Objective:To investigate the predictive value of Pitt bacteremia score (PBS) on 28-day mortality of patients with extensively drug-resistant Klebsiella pneumoniae (XDR-KP) bloodstream infection.Methods:A retrospective cohort study was conducted to analyze the clinical characteristics of patients with XDR-KP bloodstream infection admitted to the Emergency Intensive Care Unit of Nanjing Drum Tower Hospital from January, 2018, to December, 2021. The patients were divided into the survival and non-survival groups according to the 28-day survival. Multivariate logistic regression analysis was performed to determine the risk factors of 28-day mortality of the patients. Receiver operating curve (ROC) curve was drawn to analyze the predictive value of PBS in 28-day mortality of patients with XDR-KP bloodstream infection. The correlations between PBS, and acute physiology and chronic health evaluation II (APACHE II) and sequential organ failure (SOFA) assessment were performed using Pearson correlation coefficient. The optimal cut-off value of PBS score was used as the boundary point to group the differences between APACHE II and SOFA scores in different groups. Kaplan-Meier method was used to analyze the prognosis of patients with XDR-KP bloodstream infection.Results:A total of 118 patients (82 males and 36 females) with XDR-KP bloodstream infection, aged (65.98±15.16) years, were included in this study. The 28-day mortality was 61.02%. The PBS was significant higher in the non-survival group than in the survival group [(5.68±1.86) vs. (2.48±1.02), P=0.011]. Multivariate logistic regression analysis showed that PBS ( OR=4.940, 95% CI: 2.720-8.968, P=0.008), APACHE II score ( OR=1.630, 95% CI: 1.361-1.952, P=0.010) and SOFA score ( OR=1.879, 95% CI: 1.451-2.422, P=0.009) were independently risk factors of 28-day mortality of patients with XDR-KP bloodstream infection. The area under the ROC curve of the PBS predicting 28-day mortality was 0.970 (95% CI: 0.945-0.995, P<0.001), and the optimal cut-of value was 3.5. In addition, PBS was significantly associated with APACHE II score ( r=0.916, P<0.001) and SOFA score ( r=0.829, P<0.001). Moreover, Kaplan-Meier analysis showed that the 28-day survival rate of patients with PBS <3.5 was significantly higher than that of patients with PBS >3.5 ( P=0.001). Conclusions:PBS is a significant, independent predictor of 28-day mortality in patients with XDR-KP bloodstream infection.

Objective To investigate the effect of fluoride exposure on expression of miRNA (miR)-200c and its target in human osteoblast Saos-2 cells.Methods Saos-2 cells were cultured in DMEM/F-12 medium and treated with fluoride (sodium fluoride,NaF).There were two groups including:control group (0 mg/L) and fluoride group (4 mg/L).Cells were harvested after 48 hours of culture with fluoride.The expression of miR-200c,the mRNA of alkaline phosphatase (ALP),osteocalcin (BGP),the target phosphatase and tensin homolog deleted on chromosome ten (PTEN) and dual-specific phosphatase 1 (DUSP1) of miR-200c was detected by qRT-PCR.The protein expression of PTEN and DUSP1 was detected by Western blotting.Results The expressions of ALP,BGP mRNA and miR-200c in Saos-2 cells in the fluoride group (23.60 ± 1.87,9.41 ± 0.94,8.61 ± 0.26) were higher than those in the control group (1.00 ± 0.11,1.00 ± 0.07,1.00 ± 0.12).The differences were statistically significant (t =-24.084,-18.388,-8.687,P ＜ 0.05).The mRNA expressions of PTEN and DUSP1 in the fluoride group (0.63 ± 0.02,0.38 ± 0.02) were lower than those in the control group (1.02 ± 0.24,1.02 ± 0.24).The differences were statistically significant (t =3.327,5.454,P ＜ 0.05).The protein expressions of PTEN and DUSP1 in Saos-2 cells in the fluoride group (1.19 ± 0.10,0.83 ± 0.07) were lower than those in the control group (1.81 ± 0.14,1.44 ± 0.25).The differences were statistically significant (t =6.250,4.171,P ＜ 0.05).Conclusion Exposure to fluorine may increase the expression of miR-200c in Saos-2 cells,and fluorine may act on PTEN and DUSP1 through miR-200c,downregulates the mRNA and protein expression levels of PTEN and DUSP1.

Objective To study the effect of T-2 toxin on proliferation and cell cycle of rat chondrocytes,in order to provide a new idea in molecular mechanism of T-2 toxin-induced chondrocyte damage.Methods Primary chondrocytes of neonatal Wistar rats were isolated and stained by toluidine blue staining and type Ⅱ collagen immunofluorescence staining.The effects of different concentrations of T-2 toxin [0 (control),1,5,10,20,50,100 μg/L)] on proliferation of chondrocytes for 24 h were detected by cell counting kit-8 (CCK-8) method,and control,1 (low dose),5 (medium dose),and 10 μg/L (high dose) T-2 toxin were selected for subsequent experiment;cell cycle changes were detected by flow cytometry;Real-time PCR and Western blotting were used to detect the effects of T-2 toxin on mRNA and protein expressions of proliferating cell nuclear antigen (PCNA) and Cyclin D1 in chondrocytes.Results With increase of T-2 toxin concentration (control,1,5,10,20,50,100 μg/L),the cell survival rates [(100.00 ± 0.00)％,(93.12 ± 1.66)％,(77.12 ± 1.11)％,(59.44 ± 4.09)％,(46.64 ± 3.86)％,(38.15 ± 3.37)％,(33.79 ± 0.99)％] were decreased,and the differences were statistically significant (F =139.21,P ＜0.05).The percentages of quiescent phase/pre-DNA synthesis phase (G0/G1 phase) ceils in 1,5,10 μg/L T-2 toxin groups [(22.03 ± 0.42)％,(30.54 ± 2.61)％,(36.01 ± 1.51)％] were significantly higher than that in control group [(13.79 ± 1.65)％,P ＜ 0.05];the percentages of DNA synthesis phase (S phase) cells [(60.27 ± 3.53)％,(53.88 ±4.38)％,(49.55 ± 2.49)％] were significantly lower than that in control group [(76.72 ± 4.24)％,P ＜ 0.05].The differences of mRNA levels of PCNA and Cyclin D1 between groups were statistically significant (F =46.80,17.97,P ＜ 0.05),and 5,10 μg/L T-2 toxin groups (0.77 ± 0.13,0.79 ± 0.08,0.60 ± 0.07,0.56 ± 0.05) were lower than the control group (0.99 ± 0.02,1.01 ± 0.01,P ＜ 0.05).The expressions of PCNA protein in 5,10 μg/L T-2 toxin groups (0.69 ± 0.03,0.49 ± 0.03) were lower than that in control group (0.92 ± 0.05,P ＜ 0.05);the expressions of Cyclin D1 protein in 1,5,10 μg/L T-2 toxin groups (0.80 ± 0.06,0.60 ± 0.07,0.33 ± 0.13) were lower than that in control group (0.95 ± 0.07,P ＜ 0.05).Conclusion T-2 toxin can inhibit the proliferation of chondrocytes,which may be worked through influencing the expression of cell cycle protein,causing cell cycle arrest,thereby inhibiting DNA synthesis.