Ginkgo biloba L. exocarp petroleum ether extract inhibits methicillin-resistant Staphylococcus aureus by modulating ion transport, virulence, and biofilm formation in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: As reported in the Ancient Chinese Medicinal Books, Ginkgo biloba L. fruit has been used as a traditional Chinese medicine for the treatment asthma and cough or as a disinfectant. Our previous study demonstrated that G. biloba exocarp extract (GBEE), an extract of a traditional Chinese herb, inhibits the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilms. However, GBEE is a crude extract that contains many components, and the underlying mechanisms of purified GBEE fractions extracted with solvents of different polarities are unknown. AIM OF THE STUDY: This study aimed to investigate the different components in GBEE fractions extracted with solvents of different polarities and their antibacterial effects and mechanisms against MRSA and Staphylococcus haemolyticus biofilms both in vitro and in vivo. METHODS: The components in different fractions were detected by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). Microbroth dilution assays and time growth curves were used to determine the antibacterial effects of the fractions on 15 clinical bacterial isolates. Crystal violet staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to identify the fractions that affected bacterial biofilm formation. The potential MRSA targets of the GBEE fraction obtained with petroleum ether (PE), denoted GBEE-PE, were screened by transcriptome sequencing, and the gene expression profile was verified by quantitative polymerase chain reaction (qPCR). RESULTS: HPLC-HRMS analysis revealed that the four GBEE fractions (extracted with petroleum ether, ethyl acetate, n-butanol, and water) contained different ginkgo components, and the antibacterial effects decreased as the polarity of the extraction solvent increased. The antibacterial activity of GBEE-PE was greater than that of the GBEE fraction extracted with ethyl acetate (EA). GBEE-PE improved H. illucens survival and reduced MRSA colonization in model mouse organs. Crystal violet staining and SEM and TEM analyses revealed that GBEE-PE inhibited MRSA and S. haemolyticus biofilm formation. Transcriptional analysis revealed that GBEE-PE inhibits MRSA biofilms by altering ion transport, cell wall metabolism and virulence-related gene expression. In addition, the LO2 cell viability and H. illucens toxicity assay data showed that GBEE-PE at 20 mg/kg was nontoxic. CONCLUSION: The GBEE fractions contained different components, and their antibacterial effects decreased with increases in the polarity of the extraction solvent. GBEE-PE limited MRSA growth and biofilm formation by affecting ion transport, cell wall synthesis, and virulence-related pathways. This research provides a more detailed overview of the mechanism by which GBEE-PE inhibits MRSA both in vitro and in vivo and suggests that GBEE-PE is a new prospective antimicrobial with the potential to be used in MRSA therapeutics in the future.

Comparison of Clinical Effects of the Modified Masquelet Technique and Kirschner Wire External Fixation-Assisted Autogenous Bone Transplantation in the Treatment of Segmental Metacarpophalangeal Bone Defects.

OBJECTIVE: The present study aims to explore the (1) clinical effects of the modified Masquelet technique, whose improved Masquelet technique innovates the in vitro plasticity of the bone cement module and prefabricated hollow design, and the Kirschner wire external fixation-assisted autologous bone transplantation technique in the treatment of segmental metacarpophalangeal bone defects and (2) the differences between the two techniques. METHODS: The clinical data of 32 patients with segmental metacarpophalangeal bone defects (15 patients treated with the modified Masquelet technique and 17 patients treated with the self-made Kirschner wire external fixation technique) admitted to our department between January 2012 and January 2020 were retrospectively analyzed. The postoperative bone healing time, hand function, and complications were compared between the two groups. RESULTS: The two groups were comparable; there were no significant differences in age, sex, length of bone defect, and time from injury to operation between the two groups (P > 0.05). All patients were followed up with for 6-24 months (average = 13.7 months), and all patients with segmental metacarpophalangeal bone defects achieved fracture healing. The postoperative hospital stay, fracture healing time, functionary scores of the affected limb, and incidence of severe complications were better in the modified group than in the external fixation group (P < 0.05). CONCLUSION: Compared with the Kirschner wire external fixation stent assisted autologous bone transplantation, the improved Masquelet technique has the advantages of simple operation, fast healing, accurate effect, wide indications, and less complications, making it more worthy of clinical promotion.

Temperature-Dependent Tunneling in Furan Oligomer Single-Molecule Junctions.

