ORCID Profile
0000-0002-4315-390X
Current Organisations
UNSW Sydney
,
University of Exeter
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Publisher: Public Library of Science (PLoS)
Date: 26-07-2019
Publisher: American Chemical Society (ACS)
Date: 02-10-2013
DOI: 10.1021/LA403067H
Abstract: We demonstrate the creation of Ag-based bimetallic platonic Janus nanostructures by confining galvanic replacement reaction at a nanoscale interface on highly symmetrical nanostructures such as Ag nanocubes and nanooctahedra using reactive microcontact printing (μCP). The extent of galvanic replacement reaction can be controlled kinetically to derive Janus nanostructures with Au nanodots deposited on either one or multiple facets of Ag nanocubes. The selective deposition of Au dots on a single facet of Ag nanocubes breaks the cubic symmetry and brings about unique and anisotropic plasmonic responses. High-resolution cathodoluminescence hyperspectral imaging of single Janus nanocube demonstrates that surface plasmon resonances corresponding to Au and Ag can be excited at different spots on one Janus nanocube. In addition, we demonstrate the fabrication of alternating Janus/non-Janus segments on 2D Ag nanowires by using a line-patterned polydimethylsiloxane (PDMS) st for galvanic replacement. Aside from Au, Pt and Pd can also be selectively deposited onto Ag nanocubes. These Janus nanostructures may find important applications in the field of plasmon-enhanced catalysis.
Publisher: Springer Science and Business Media LLC
Date: 16-09-2019
DOI: 10.1038/S41598-019-49738-1
Abstract: Hemoperfusion (HP) is one of the important treatment modalities in extracorporeal therapy for patients with acute intoxication. Its use has declined during the past 20 years despite its efficacy, because of its side effects, especially an increased risk of bleeding. Mechanisms of hemostasis impairment have not been clearly elucidated and studies demonstrating the mechanism are lacking. It is not clear which step of the hemostatic process is impaired during HP, and whether it leads to an increased risk of bleeding. We performed both in vivo and in vitro studies to elucidate the mechanism of impairment in the hemostatic process. In patients with acute pesticide intoxication who underwent HP, the platelet count decreased rapidly during the first 30 minutes from 242.4 ± 57.7 × 10 3 /μL to 184.8 ± 49.6 × 10 3 /μL, then gradually decreased even lower to 145.4 ± 61.2 × 10 3 /μL over time (p 0.001). As markers of platelet activation, platelet distribution width increased continuously during HP from 41.98 ± 9.28% to 47.69 ± 11.18% (p 0.05), however, mean platelet volume did not show significant change. In scanning electron microscopy, activated platelets adhered to modified charcoal were observed, and delayed closure time after HP in PFA-100 test suggested platelet dysfunction occurred during HP. To confirm these conflicting results, changes of glycoprotein expression on the platelet surface were evaluated when platelets were exposed to modified charcoal in vitro . Platelet expression of CD61, fibrinogen receptor, significantly decreased from 95.2 ± 0.9% to 73.9 ± 1.6%, while those expressing CD42b, von Willebrand factor receptor, did not show significant change. However, platelet expression of CD49b, collagen receptor, significantly increased from 24.6 ± 0.7% to 51.9 ± 2.3%. Thrombin-antithrombin complex, a marker for thrombin generation, appeared to decrease, however, it was not statistically significant. Fibrin degradation products and d-dimers, markers for fibrinolysis, increased significantly during HP. Taken together, our data suggests that hemoperfusion leads to impairment of platelet aggregation with incomplete platelet activation, which was associated with reduced thrombin generation, accompanied by increased fibrinolysis.
