate very harsh environmental conditions due to their ability to produce an array of molecules or extremozymes capable of functioning in the environment without denaturing. These extremozymes from extremophilic microorganisms have special characteristics such as stability to elevated temperature, extremes of pH, organic solvents and high ion strength. Due to the stability and persistence of these extremophilic microorganisms under adverse environmental conditions, they can be explored finding new species for using in the bioremediation of environments contaminated with extremely recalcitrant pollutants. Here, we provide an overview of the archaeal extremophilic microorganisms such as thermopiles, acidophiles, halophiles which have potential applications in the field of bioremediation of environmental pollutants, including hydrocarbons, heavy metals, pesticides, petroleum and wastewater treatments.

Combination chemotherapy can increase treatment efficacy and suppress drug resistance. Knowledge of how to engineer rational, mechanism-based drug combinations, however, remains lacking. Although studies of drug activity have historically focused on the primary drug–target interaction, growing evidence has emphasized the importance of the subsequent consequences of this interaction. Bedaquiline (BDQ) is the first new drug for tuberculosis (TB) approved in more than 40 y, and a species-selective inhibitor of the Mycobacterium tuberculosis (Mtb) ATP synthase. Curiously, BDQ-mediated killing of Mtb lags significantly behind its inhibition of ATP synthase, indicating a mode of action more complex than the isolated reduction of ATP pools. Here, we report that BDQ-mediated inhibition of Mtb’s ATP synthase triggers a complex metabolic response indicative of a specific hierarchy of ATP-dependent reactions. We identify glutamine synthetase (GS) as an enzyme whose activity is most responsive to changes in ATP levels. Chemical supplementation with exogenous glutamine failed to affect BDQ’s antimycobacterial activity. However, further inhibition of Mtb’s GS synergized with and accelerated the onset of BDQ-mediated killing, identifying Mtb’s glutamine synthetase as a collateral, rather than directly antimycobacterial, metabolic vulnerability of BDQ. These findings reveal a previously unappreciated physiologic specificity of ATP and a facet of mode-of-action biology we term collateral vulnerability, knowledge of which has the potential to inform the development of rational, mechanism-based drug combinations.

The heart of the present day MRI scanners is a superconducting magnet producing the required central field. A 1.5 T multicoil magnet with ±5.5 ppm field homogeneity in 45 cm field of view (FOV) is designed. These coils will operate at an average current density of 130 A/mm 2 . The magnet bobbin will be made of 5083 aluminium alloy, while the winding pack of the magnet will be a composite structure which will consist of Nb-Ti, copper, epoxy and insulations. The winding pretension, thermal strains, due to cooling, and Lorentz forces contribute to the overall stress, which during operation can cause deformation of the magnet. To design a structurally sound and stable magnet system, it is critical to evaluate the stresses that are generated in the magnet during winding, cool down and operation. This paper discusses the stresses generated on the magnet and deformations produced due to the forces acting on the coils. The effect of deformation on the field homogeneity and the influence of winding tension on the overall operational stress are also studied. The von-Mises stress during the operation is found to be 40 MPa along the median line. The deformations of the magnet due to operational stresses increased the field homogeneity to ±85 ppm in the FOV.

RNA is a unique bio-molecule as it can act as (i) genetic messenger like DNA, (ii) relay system for DNA, as well as perform (iii) catalysis like proteins. The versatility of this molecule has supported the concept of the RNA world. A new dimension to our understanding of the role of RNA emerged from the observation of the involvement of RNA in the regulation of genome organization and gene expression. In this chapter, the focus is on the regulatory RNA in the context of bacterial lifestyle and its interaction with the host. In the era of microbiome, our understanding of the host-microbe interaction has changed radically. We have come from the time where bacteria were synonymous to pathogen to the time where bacteria are considered an integral part of a healthy host. Apart from healthy microbiota, bacterial pathogens also have strategies to circumvent defense mechanisms of host cells. The adaptation inside the host requires extensive physiological rewiring and cellular regulatory machinery plays a critical role in responding to the microenvironment. In the following section, we will discuss the role of regulatory RNAs in bacterial lifestyle and the host defense system.