Two commonly observed charge transport mechanisms in single-molecule junctions are coherent tunneling and incoherent hopping. It has been generally believed that tunneling processes yield temperature-independent conductance behavior and hopping processes exhibit increasing conductance with increasing temperature. However, it has recently been proposed that tunneling can also yield temperature-dependent transport due to the thermal broadening of the Fermi energy of the contacts. In this work, we examine a series of rigid, planar furan oligomers that are free from a rotational internal degree of freedom to examine the temperature dependence of tunneling transport directly over a wide temperature range (78-300 K). Our results demonstrate conductance transition from a temperature-independent regime to a temperature-dependent regime. By examining various hopping and tunneling models and the correlation between the temperature dependence of conductance and molecular orbital energy offset from the Fermi level, we conclude thermally assisted tunneling is the dominant cause for the onset of temperature-dependent conductance in these systems.

Microscopic anatomy and ultrastructure of the resin ducts of Ferula ferulaeoides (Steud.) Korov. in Xinjiang.

Ferula ferulaeoides (Steud.) Korov. is a perennial herb that belongs to Umbelliferae (Apiaceae). Its resin and roots have extensive commercial and medicinal value in the Xinjiang region. However, the resin-secreting resin ducts (RDs) of F. ferulaeoides have not been studied in detail. This study used optical and transmission electron microscopy to explore the anatomical features, including the distribution, size, and structure, of the RDs among different organs of F. ferulaeoides. The microstructure data revealed that the RDs consisted of a round lumen, a layer of secretory cells, and multiple layers of sheath cells. Notably, the RDs in stem were arranged alternatively in a multilayered ring with vascular bundles of three distinct sizes. The ultrastructural analysis revealed that organelles in the secretory cells potentially play important roles in resin secretion. Those data may be of great significance to understanding the anatomy of the RDs in Ferula L. and Umbelliferae.

Measuring the expression and activity of the CAT enzyme to determine Al resistance in soybean.

To elucidate the mechanism of soybean resistance to Al, physiological and biochemical indices and antioxidant enzyme expression and activities were systematically analyzed in Al-sensitive (Glycine max Merr., Yunnan Province of China, SB) and Al-resistant Dambo (Glycine max Merr., Kyoto of Japan, RB) black soybean plants. According to the results, the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in RB root tips were significantly lower than those in SB root tips, though the opposite results occurred for soluble protein contents. Moreover, the expression and activities of superoxide dismutase (SOD, EC1.15.1.1.1.1.1.1), peroxidase (POD, EC1.11.1.7) and catalase (CAT, EC1.11.1.6) under 0-400 µM Al for 0-96 h were greater in RB than in SB. However, below 100 µM Al, the activities of those enzymes in SB increased with increasing Al concentration and treatment duration, with SOD activity being lowest and CAT activity exceeding that of POD with increasing Al concentration. Overall, enzyme activity in SB treated with Al at concentrations greater than 200 µM was lower than that in the SB control (CK; not treated with Al) and decreased with treatment duration. Additionally, at Al concentrations lower than 200 µM, enzyme activities in RB were significantly greater than those in RB CK and increased with both Al concentration and treatment duration. Moreover, enzyme activity in RB treated with 400 µM Al was slightly greater than that in RB CK. Thus, CAT activity determines soybean resistance to Al. These results indicate that soybean resistance to Al can be enhanced by regulating the expression and activity of antioxidant enzymes to remove H2O2 under Al stress.

Syntheses, structural characterisation and electronic structures of ferrocenyl-osmafuran heterobinuclear organometallic complexes.

The heterobinuclear complex OsCl2(PPh3)2[CHC(PPh3)CFcO] (Fc = (C5H4)Fe(C5H5)) (1) in which the two metal centers were connected by the skeleton of the osmafuran and cyclopentadienyl was synthesized via a one-pot reaction of OsCl2(PPh3)3 and FcCOC[triple bond, length as m-dash]CH in high yield. Three derivatives (Os(η2-OCOO)(PPh3)2[CHC(PPh3)CFcO] (2), Os(NCS)2(PPh3)2[CHC(PPh3)CFcO] (3), and OsCl2(dppb)[CHC(PPh3)CFcO] (dppb = Ph2P(CH2)4PPh2) (4)) were obtained by the ligand substitution reactions of complex 1 with different reagents (Cs2CO3 (2), NaSCN (3) and dppb (4)), respectively. All of these complexes were characterized by NMR spectroscopy and elemental analysis and the structures of complexes 1, 3 and 4 were further confirmed by single crystal X-ray diffraction. Their electrochemical properties were studied by cyclic voltammetry and square wave voltammetry. The first redox wave was ascribed to the couple Os(ii)/Os(iii). All of these complexes exhibit two redox processes with a large peak separation. However, UV-Vis-NIR combined with theoretical calculation clearly indicated that (1) the Os center plays a major role in the one-electron oxidation process of heterobinuclear complexes 1-4 and the osmafuran could be better described as a carbene ligand; (2) the electronic communication between the Os and Fe center is absent, and the osmafuran with the electron-withdrawing phosphonium substituent actually functioned as an insulating bridge.