Publisher: Public Library of Science (PLoS)
Date: 31-05-2022
DOI: 10.1371/JOURNAL.PBIO.3001648
Abstract: The continued spread of drug-resistant tuberculosis is one of the most pressing and complex challenges facing tuberculosis management worldwide. Therefore, developing a new class of drugs is necessary and urgently needed to cope with the increasing threat of drug-resistant tuberculosis. This study aims to discover a potential new class of tuberculosis drug candidates different from existing tuberculosis drugs. By screening a library of compounds, methyl (S)-1-((3-alkoxy-6,7-dimethoxyphenanthren-9-yl)methyl)-5-oxopyrrolidine-2-carboxylate (PP) derivatives with antitubercular activity were discovered. MIC ranges for PP1S, PP2S, and PP3S against clinically isolated drug-resistant Mycobacterium tuberculosis strains were 0.78 to 3.13, 0.19 to 1.56, and 0.78 to 6.25 μg/ml, respectively. PPs demonstrated antitubercular activities in macrophage and tuberculosis mouse models, showing no detectable toxicity in all assays tested. PPs specifically inhibited M . tuberculosis without significantly changing the intestinal microbiome in mice. Mutants selected in vitro suggest that the drug targets the PE-PGRS57, which has been found only in the genomes of the M . tuberculosis complex, highlighting the specificity and safety potency of this compound. As PPs show an excellent safety profile and highly selective toxicity specific to M . tuberculosis , PPs are considered a promising new candidate for the treatment of drug-resistant tuberculosis while maintaining microbiome homeostasis.
Publisher: American Chemical Society (ACS)
Date: 07-08-2013
DOI: 10.1021/JP4063077
Publisher: Oxford University Press (OUP)
Date: 2023
Abstract: The bacterial flagellar motor (BFM) is a rotary nanomachine powered by the translocation of ions across the inner membrane through the stator complex. The stator complex consists of two membrane proteins: MotA and MotB (in H+-powered motors), or PomA and PomB (in Na+-powered motors). In this study, we used ancestral sequence reconstruction (ASR) to probe which residues of MotA correlate with function and may have been conserved to preserve motor function. We reconstructed 10 ancestral sequences of MotA and found four of them were motile in combination with contemporary Escherichia coli MotB and in combination with our previously published functional ancestral MotBs. Sequence comparison between wild-type (WT) E. coli MotA and MotA-ASRs revealed 30 critical residues across multiple domains of MotA that were conserved among all motile stator units. These conserved residues included pore-facing, cytoplasm-facing, and MotA–MotA intermolecular facing sites. Overall, this work demonstrates the role of ASR in assessing conserved variable residues in a subunit of a molecular complex.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.IJANTIMICAG.2019.02.013
Abstract: Due to the emergence of multidrug-resistant and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis, new antituberculosis drugs are urgently required to improve the efficacy of current tuberculosis (TB) treatment. To achieve this goal, ca. 1000 chemical compounds were screened for potential antimycobacterial activity, among which methyl 5-(2-diethylaminoethoxy)-7,12-dioxo-7,12 dihydrodinaphtho[1,2-b ',3'-d]furan-6-carboxylate (DNF-3) showed strong activity against all of the tested drug-susceptible and -resistant M. tuberculosis strains, with 50% minimum inhibitory concentrations (MIC
Publisher: American Chemical Society (ACS)
Date: 23-10-2017
Publisher: Briefland
Date: 24-10-2022
DOI: 10.5812/JJM-129482
Abstract: Background: The rise of antibiotic-resistant Mycobacterium tuberculosis strains has accelerated the hunt for novel drugs for tuberculosis (TB). Objectives: This study identified a novel compound with strong anti-TB efficacy against several resistant M. tuberculosis strains from a chemical library of naphthoquinone derivatives. Methods: The identified chemical was designated as MDN-6 (methyl-1,4-bis(2-(diethylamino)ethoxy)-2-naphthoate). Results: It significantly inhibited all the tested Mycobacterium strains, including 24 clinically isolated resistant strains. The minimum inhibitory concentrations of MDN-6 were between 0.02 and 25 g/mL. It also had partially synergistic activity against extensively drug-resistant M. tuberculosis when coupled with rif icin and streptomycin. Additionally, MDN-6 demonstrated a superior post-antibiotic effect over isoniazid and exhibited comparable inhibitory efficacy against Mycobacterium marinum and Mycobacterium kansasii. Besides the antimicrobial effect, MDN-6 had a 50% lethal dosage (LD50) of 279.1 mg/kg in female BALB/c mice. Conclusions: MDN-6 is a promising anti-TB therapeutic candidate against drug-resistant M. tuberculosis. However, further investigation is necessary to elucidate the action mechanism and assess the drug’s in vivo therapeutic potential.
