755 research outputs found
SCI citation analysis and impact factor prediction of JZUS-A in 2008
No full textWe analysis the SCI citation of Journal of Zhejiang University-SCIENCE A, predict its 2008 Impact Factor in the range of 0.222~0.274, and list the most highly cited articles
WQ-3810 exerts high inhibitory effect on quinolone-resistant DNA gyrase of Salmonella Typhimurium
No full textThe inhibitory effect of WQ-3810 on DNA gyrase was assayed to evaluate the potential of WQ-3810 as a candidate drug for the treatment of quinolone resistant Salmonella Typhymurium infection. The inhibitory effect of WQ-3810, ciprofloxacin and nalidixic acid was compared by accessing the drug concentration that halves the enzyme activity (IC50) of purified S. Typhimurium wildtype and mutant DNA gyrase with amino acid substitution at position 83 or/and 87 in subunit A (GyrA) causing quinolone resistance. As a result, WQ-3810 reduced the enzyme activity of both wildtype and mutant DNA gyrase at a lower concentration than ciprofloxacin and nalidixic acid. Remarkably, WQ-3810 showed a higher inhibitory effect on DNA gyrase with amino acid substitutions at position 87 than with that at position 83 in GyrA. This study revealed that WQ-3810 could be an effective therapeutic agent, especially against quinolone resistant Salmonella enterica having amino acid substitution at position 87. (Up to 150 words
WQ-3810: A new fluoroquinolone with a high potential against fluoroquinolone-resistant Mycobacterium tuberculosis
No full textFluoroquinolone (FQ) resistance in Mycobacterium tuberculosis (Mtb), caused by amino acid substitutions in DNA gyrase, has been increasingly reported worldwide. WQ-3810 is a newly developed FQ that is highly active against FQ-resistant pathogens; however, its activity against Mtb has not been evaluated. Herein we examined the efficacy of WQ-3810 against Mtb through the use of recombinant Mtb DNA gyrases. In addition, in vitro anti-mycobacterial activity of WQ-3810 was evaluated against recombinant Mtb var. bovis Bacille Calmette-Guerin strains in which gyrase-coding genes were replaced with Mtb variants containing resistance-conferring mutations. WQ-3810 showed a higher inhibitory activity than levofloxacin against most recombinant DNA gyrases with FQ-resistance mutations. Furthermore, WQ-3810 showed inhibition even against a DNA gyrase variant harboring a G88C mutation which is thought to confer the highest resistance against FQs in clinical Mtb isolates. In contrast, the FQ susceptibility test showed that WQ-3810 had relatively weak mycobactericidal activity compared with moxifloxacin. However, the combination of WQ-3810 and ethambutol showed the greatest degree of synergistic activity against recombinant strains. Since FQs and ethambutol have been used in multi-drug therapy for tuberculosis, WQ-3810 might represent a new, potent anti-tuberculosis drug that can be effective even against FQ-resistant Mtb strains
WQ-3810 inhibits DNA gyrase activity in ofloxacin-resistant Mycobacterium leprae
No full textBackground: Mycobacterium leprae causes leprosy and ofloxacin is used to control this bacterium. However, specific amino acid substitutions in DNA gyrases of M. leprae interferes with the effect of ofloxacin. Methodology/principal findings: Here we tested the inhibitory effect of WQ-3810 on DNA gyrases in M. leprae, using recombinant gyrases. We theorized that WQ-3810 and DNA gyrases interacted, which was tested in silico. Compared with control drugs like ofloxacin, WQ-3810 showed a better inhibitory effect on ofloxacin-resistant DNA gyrases. The in-silico study showed that, unlike control drugs, a specific linkage between a R1 group in WQ-3810 and aspartic acid at position 464 in the subunit B of DNA gyrases existed, which would enhance the inhibitory effect of WQ-3810. This linkage was confirmed in a further experiment, using recombinant DNA gyrases with amino acid substitutions in subunits B instead. Conclusions/significance: The inhibitory effect of WQ-3810 was likely enhanced by the specific linkage between a R1 group residue in its structure and DNA gyrases. Using interactions like the one found in the present work may help design new fluoroquinolones that contribute to halt the emergence of antibiotic-resistant pathogens. (c) 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved
Possible REE constraints on the depositional and diagenetic environment of Doushantuo Formation phosphorites containing the earliest metazoan fauna