[Fabrication and analysis of red-green resonant complementary optically variable sub-wavelength microstructures].

Principles of design and production of dual-layer sub-wavelength grating microstructures are analyzed thoroughly. Novel methods for designing and fabricating such structures, with the characteristics of using rectangular grating index profiles when designed and using holographic interference lithography and coating processes when produced, are proposed. Microstructures fabricated by use of this method, will have the same resonant and optically variable properties with pre-designed structures, even improving its color qualities of lights reflected. A sub-wavelength security microstructure with the unique performances of red-green resonant complementary optically variability in color was designed and manufactured successfully and its resonant optically variable spectrum and color changing characteristics were verified theoretically and experimentally. Study results indicate that sinusoidal grating microstructures manufactured have the same resonant and optically variable characteristics, such as the resonant spectrum, color, spectral peak and peak splits, etc. with the pre-designed structures. A rectangular index profile grating is not the necessary requirement to produce resonance behaviors and the grating regions can have any profile such as the holographic type as long as its diffraction characteristics and equivalent waveguide representation are the same with the designed rectangular grating microstructures. The methods proposed are feasible in practice, lowering the making complexity and with potential of low-cost mass production commercially by use of the current holographic manufacture equipments.

[Inhibition of sulfite oxidation catalyzed by heavy metals in dual alkali flue gas desulfurization slurry].

Heavy metals accumulated in slurry of dual alkali flue gas desulfurization (FGD) present a significant catalysis to SO3(2-) oxidation, resulting in a waste of effective components for desulfurization. Na2S was adopted to precipitate heavy metal ions in FGD slurry, and the oxidation rate of SO3(2-) was obtained under different concentrations of heavy metal ions, to reveal the inhibition effect of Na2S on SO3(2-) oxidation catalyzed by heavy metal ions. Mn2+ showed a remarkable catalysis to SO3(-2) oxidation, as the initial oxidation rate of SO3(2-) was tripled to 0.65 mmol/(L x min) by adding 1.0 mmol/L Mn2+ into the slurry. SO3(2-) was catalytically oxidized rapidly with the reaction order 0.169 of Mn2+ within first 60 minutes, so it is of great importance to control the concentration of Mn2+ to inhibit SO3(2-) oxidation. At initial pH value of 6.50-8.50, Na2S removed heavy metal ions effectively from FGD slurry. Higher pH value favored the removal of heavy metal ions. The removal efficiencies of Mn2+, Zn2+, Ni2+ and Cd2+ were 91.0%, 88.1%, 85.5%, and above 99.9% respectively under the conditions of initial pH value 8.50 and Na2S dosage 240.0 mg/L. Mn2+ could be used as an indicator for the concentration of the heavy metal ions in the slurry. As the Mn2+ concentration decreased from 1.0 mmol/L to 5.0 x 10(-3) mmol/L by adding Na2S, the initial oxidation rate of SO3(2-) decreased by 64.6% to 0.23 mmol/(L x min). The desulfurization efficiencies increase 3.8%-5.1% by adding Na2S in a pilot scale setup. It comes to conclusion that heavy metal ions precipitation by adding Na2S with an indicator of Mn2+ to inhibit catalytic oxidation of SO3(2-) is feasible to reduce the consumption of desulfurizer in FGD slurry.

N-(Acetamido)thiourea based simple neutral hydrogen-bonding receptors for anions.