Publisher: American Chemical Society (ACS)
Date: 24-04-2014
DOI: 10.1021/JA501786S
Abstract: Single-phase Cu2ZnSnS4 (CZTS) is an essential prerequisite toward a high-efficiency thin-film solar cell device. Herein, the selective phase formation of single-phase CZTS nanoparticles by ligand control is reported. Surface-enhanced Raman scattering (SERS) spectroscopy is demonstrated for the first time as a characterization tool for nanoparticles to differentiate the mixed compositional phase (e.g., CZTS, CTS, and ZnS), which cannot be distinguished by X-ray diffraction. Due to the superior selectivity and sensitivity of SERS, the growth mechanism of CZTS nanoparticle formation by hot injection is revealed to involve three growth steps. First, it starts with nucleation of Cu(2-x)S nanoparticles, followed by diffusion of Sn(4+) into Cu(2-x)S nanoparticles to form the Cu3SnS4 (CTS) phase and diffusion of Zn(2+) into CTS nanoparticles to form the CZTS phase. In addition, it is revealed that single-phase CZTS nanoparticles can be obtained via balancing the rate of CTS phase formation and diffusion of Zn(2+) into the CTS phase. We demonstrate that this balance can be achieved by 1 mL of thiol with Cu(OAc)2, Sn(OAc)4, and Zn(acac)2 metal salts to synthesize the CZTS phase without the presence of a detectable binary/ternary phase with SERS.
Publisher: Future Science Ltd
Date: 02-2021
Abstract: Aim: Tuberculosis is the leading cause of mortality among infectious diseases worldwide. Finding a new competent anti tubercular therapy is essential. Materials & methods: We screened thousands of compounds and evaluated their efficacy against Mycobacterium tuberculosis. Results: Initially, 2-nitronaphtho[2,3-b]benzofuran-6,11-dione was active against M. tuberculosis. Next, among 15 newly synthesized derivatives, BNF15 showed promising effect against all drug-sensitive and drug-resistant M. tuberculosis (MIC: 0.02–0.78 μg/ml). BNF15 effectively killed intracellular M. tuberculosis and nontuberculous mycobacteria. BNF15 exhibited a prolonged post antibiotic effect superior to isoniazid, streptomycin, and ethambutol and synergistic interaction with rif icin. In acute oral toxicity test, BNF15 did not show toxic effect at a concentration up to 2000 mg/kg. Conclusion: These results highlight the perspective of BNF15 to treat drug-resistant M. tuberculosis.
Publisher: Cold Spring Harbor Laboratory
Date: 13-04-2021
DOI: 10.1101/2021.04.13.439105
Abstract: The bacterial flagellar motor (BFM) is a protein complex that confers motility to cells and contributes to survival and virulence. The BFM consists of stators that are ion-selective membrane protein complexes and a rotor that directly connects to a large filament, acting as a propeller. The stator complexes couple ion transit across the membrane to torque that drives rotation of the motor. The most common ion gradients that drive BFM rotation are protons (H + ) and sodium ions (Na + ). The sodium-powered stators, like those in the PomAPomB stator complex of Vibrio spp, can be inhibited by sodium channel inhibitors, in particular, by phenamil, a potent and widely used inhibitor. However, relatively few new sodium-motility inhibitors have been described since the discovery of phenamil. In this study, we characterised two possible motility inhibitors HM2-16F and BB2-50F from a small library of previously reported amiloride derivatives. We used three approaches: effect on rotation of tethered cells, effect on free swimming bacteria and effect on rotation of marker beads. We showed that both HM2-16F and BB2-50F stopped rotation of tethered cells driven by Na + motors comparable to phenamil at matching concentrations, and could also stop rotation of tethered cells driven by H + motors. Bead measurements in presence and absence of stators confirmed that the compounds did not inhibit rotation via direct association with the stator, in contrast to the established mode of action of phenamil. Overall, HM2-16F and BB2-50F stopped swimming in both Na + and H + stator types, and in pathogenic and non-pathogenic strains. Here we characterised two novel amiloride derivatives in the search for antimicrobial compounds that target bacterial motility. Our two compounds were shown to inhibit flagellar motility at 10 μM across multiple strains, from non-pathogenic E. coli with flagellar rotation driven by proton or chimeric sodium-powered stators, to proton-powered pathogenic E. coli (EHEC/UPEC) and lastly in sodium-powered Vibrio alginolyticus . Broad anti-motility compounds such as these are important tools in our efforts control virulence of pathogens in health and agricultural settings.