GaxZn1-xO thin films with varying Ga fraction within the solubility limit were irradiated with high-energy heavy ions to induce electronic excitations. The films show good transmittance in the visible region and a reduction of about 20% in transmittance was observed for irradiated films at higher ion fluences. The Urbach energy was estimated and showed an augmenting response upon increase in doping fraction and ion irradiation, this divulges an enhancement of localized states in the bandgap or disorder in the films. The evolution of such localized states plays a vital role in charge transport and thus the temperature dependent electrical conductivity of irradiated thin films was studied to elucidate the dominant conduction mechanisms. The detailed analysis unfolds that in the high-temperature regime (180 K

A major impediment to developing effective antimicrobials against Gram-negative bacteria like Salmonella is the ability of the bacteria to develop resistance against existing antibiotics and the inability of the antimicrobials to clear the intracellular bacteria residing in the gastrointestinal tract. As the critical balance of charge and hydrophobicity is required for effective membrane-targeting antimicrobials without causing any toxicity to mammalian cells, herein we report the synthesis and antibacterial properties of cholic acid-derived amphiphiles conjugated with alkyl chains of varied hydrophobicity. Relative to other hydrophobic counterparts, a compound with hexyl chain (6) acted as an effective antimicrobial against different Gram-negative bacteria. Apart from its ability to permeate the outer and inner membranes of bacteria; compound 6 can cross the cellular and lysosomal barriers of epithelial cells and macrophages and kill the facultative intracellular bacteria without disrupting the mammalian cell membranes. Oral delivery of compound 6 was able to clear the Salmonella-mediated gut infection and inflammation, and was able to combat persistent, stationary, and multi-drug-resistant clinical strains. Therefore, our study reveals the ability of cholic acid-derived amphiphiles to clear intracellular bacteria and Salmonella-mediated gut infection and inflammation.

Living organisms have developed specific defence mechanisms to counteract hostile environmental conditions. Alkylation stress response mechanisms also occur in Mycobacterium tuberculosis (MTB) the pathogen responsible for tuberculosis. The effect of alkylating agents on the cellular growth of MTB was investigated using methyl methanesulfonate (MMS) as methyl donor demonstrating that limited doses of alkylating agents might affect MTB cell viability . A global investigation of Mycobacterium smegmatis response to alkylating stress was then pursued by differential proteomics to identify the most affected cellular pathways. Quantitative analysis of proteomic profiles demonstrated that most of the proteins upregulated in the presence of alkylating agents are involved in biofilm formation and/or cell wall biosynthesis. Tailored experiments confirmed that under stress conditions M. smegmatis elicits physical defence mechanisms by increasing biofilm formation. Among the upregulated proteins, we identified the GlmU bifunctional enzyme as a possible factor involved in biofilm production. Experiments with both conditional deletion and overexpressing glmU mutants demonstrated that down regulation of GlmU decreased M. smegmatis capabilities to produce biofilm whereas overexpression of the enzyme increased biofilm formation. These results were supported by inhibition of GlmU acetyltransferase activity with two different inhibitors, suggesting the involvement of this enzyme in the M. smegmatis defence mechanisms.

The highly persistent nature of Mycobacterium tuberculosis can be attributed to its lipophilic cell wall which acts as a major barrier in the process of drug discovery against tuberculosis. Glutamine synthetase plays a major role in nitrogen metabolism and cell wall biosynthesis of pathogenic mycobacteria. The current review focuses on the structural and functional aspects of Mtb glutamine synthetase and an overview of its reported inhibitors till date. Also in the present study, we employed a computational structure based drug design protocol for identifying novel inhibitors against Mtb glutamine synthetase (MtbGS). A total of 12 hits were identified based on e-pharmacophore related search and virtual screening, which were further tested for their in vitro MtbGS inhibitory activity. Three compounds (compound 6, 1 and 12) were found with IC50 less than 5#181;M, of which compound 6 being top active with IC50 of 2.124#181;M. Differential scanning fluorimetry studies were employed so as to measure the thermal stability of the protein complexed with the most active compound. Also the protein complexes with top three active compounds were subjected for molecular dynamics simulations to study their binding pattern and stabilization effect. The solvation free energies were also determined for these compounds, undertaking free energy perturbation studies, which can be used further for lead optimization in the process of anti-tubercular drug discovery targeting Mtb glutamine synthetase.

Mycobacterium tuberculosis (Mtb) topoisomerase I (Topo I), involved in the relaxation of negatively supercoiled DNA, plays an important role in the viability of pathogen Mtb. Being one of the most significant enzymes; it also takes part in crucial biological pathways such as transcription and replication of the pathogen. The present study aims at the development of Mtb Topo I 3D protein structure which in turn was employed for the virtual screening of compound libraries in a process of identification of a hit molecule. The identified hit, hydroxycamptothecin, was active at 6.25 μM which was further derivatized synthetically into fifteen novel analogues. Among these, four compounds (3b, 3g, 3h and 3l) emerged to be active displaying IC50 values ranging from 2.9 to 9.3 μM against Mtb Topo I and were non-cytotoxic at 25 μM. These four compounds also proved their efficacy when tested against active, dormant and resistant forms of Mtb. The most potent inhibitor 3b was screened for in vivo anti-mycobacterial activity using zebrafish model and was found to be more effective when compared to first line anti-tubercular drugs, isoniazid and rifampicin. The binding affinity of this compound towards Mtb Topo I was analyzed by differential scanning fluorimetry which resulted in a positive shift in melting temperature when compared to the native protein thereby proving its stabilization effect over protein.