N-(Acetamido)-N'-phenylthioureas (4-6) were found to be efficient anion receptors with higher anion affinity than their N-benzamido-N'-phenylthiourea counterparts (1 and 2). The N'-phenylthiourea moiety in 4-6 was shown to be the chromophore with an absorption maximum at ca. 270 nm. It was found that, in the presence of anions, the absorption at ca. 270 nm of 4-6 (except 5f) in acetonitrile (MeCN) was blue shifted and enhanced while a red-shifted shoulder appeared at ca. 295 nm, together with an isosbestic point at ca. 240 nm. The 1:1 anion binding constants of 4-6, for example at 10(6)-10(7) M(-1) order of magnitude for AcO(-) in MeCN, were found to be higher than those of 1 and 2, although the acidity of the thioureido -NH protons in 4-6 is lower than that in 1 and 2. (1)H NMR data indicates that the N-N single bond in 4-6 is twisted but less than that in 1 and 2. A conformation change at the N-N single bond of 4-6 was suggested to occur upon anion binding which leads to a planar hydrogen-bonding network in the anion binding complex in which a charge transfer takes place with the N-acyl moiety being the electron acceptor. Variations in the CD signals of a proline derivative 6 bearing a chiral center in the N-amido moiety provide direct evidence for this conformation change upon its binding with anions in MeCN. The amplified effect of substituent X at the N'-phenyl ring of 5 on the anion binding constant supports the conclusion of anion-binding switched charge transfer in the anion binding complex. (1)H NMR and absorption titrations for 5 indicated that the anion-receptor interaction was of a hydrogen-bonding nature until the N'-phenyl substituent X is as electron-withdrawing as m-CF(3) (5e). With X being the more electron-withdrawing p-NO(2) (5f), deprotonation of the thioureido -NH occurs in the presence of anion. Results reported here confirm that N-amidothioureas derived from both N-aliphatic and N-aromatic amides can in general be a family of efficient hydrogen-bonding receptors, with the aliphatic N-amido derivatives being more efficient. This provides a wider structural diversity for designing thiourea-based functional molecules such as anion receptors and organocatalysts. Preliminary experiments confirm that 6 could catalyse efficiently the reduction of nitrostyrene in CH(2)Cl(2) and MeCN.

Anion binding in aqueous solutions by N-(Isonicotinamido)-N'-phenylthiourea-based simple synthetic neutral receptors. role of the hydrophobic microenvironment of the receptor molecule.

N-(Isonicotinamido)-N'-(substituted-phenyl)thioureas (1a-e, substituent X = p-OCH3, p-CH3, H, m-Br, and m-CF3) have been designed as neutral receptors, in order to prove the influence of conformational issues on the ability to bind anions in aqueous solutions. Compounds 1a-e were shown to create a hydrophobic microenvironment around the thiourea group, favoring hydrogen bonding interactions, by evidence from quantum mechanic calculations, thermodynamic analysis, NMR aromatic current shielding, and comparative anion binding. Referring to N-(substituted-benzamido)thioureas (2a-e, substituent Y = H, m-Cl, m-NO2, m,m-Cl,Cl, and p-NO2), we showed that, for the hydrophobic microenvironment to be operative in aqueous solutions, the amido -NH proton needs to be acidic enough.

Intramolecular hydrogen bonding and anion binding of N-benzamido-N'-benzoylthioureas.

N-(p-Dimethylamino)benzoyl-N'-phenylthiourea as an N-acylthiourea is known to be unable to bind anions due to a strong intramolecular hydrogen bond (IHB). We show here that by inserting an amido group in the N'-phenyl side the newly designed N-benzamido-N'-benzoylthioureas, despite this IHB too, bind strongly to anions with binding constants on the order of 10(6)-10(7) mol(-1) L. Results suggest that potential anion receptors or organocatalysts could be developed on the basis of this framework with a wide structural diversity.

N-amidothiourea based PET chemosensors for anions.

Neutral N-amidothiourea based PET anion sensors bearing a pyrene fluorophore, 1-3, were synthesized and their fluorescent response toward anions was assessed. The anion quenching and binding constants were found to be much higher than those of the corresponding PET sensors bearing a simple thiourea receptor despite a higher oxidation potential of the electron donor and a relatively longer spacer (CH(2))(3) between the signal reporter and binding receptor in 1-3. This was explained in terms of a much more substantial increase in the electron donating ability of amidothiourea upon anion binding.

In vitro and in vivo activities of HQQ-3, a new triazole antifungal agent.