Publisher: American Chemical Society (ACS)
Date: 07-07-2016
Publisher: Wiley
Date: 07-07-2016
Abstract: Controlling sub-10 nm ligament sizes and open-shell structure in nanoporous gold (NPG) to achieve strained lattice is critical in enhancing catalytic activity, but it remains a challenge due to poor control of reaction kinetics in conventional dealloying approach. Herein, a ligament size-controlled synthesis of open-shell NPG bowls (NPGB) through hetero-epitaxial growth of NPGB on AgCl is reported. The ligament size in NPGB is controlled from 6 to 46 nm by varying the hydroquinone to HAuCl4 ratio. The Williamson-Hall analysis demonstrates a higher lattice strain in smaller ligament size. In particular, NPGB with 6 nm (NPGB 6) ligament size possess the highest strain of 15.4 × 10(-3) , which is nearly twice of conventional 2D NPG sheets (≈8.8 × 10(-3) ). The presence of high surface energy facets in NPGBs is also envisaged. The best electrocatalytic activity toward methanol oxidation is observed in NPGB 6 (27.8 μA μg(-1) ), which is ≈9-fold and 3-fold higher than 8 nm solid Au nanoparticles, and conventional NPG sheets. The excellent catalytic activity in NPGB 6 is attributed to the open-shell structure, lattice strain, and higher electro-active surface area, allowing efficient exposure of catalytic active sites to facilitate the methanol oxidation. The results offer a potential strategy for designing next generation electrocatalysts.
Publisher: Korean Society for Microbiology and Biotechnology
Date: 28-01-2022
Publisher: Public Library of Science (PLoS)
Date: 26-12-2019
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.PUPT.2017.08.003
Abstract: This study explores the antitubercular activity of α-viniferin, a bioactive phytochemical compound obtained from Carex humilis. α-Viniferin was active against both drug-susceptible and -resistant strains of Mycobacterium tuberculosis at MIC
Publisher: American Chemical Society (ACS)
Date: 25-09-2012
DOI: 10.1021/LA302795R
Abstract: The effective number of surface-enhanced Raman spectroscopy (SERS) active hot spots on plasmonic nanostructures is the most crucial factor in ensuring high sensitivity in SERS sensing platform. Here we demonstrate a chemical etching method to increase the surface roughness of one-dimensional Ag nanowires, targeted at creating more SERS active hot spots along Ag nanowire's longitudinal axis for increased SERS detection sensitivity. Silver nanowires were first synthesized by the conventional polyol method and then subjected to chemical etching by NH(4)OH and H(2)O(2) mixture. The surfaces of silver nanowires were anisotropically etched off to create miniature "beads on a string" features with increased surface roughness while their crystallinity was preserved. Mapping of single-nanowire SERS measurements showed that the chemical etching method has overcome the limitation of conventional one-dimensional Ag nanowires with limited SERS active area at the tips to produce etched Ag nanowires with an increase in Raman hot spots and polarization-independent SERS signals across tens of micrometers length scale.
Publisher: American Society for Microbiology
Date: 25-10-2021
DOI: 10.1128/JB.00367-21
Abstract: Here, we characterized two novel amiloride derivatives in the search for antimicrobial compounds that target bacterial motility. Our two compounds were shown to inhibit flagellar motility at 10 μM across multiple strains: from nonpathogenic Escherichia coli with flagellar rotation driven by proton or chimeric sodium-powered stators, to proton-powered pathogenic E. coli (enterohemorrhagic E. coli or uropathogenic E. coli [EHEC or UPEC, respectively]), and finally, sodium-powered Vibrio alginolyticus .
