The inhibitory effect of ozanimod on the growth and biofilm formation of Staphylococcus aureus / 中国热带医学

@#Abstract: Objective　To screening new compounds that can inhibit the growth and biofilm formation of Staphylococcus aureus. Methods　Compounds that can inhibit the growth of Staphylococcus aureus were screened from the FDA approved drug library by 96 well plates. The absorbance value of 600 nm wavelength (OD600) was measured by Microplate Reader to detect the growth of Staphylococcus aureus planktonic cells in the culture supernatant. The minimum inhibitory concentration (MIC) of ozanimod against Staphylococcus aureus clinical isolates were detected by micro broth dilution method. The inhibitory effect of sub-inhibitory concentrations of ozanimod on the biofilm formation of Staphylococcus aureus was detected by crystal violet staining. Results　This study found that ozanimod could significantly inhibit the growth of Staphylococcus aureus SA113 (screening reference strain), and the MIC was 25.00 μmol/L. The MIC of ozanimod against 119 clinical isolates of Staphylococcus aureus [65 isolates of methicillin sensitive (MSSA) and 54 isolates of methicillin resistant (MRSA)] was 12.50 or 25.00 μmol/L. The MIC50 and MIC90 of ozanimod against the 119 Staphylococcus aureus isolates all were 25.00 μmol/L. This study found that 6.25, 12.50, 25.00 μmol/L of ozanimod could significantly inhibit the biofilm formation of 2 MSSA and 2 MRSA. The sub-MIC concentration of ozanimod (12.50 μmol/L) could significantly inhibit the biofilm formation of 14 MSSA and 11 MRSA, but had no inhibitory effect on the growth of planktonic cells of these Staphylococcus aureus isolates. Conclusion　Ozanimod can inhibit the growth of Staphylococcus aureus, including MRSA, and has good antibacterial activity. The sub-MIC concentration of ozanimod could significantly inhibit the biofilm formation of Staphylococcus aureus.

Co-adsorption of CO onto a Ag-modified Pt(111)--restructuring of a Ag UPD layer monitored by EC-STM.

The effect of co-adsorption of CO on an underpotentially deposited (UPD) silver monolayer on a Pt(111) single crystal electrode in 0.05 M sulfuric acid is investigated for the first time by means of electrochemical scanning tunneling microscopy (EC-STM). Pure electrochemical experiments suggest that the co-adsorption of CO onto Pt single crystal electrodes previously modified by a monolayer of Ag, forces Ag atoms of the first UPD monolayer into a second adlayer. The present EC-STM studies reveal the formation of a large-area Ag network after the co-adsorption of CO. The resulting Ag nanostructures formed on wide Pt(111) terraces are approximately 0.5 nm high and 10 nm wide. The desorption of the newly formed second Ag adlayer, the oxidation of CO and the desorption of Ag atoms from the first adlayer are monitored by EC-STM and simultaneously detected in the corresponding CVs in three different oxidation peaks. EC-STM images recorded afterwards show the unchanged Pt surface. The presence of Ag on the surface leads to a downward shift of the onset of oxygen adsorption on the Pt(111) surface.

Significance of CD4+ CD25+ CD127(low) regulatory T cells and notch1 pathway in the pathogenesis of aplastic anemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To quantify the CD4+ CD25+ CD127(low) regulatory T cell (Treg), the expression levels of forkhead/winged helix transcription factor FOXP3 and Notch1 mRNA in aplastic anemia (AA) patients before and after treatment, and explore the significance of Treg in pathogenesis of AA.</p><p><b>METHOD</b>CD4+ CD25+ and CD4+ CD25+ CD127(low) T cells in peripheral blood were examined with FACS in 29 AA patients at active phase, 14 at recovery phase, 11 at unrecovery phase, and 15 normal controls. The levels of FOXP3 mRNA and Notch1 mRNA expression were detected with RT-PCR, and the correlations between Treg, FOXP3 mRNA and Notchl mRNA were analyzed.</p><p><b>RESULTS</b>The percentages of peripheral activated CD4+ CD25+ T cells in AA patients at active phase (4.3 +/- 0.7)% and unrecovery phase (4.2 +/- 0.6)% were significantly higher than those in normal controls (2.4 +/- 0.8)% (P < 0.05). The proportion of these cells in AA patients at recovery phase was reduced to (2.6 +/- 0.7)% (P < 0.05), being no difference from that in control group. The number of CD4+ CD25+ CD127(low) T cells in AA patients at active phase (2.4 +/- 1.2)% and unrecovery phase (2.5 +/- 1.1)% was decreased significantly compared with those in normal controls (7.1 +/- 2.7)% (P < 0.01) and in AA patients at recovery phase (5.3 +/- 1.0)% (P < 0.01), there was no difference between the latter two groups. In active phase AA patients, the levels of FOXP3 mRNA and Notchl mRNA (0.260 +/- 0.011 and 0.018 +/- 0.005, respectively) were lower than that in control group (1.307 +/- 0.011 and 0.308 +/- 0.028, respectively) (P < 0.01 and P < 0.01). After treatment, the levels significantly increased to 1.287 +/- 0.012 and 0.281 +/- 0.013 (P < 0.01 and P < 0.01), but there was no difference with that of normal controls (P > 0.05). CD4+ CD25+ CD2(low) T cells and FOXP3 were positively related with Notchl (P < 0.01) in AA patients.</p><p><b>CONCLUSION</b>The decreased number and suppressive activity of CD4 CD25+ CD127(low) Treg cells in the peripheral blood of AA patients cause over-activation of autoreactive T cells and suppression of haematopoiesis. One of the mechanisms maybe the reduced expression of Notch1 in the target cells.</p>