The activity of HQQ-3, a new triazole antifungal agent, was evaluated and compared with those of fluconazole, ketoconazole and terbinafine in vitro and with fluconazole in vivo. HQQ-3 exhibited potent in vitro activity against clinically important fungi. The activity of HQQ-3 against Candida spp. was superior to those of fluconazole and terbinafine and comparable or superior to that of ketoconazole. HQQ-3 retained potent activity against Candida albicans strains with low levels of susceptibility to fluconazole (fluconazole MIC80s range, 4 to >64 microg/ml). Against Cryptococcus neoformans and filamentous fungi, the activity of HQQ-3 was superior to that of fluconazole. HQQ-3 also exhibited potent in vivo activity against murine systemic infections caused by C. albicns and C. krusei. The 50% effective doses against these infections were 0.12 to 1.9 mg/kg of body weight. These result suggest that HQQ-3 may be useful in the treatment of candidiasis.

Development of N-benzamidothioureas as a new generation of thiourea-based receptors for anion recognition and sensing.

A series of neutral N-(substituted-benzamido)-N'-phenylthioureas (substituent = p-OC(2)H(5), p-CH(3), m-CH(3), H, p-Cl, p-Br, m-Cl, and p-NO(2)) were designed as anion receptors, in which the thiourea binding site was attached to the benzamido moiety via an N-N bond. The absorption spectra of these N-benzamidothioureas in acetonitrile peaked at ca. 270 nm were found to show unprecedented red shifts by 7 373 to 14 325 cm(-1) in the presence of anions such as AcO(-), F(-), and H(2)PO(4)(-). Under the same conditions, the classic neutral thiourea receptors, N-(substituted-phenyl)-N'-phenylthioureas, showed absorption spectral shifts in most cases of less than 800 cm(-1) with one exception of 6501 cm(-1). Control experiments, effects of protic solvent, and (1)H NMR titration confirmed the formation of hydrogen-bonding complexes between the new N-benzamidothiourea receptors and anions. The binding constants with AcO(-), for example, are at 10(5)-10(7) mol(-1) L order of magnitude, which are 13 to 590 times those of the corresponding classic N-phenylthioureas in the same solvent. It was found that, whereas the absorption of the N-benzamidothiourea receptors showed essentially no dependence on the substituent, the substantially red-shifted new absorption band of the N-benzamidothiourea-anion binding complex was sensitively subject to the substituent. A linear relationship was found between the absorption energies of the N-benzamidothiourea-acetate binding complexes and the Hammett constants of the substituents with a negative slope of -0.34 eV. This led to the assignment that the substantially red-shifted absorption band was the ground-state intramolecular charge-transfer absorption with the substituent locating in the electron acceptor moiety. It was concluded that anion binding to the thiourea moiety of the N-benzamidothiourea receptors switched on their ground-state charge transfer. An anion-binding induced structural change was suggested to occur around the N-N bond in N-benzamidothioureas, which resulted in a substantially increased electron donating ability of the electron donor in the receptor molecules. As a consequence, the ground-state charge transfer takes place in the N-benzamidothiourea-anion binding complexes, leading to unprecedented red shifts in the absorption spectra and substantially enhanced anion binding affinities than those of the corresponding N-phenylthiourea receptors. N-Benzamido-N'-phenylthioureas represent a new generation of neutral thiourea-based anion receptors that show substantially improved anion binding performance important for anion sensing and recognition.

[The test of metal-ceramic bonding strength among three ceramic alloies].

PURPOSE: To compare the metal-ceramic bonding strength of different ceramic alloies. METHODS: 30 wax sheets were divided into 6 groups at random. Each group included 5 sheets. After being invested conventionally with Bellaves SH,the samples were casted and fused with porcelain.The metal-ceramic bonding strength was evaluated. RESULTS: The highest bonding strength was found in Bio Herador N alloy, and then in TILITE alloy and Heraenium S alloy respectively. Bio Herador N alloy and TILITE alloy all had significant differences of the bonding strength before and after treatment (P<0.05). There was no significant differences in the bonding strength of the Heraenium S alloy after treatment (P>0.05). CONCLUSION: The bonding strength of precious metal-ceramic was higher than that of non-precious metal-ceramic.Pre-oxygen treatment can improve the metal-ceramic bonding strength of Bio Herador N alloy and TILITE alloy,but it had no effect on the metal-ceramic bonding strength of the Heraenium S alloy.