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.PHYMED.2018.04.029
Abstract: Tuberculosis is a very serious infectious disease that threatens humanity, and the emergence of multidrug-resistant (MDR), extensively drug-resistant (XDR) strains resistant to drugs suggests that new drug development is urgent. In order to develop new tuberculosis drug, we have conducted in vitro anti-tubercular tests on thousands of plant-derived substances and finally found collinin extracted from the leaves of Zanthoxylum schinifolium, which has an excellent anti-tuberculosis effect. To isolate an anti-tubercular bioactive compound from the leaves of Z. schinifolium and evaluate whether this agent demonstrates any potential in vitro characteristics suitable for the development of future anti-tubercular drugs to treat MDR and XDR Mycobacterium tuberculosis. The methanolic extracts of the leaves of Z. schinifolium were subjected to bioassay-guided fractionation against M. tuberculosis using a microbial cell viability assay. In addition, following cell cytotoxicity assay, an intracellular anti-mycobacterial activity of the most active anti-tubercular compound was investigated after it was purified. The active compound with anti-tubercular activity isolated from leaves of Z. schinifolium was identified as a collinin. The extracted collinin showed anti-tubercular activity against both drug-susceptible and -resistant strains of M. tuberculosis at 50% minimum inhibitory concentrations (MIC Collinin extracted from the leaves of Z. schinifolium significantly inhibits the growth of MDR and XDR M. tuberculosis in the culture broth. In addition, it also inhibits the growth of intracellular drug-susceptible and drug-resistant tuberculosis in Raw264.7 and A549 cells. To our knowledge, this is the first report on the in vitro anti-tubercular activity of collinin, and our data suggest collinin as a potential drug to treat drug-resistant tuberculosis. Further studies are warranted to assess the in vivo efficacy and therapeutic potential of collinin.
Publisher: Wiley
Date: 27-07-2020
Abstract: The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d‐band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of % with high ammonia yield rate of μg mg cat −1 h −1 under ambient conditions. The strategy lowers electrocatalyst d‐band position to weaken H adsorption and concurrently creates electron‐deficient sites to kinetically drive NRR by promoting catalyst–N 2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by ‐fold compared to without ZIF (ca. 1 %). The Pt/Au‐N ZIF interaction is key to enable strong N 2 adsorption over H atom.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3NR06316J
Abstract: Ag octahedron nanoparticles are assembled with graphene oxide (GO) sheets to form Ag octahedron@GO hybrids. Owing to the excellent chemical enhancement of GO, single particle SERS demonstrates an enhancement factor of 9 × 10 5 , which is twice as large as that of a pure octahedron.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.YRTPH.2018.02.011
Abstract: The infectious disease tuberculosis remains a serious global health issue and is responsible for nearly 1.8 million deaths every year. In our previous study, DFC-2 was confirmed to show anti-tubercular activity against drug-susceptible and drug-resistant strains of Mycobacterium tuberculosis. To support the safety-in-use of DFC-2 as an anti-tubercular drug, DFC-2 was tested via single- and 28-day repeated-dose oral toxicity study and mutagenicity assays. In the oral toxicity study, a single oral dose of DFC-2 at 2000 mg/kg did not produce deaths or abnormal lesions in the internal organs of rats. The results of a 28-day orally repeated dose of DFC-2 did not show treatment-related deaths or obvious toxicity symptoms in the animals treated with a dose of 300 mg/kg/day during the experimental period. Therefore, the no-observed-adverse-effect level (NOAEL) of DFC-2 was determined as 300 mg/kg/day for both male and female rats. In addition, DFC-2 showed no genetic toxicity in in vitro bacterial reverse mutation test, in vitro chromosomal aberration test, and in vivo mouse bone marrow micronucleus formation test. These results indicate that DFC-2 is a promising anti-tubercular drug candidate with a favorable safety profile.
Publisher: Springer Science and Business Media LLC
Date: 17-09-2014
DOI: 10.1038/NCOMMS5947
Abstract: Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.