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Pb-Pb ages of Neoproterozoic Doushantuo phosphorites in South China: constraints on early metazoan evolution and glaciation events
No full textEffectiveness of Fluoroquinolones with Difluoropyridine Derivatives as R1 Groups on the Salmonella DNA Gyrase in the Presence and Absence of Plasmid-Encoded Quinolone Resistance Protein QnrB19
No full textAims: WQ-3810 has strong inhibitory activity against Salmonella and other fluoroquinolone-resistant pathogens. The unique potentiality of this is attributed to 6-amino-3,5-difluoropyridine-2-yl at R1 group. The aim of this study was to examine WQ-3810 and its derivatives WQ-3334 and WQ-4065 as the new drug candidate for wild-type Salmonella and that carrying QnrB19. Materials and Methods: The half maximal inhibitory concentrations (IC(50)s) of WQ-3810, WQ-3334 (Br atom in place of methyl group at R8), and WQ-4065 (6-ethylamino-3,5-difluoropyridine-2-yl in place of 6-amino-3,5-difluoropyridine-2-yl group at R1) in the presence or absence of QnrB19 were assessed by in vitro DNA supercoiling assay utilizing recombinant DNA gyrase and QnrB19. Results: IC(50)s of WQ-3810, WQ-3334, and WQ-4065 against Salmonella DNA gyrase were 0.031 +/- 0.003, 0.068 +/- 0.016, and 0.72 +/- 0.39 mu g/mL, respectively, while QnrB19 increased IC(50)s of WQ-3810, WQ-3334, and WQ-4065 to 0.44 +/- 0.05, 0.92 +/- 0.34, and 9.16 +/- 2.21 mu g/mL, respectively. Conclusion: WQ-3810 and WQ-3334 showed stronger inhibitory activity against Salmonella Typhimurium DNA gyrases than WQ-4065 even in the presence of QnrB19. The results suggest that 6-amino-3,5-difluoropyridine-2-yl group at R1 is playing an important role and WQ-3810 and WQ-3334 to be good candidates for Salmonella carrying QnrB19
Salam hypothesis and the role of phase transition in amino acids
No full textSalam hypothesis was elaborated in the First Trieste Conference on Chemical Evolution. We spent twelve years on a number of experiments (i.e. temperature-dependence of X-ray diffraction, neutron diffraction, atomic force microscopy of the surface structure, specific heat measurement, DC and AC magnetic susceptibilities, longitudinal ultrasonic attenuation and velocity, H-1 CRAMPS and C-13 CP/MAS solid state NMR studies, Raman spectra & natural optical rotation) to verify the second-order phase transition and the role in amino acids. The configuration transformation from D- to L-type was refuted by gas chromatographic analysis of Chirasil-Val capillary column of DL, D- and L-valine. This paper focuses attention on the role of phase transition in amino acid, which might play a bifurcation-type mechanism in a chirally-pure state instead of a direct configuration change from D- to L-amino acid below T-c.BiologyGeosciences, MultidisciplinaryCPCI-S(ISTP)
Interaction of Quinolones Carrying New R1 Group with Mycobacterium leprae DNA Gyrase
No full textBackground: Leprosy is a chronic infectious disease caused by Mycobacterium leprae and the treatment of choice is ofloxacin (OFX). Specific amino acid substitutions in DNA gyrase of M. leprae have been reported leading to resistance against the drug. In our previous study, WQ-3810, a fluoroquinolone with a new R1 group (6-amino-3,5-difluoropyridin-2-yl) was shown to have a strong inhibitory activity on OFX-resistant DNA gyrases of M. leprae, and the structural characteristics of its R1 group was predicted to enhance the inhibitory activity. Methodology/Principal Finding: To further understand the contribution of the R1 group, WQ-3334 with the same R1 group as WQ-3810, WQ-4064, and WQ-4065, but with slightly modified R1 group, were assessed on their activities against recombinant DNA gyrase of M. leprae. An in silico study was conducted to understand the molecular interactions between DNA gyrase and WQ compounds. WQ-3334 and WQ-3810 were shown to have greater inhibitory activity against M. leprae DNA gyrase than others. Furthermore, analysis using quinolone-resistant M. leprae DNA gyrases showed that WQ-3334 had greater inhibitory activity than WQ-3810. The R8 group was shown to be a factor for the linkage of the R1 groups with GyrB by an in silico study. Conclusions/Significance: The inhibitory effect of WQ compounds that have a new R1 group against M. leprae DNA gyrase can be enhanced by improving the binding affinity with different R8 group molecules. The information obtained by this work could be applied to design new fluoroquinolones effective for quinolone-resistant M. leprae and other bacterial pathogens
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