DNA gyrase of Mycobacterium tuberculosis (MTB) is a type II topoisomerase that ensures the regulation of DNA topology and has been genetically demonstrated to be a bactericidal drug target. We present the discovery and optimisation of a novel series of mycobacterial DNA gyrase inhibitors with a high degree of specificity towards the mycobacterial ATPase domain. Compound 5-fluoro-1-(2-(4-(4-(trifluoromethyl)benzylamino)piperidin-1-yl)ethyl)indoline-2,3-dione (17) emerged as the most potent lead, exhibiting inhibition of MTB DNA gyrase supercoiling assay with an IC50 (50% inhibitory concentration) of 3.6 ± 0.16 μM, a Mycobacterium smegmatis GyrB IC50 of 10.6 ± 0.6 μM, and MTB minimum inhibitory concentrations of 6.95 μM and 10 μM against drug-sensitive (MTB H37Rv) and extensively drug-resistant strains, respectively. Furthermore, the compounds did not show any signs of cardiotoxicity in zebrafish ether-à-go-go-related gene (zERG), and hence constitute a major breakthrough among the otherwise cardiotoxic N-linked aminopiperidine analogues.

Mycobacterium tuberculosis (MTB) the etiological agent of tuberculosis (TB) survives in the human host for decades evading the immune system in a latent or persistent state. The Rv2780 (ald) gene that codes for L-alanine dehydrogenase (L-AlaDH) enzyme catalyzes reversible oxidative deamination of L-alanine to pyruvate and is overexpressed under hypoxic and nutrient starvation conditions in MTB. At present, as there is no suitable drug available to treat dormant tuberculosis; it is essential to identify drug candidates that could potentially treat dormant TB. Availability of crystal structure of MTB L-AlaDH bound with co-factor NAD+ facilitated us to employ structure-based virtual screening approach to obtain new hits from a commercial library of Asinex database using energy-optimized pharmacophore modeling. The resulting pharmacophore consisted of three hydrogen bond donor sites (D) and two hydrogen bond acceptor sites (A). The database compounds with a fitness score more than 1.0 were further subjected to Glide high-throughput virtual screening and docking. Thus, we report the identification of best five hits based on structure-based design and their in vitro enzymatic inhibition studies revealed IC₅₀ values in the range of 35-80 μM.

The paper presents the analysis of stresses due to winding tension in a 1.5 T MRI magnet with a clear bore of ∼1 m and an outer diameter of ∼1.8 m. The magnet has four pairs of symmetric coils arranged over a length of ∼1.5 m. The stringent requirement of field homogeneity makes it critical to design a structurally stable magnet system. It is essential to evaluate the 3-dimensional stresses that would be generated in the magnet during winding, cool down and operation. The bobbin structure also has to be designed so as to reduce the relative movements of theeight superconducting coils, which otherwise can adversely affect the field homogeneity at the Field of View (FOV). The bobbin will be made of aluminium 5083 alloy, while the magnet winding will be a composite structure which consists of NbTi, copper and polyester insulation. The paper discusses the stress distribution over the aluminium bobbin and the coil caused due to winding tension applied during magnet winding. The article also discusses the element death and birth method in FEA to accurately simulate the winding process.

Mycobacterium tuberculosis (MTB) has remarkable ability to persist in the human host and causes latent infection in one third of the world population. Currently available tuberculosis (TB) drugs while effective in killing actively growing MTB, is largely ineffective in killing persistent or latent MTB. Lysine-ɛ aminotransferase (LAT) enzyme is reported to be highly up-regulated (41.86 times) in in vitro models of TB designed to mimic the latent stage. Hence inhibition of this MTB LAT seems attractive for developing novel drugs against latent TB. In the present study, crystal structure of the MTB LAT bound to substrate was used as a framework for structure-based design utilizing database compounds to identify novel thiazole derivative as LAT inhibitors. Thirty six compounds were synthesized and evaluated in vitro for their ability to inhibit LAT, in vitro activity against latent MTB, in vivo activity using Mycobacterium marinum infected zebra fish and cytotoxicity as steps toward the derivation of structure-activity relationship (SAR) for lead optimization. Compound 4-methoxy-2-(pyridin-4-yl)thiazole-5-carboxylic acid (24) emerged as the most promising lead with an IC50 of 1.22 ± 0.85 μM against LAT and showed 2.8 log reduction against nutrient starved MTB, with little cytotoxicity at a higher concentration (>50 μM). It also exhibited 1.5 log reduction of M. marinum load in in vivo zebra fish model at 10 mg/kg.