Publisher: Springer Science and Business Media LLC
Date: 12-01-2021
DOI: 10.1038/S41598-020-80227-Y
Abstract: The emergence of multi-drug resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis creates the urgency for new anti-tuberculosis drugs to improve the efficiency of current tuberculosis treatment. In the search for a new potential tuberculosis drug, we synthesized an isoindole based chemical library and screened a potential candidate with significant anti-tuberculosis activity. The compound named 2-hydroxy-4-(4-nitro-1,3-dioxoisoindolin-2-yl) benzoic acid (IDD-B40) showed strong activity against all the tested drug-susceptible and drug-resistant strains of M. tuberculosis, with the 50% minimum inhibitory concentrations (MIC 50 ) of 0.39 μg/ml both in culture broth and inside Raw 264.7 cells. Also, IDD-B40, in combination with rif icin, exhibited a direct synergistic effect against both XDR and H37Rv M. tuberculosis . Besides, IDD-B40 showed a better post-antibiotic effect (PAE) than did some first-line drugs and showed no significant cytotoxicity to any cell line tested, with a selectivity index of ≥ 128. Although IDD-B40 showed a result similar to isoniazid in the preliminary mycolic acid inhibition assay, it did not exhibit any effect against other mycolic acid-producing nontuberculous mycobacterial strains (NTM), and different non-mycobacterial pathogenic strains, so further studies are required to confirm the mode of action of IDD-B40. Considering its results against M. tuberculosis , IDD-B40 is a potential anti-tuberculosis drug candidate. However, further studies are required to evaluate its potential in vivo effect and therapeutic potential.
Publisher: Wiley
Date: 22-07-2014
Abstract: A major challenge in plasmonic hot spot fabrication is to efficiently increase the hot spot volumes on single metal nanoparticles to generate stronger signals in plasmon-enhanced applications. Here, the synthesis of designer nanoparticles, where plasmonic-active Au nanodots are selectively deposited onto the edge/tip hot spot regions of Ag nanoparticles, is demonstrated using a two-step seed-mediated precision synthesis approach. Such a "hot spots over hot spots" strategy leads to an efficient enhancement of the plasmonic hot spot volumes on single Ag nanoparticles. Through cathodoluminescence hyperspectral imaging of these selective edge gold-deposited Ag octahedron (SEGSO), the increase in the areas and emission intensities of hot spots on Ag octahedra are directly visualized after Au deposition. Single-particle surface-enhanced Raman scattering (SERS) measurements demonstrate 10-fold and 3-fold larger SERS enhancement factors of the SEGSO as compared to pure Ag octahedra and non-selective gold-deposited Ag octahedra (NSEGSO), respectively. The experimental results corroborate well with theoretical simulations, where the local electromagnetic field enhancement of our SEGSO particles is 15-fold and 1.3-fold stronger than pure Ag octahedra and facet-deposited particles, respectively. The growth mechanisms of such designer nanoparticles are also discussed together with a demonstration of the versatility of this synthetic protocol.
Publisher: American Chemical Society (ACS)
Date: 14-08-2017
DOI: 10.1021/JACS.7B04936
Abstract: We demonstrate a molecular-level observation of driving CO
Publisher: Korean Society for Microbiology and Biotechnology
Date: 28-11-2017
Abstract: DFC-2, a methyl 5-[2-(dimethylamino)ethoxy]-7,12-dioxo-7,12-dihydrodinaphtho[1,2-b:2',3'-d]furan-6-carboxylate, is reported to have antitubercular effects against
Publisher: Journal of Infection in Developing Countries
Date: 31-03-2019
DOI: 10.3855/JIDC.10768
Abstract: Introduction: In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure. This study was conducted to investigate the presence of antibiotic resistance, virulence factors and plasmid contents of E. coli strains isolated from sludge s les. Methodology: E. coli were isolated from human feces from closed pit latrines and identified by culture method. Antibiotic susceptibility patterns of the isolates were determined by Standard Kirby-Bauer disk diffusion method. Pathogenic genes and antibiotic resistance genes of ESBL producing isolates were determined by PCR assay. Results: Of the 34 s les tested, 76.5% contained E. coli. Of 72 E. coli isolates, 76.4% were resistant to at least one of the 12 antibiotics tested and 47.2% isolates were resistant to three or four classes of antibiotics. Around 18% isolates were extended spectrum β- lactamase producing and of them 6 were positive for blaTEM specific gene, 4 for blaCTX-M gene, 1 for blaOXA gene and 2 for both blaTEM and blaCTX-M genes. Moreover, among 72 isolates, 4.2% carried virulence genes of enterotoxigenic E. coli two isolates were positive for st and one was positive for both st and lt genes. In addition, 59.7% of the isolates contained plasmids (range 1.4 to 140 MDa) of which 19.5% isolates contained a single plasmid and 40.2% contained multiple plasmids. Conclusions: The presence of pathogenic, drug resistant E. coli in human sludge necessitates a regular surveillance before using as a biofertilizer.
Publisher: Wiley
Date: 17-08-2017
DOI: 10.1002/PTR.5890
Abstract: Responsible for nearly 1.5 million deaths every year, the infectious disease tuberculosis remains one of the most serious challenges to global health. The emergence of multidrug-resistant tuberculosis and, more recently, extensively drug-resistant tuberculosis poses a significant threat in our effort to control this epidemic. New drugs are urgently needed to combat the growing threat of antimicrobial resistance. To achieve this goal, we screened approximately 500 species of medicinal plant methanol extracts and their solvent partitioned fractions for potential inhibitors of Mycobacterium tuberculosis growth. Using microdilution screening, the ethyl acetate solvent partitioned fraction from the heartwood of Caesalpinia sappan exhibited strong antitubercular activity. We isolated the active compound and identified it as 3-deoxysappanchalcone. The extracted 3-deoxysappanchalcone possessed activity against both drug-susceptible and drug-resistant strains of M. tuberculosis at MIC
Publisher: Cold Spring Harbor Laboratory
Date: 18-10-2022
DOI: 10.1101/2022.10.17.512626
Abstract: The bacterial flagellar motor (BFM) is a rotary nanomachine powered by the translocation of ions across the inner membrane through the stator complex. The stator complex consists of two membrane proteins: MotA and MotB (in H + powered motors), or PomA and PomB (in Na + powered motors). In this study we used ancestral sequence reconstruction (ASR) to probe which residues of MotA correlate with function and may have been conserved to preserve motor function. We reconstructed ten ancestral sequences of MotA and found four of them were motile in combination with contemporary E. coli MotB and in combination with our previously published functional ancestral MotBs. Sequence comparison between wild-type (WT) E. coli MotA and MotA-ASRs revealed 30 critical residues across multiple domains of MotA that were conserved among all motile stator units. These conserved residues included pore-facing, cytoplasm-facing and MotA-MotA intermolecular facing sites. Overall, this work demonstrates the role of ASR in assessing conserved variable residues in a subunit of a molecular complex.
Publisher: Wiley
Date: 27-07-2020
Publisher: Frontiers Media SA
Date: 19-03-2021
Publisher: American Chemical Society (ACS)
Date: 12-11-2015
Publisher: Springer Science and Business Media LLC
Date: 25-05-2017
Publisher: Frontiers Media SA
Date: 23-12-2020
DOI: 10.3389/FMICB.2020.625837
Abstract: The bacterial flagellar motor (BFM) is a nanomachine that rotates the flagellum to propel many known bacteria. The BFM is powered by ion transit across the cell membrane through the stator complex, a membrane protein. Different bacteria use various ions to run their BFM, but the majority of BFMs are powered by either proton (H + ) or sodium (Na + ) ions. The transmembrane (TM) domain of the B-subunit of the stator complex is crucial for ion selectivity, as it forms the ion channel in complex with TM3 and TM4 of the A-subunit. In this study, we reconstructed and engineered thirteen ancestral sequences of the stator B-subunit to evaluate the functional properties and ionic power source of the stator proteins at reconstruction nodes to evaluate the potential of ancestral sequence reconstruction (ASR) methods for stator engineering and to test specific motifs previously hypothesized to be involved in ion-selectivity. We found that all thirteen of our reconstructed ancient B-subunit proteins could assemble into functional stator complexes in combination with the contemporary Escherichia coli MotA-subunit to restore motility in stator deleted E. coli strains. The flagellar rotation of the thirteen ancestral MotBs was found to be Na + independent which suggested that the F30/Y30 residue was not significantly correlated with sodium roton phenotype, in contrast to what we had reported previously. Additionally, four among the thirteen reconstructed B-subunits were compatible with the A-subunit of Aquifex aeolicus and able to function in a sodium-independent manner. Overall, this work demonstrates the use of ancestral reconstruction to generate novel stators and quantify which residues are correlated with which ionic power source.
Location: Saudi Arabia
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for SRIKANTH PEDIREDDY.