3-Dehydroquinate dehydratase (DHQase), the third enzyme of the shikimate pathway, catalyzes the reversible reaction of 3-dehydroquinate into 3-dehydroshikimate. The aim of the present study was to identify new drug-like molecules as inhibitors for Mycobacterium tuberculosis DHQase employing structure-based pharmacophore modeling technique using an in house database consisting of about 2500 small molecules. Further the pharmacophore models were validated using enrichment calculations, and finally three models were employed for high-throughput virtual screening and docking to identify novel small molecules as DHQase inhibitors. Five compounds were identified, out of which, one molecule (Lead 1) showed 58% inhibition at 50μ M concentration in the Mtb DHQase assay. Chemical derivatives of the Lead 1 when tested evolved top two hits with IC50s of 17.1 and 31.5 μM as well as MIC values of 25 and 6.25 μg/mL respectively and no cytotoxicity up to 100 μM concentration.

Persistent nature of Mycobacterium tuberculosis is one of the major factors which make the drug development process monotonous against this organism. The highly lipophilic cell wall, which constituting outer mycolic acid and inner peptidoglycan layers, acts as a barrier for the drugs to enter the bacteria. The rigidity of the cell wall is imparted by the peptidoglycan layer, which is covalently linked to mycolic acid by arabinogalactan. Uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) serves as the starting material in the biosynthesis of this peptidoglycan layers. This UDP-GlcNAc is synthesized by N-acetylglucosamine-1-phosphate uridyltransferase (GlmU(Mtb)), a bi-functional enzyme with two functional sites, acetyltransferase site and uridyltransferase site. Here, we report design and screening of nine inhibitors against UTP and NAcGlc-1-P of uridyltransferase active site of glmU(Mtb). Compound 4 was showing good inhibition and was selected for further analysis. The isothermal titration calorimetry (ITC) experiments showed the binding energy pattern of compound 4 to the uridyltransferase active site is similar to that of substrate UTP. In silico molecular dynamics (MD) simulation studies, for compound 4, carried out for 10 ns showed the protein-compound complex to be stable throughout the simulation with relative rmsd in acceptable range. Hence, these compounds can serve as a starting point in the drug discovery processes against Mycobacterium tuberculosis.

A series of ethyl-4-(4-((substituted benzyl)amino)piperidin-1-yl)-2-(phenyl/pyridyl)thiazole-5-carboxylates was designed by molecular hybridization and synthesized from aryl thioamides in five steps. The compounds were evaluated for their in vitro Mycobacterium smegmatis (MS) GyrB ATPase assay, Mycobacterium tuberculosis (MTB) DNA gyrase super coiling assay, antituberculosis activity and cytotoxicity. Among the twenty four compounds studied, ethyl-4-(4-((4-fluorobenzyl)amino)piperidin-1-yl)-2-phenylthiazole-5-carboxylate (14) was found to be the promising compound which showed activity against all test with MS GyrB IC50 of 24.0 ± 2.1 μM, 79% inhibition of MTB DNA gyrase at 50 μM, MTB MIC of 28.44 μM, and not cytotoxic at 50 μM.

This article is a review of the therapeutic significance of arformoterol tartrate, a new generation 2 adrenergic agonist bronchodilator available in a nebulized form. Arformoterol is well absorbed through the lungs when administered via a standard jet nebulizer and is useful in long-term maintenance therapy of bronchoconstriction in chronic obstructive pulmonary disease (COPD). Much clinical evidence suggest the potentially enhanced efficacy of this drug in the treatment of COPD including chronic bronchitis and emphysema. Various hyphenated analytical methodologies have also been employed for the determination and quantification of arformoterol. This review provides an updated account on the pharmacology, pharmacokinetics, clinical studies, analytical techniques, drug-drug interactions, contraindications, and therapeutic applications of arformoterol tartrate. Keywords : Arformoterol tartrate, Adrenergic agonist, Bronchodilator, COPD Tropical Journal of Pharmaceutical Research December 2010; 9 (6): 595-603