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To evaluate the molecular mechanism of fluoroquinolones resistance in Mycoplasma hominis (MH) clinical strains isolated from urogenital specimens. 15 MH clinical isolates with different phenotypes of resistance to fluoroquinolones antibiotics were screened for mutations in the quinolone resistance-determining regions (QRDRs) of DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE) in comparison with the reference strain PG21, which is susceptible to fluoroquinolones antibiotics. 15 MH isolates with three kinds of quinolone resistance phenotypes were obtained. Thirteen out of these quinolone-resistant isolates were found to carry nucleotide substitutions in either gyrA or parC. There were no alterations in gyrB and no mutations were found in the isolates with a phenotype of resistance to Ofloxacin (OFX), intermediate resistant to Levofloxacin (LVX) and Sparfloxacin (SFX), and those susceptible to all three tested antibiotics. The molecular mechanism of fluoroquinolone resistance in clinical isolates of MH was reported in this study. The single amino acid mutation in ParC of MH may relate to the resistance to OFX and LVX and the high-level resistance to fluoroquinolones for MH is likely associated with mutations in both DNA gyrase and the ParC subunit of topoisomerase IV.

Objective: To investigate the development and dynamic changes of host immune response in DBA/2 mice infected with Plasmodium yoelii 17XL., Methods: Female DBA/2 mice were infected by intraperitoneal (i. p.) injection of 10(6) P. yoelii 17XL parasitized erythrocytes (PRBC). Levels of IL-12, IFN-gamma, IL-4, IL-10 and P. yoelii 17XL-specific antibody in sera were measured by ELISA. Concentrations of NO in cell supernatants were measured by the Griess reaction. Parasitemia, percentage of mononuclear-macrophages of individual mice were monitored daily, and phagocytosis of mononuclear macrophages was also observed., Results: Primary parasitemia in vein blood was developed on day 3 postinfection, which peaked with a level of 46. 9% on day 9. Most mice cleared the infection and survived by day 20 postinfection. From day 6 to day 16, the phagocytosis of PRBC by rodent macrophages was observed on the blood smear. Infected mice had a continuously increased level of IL-12 in serum from day 1 postinfection. Accordingly, high level of IFN-gamma was also detected in sera from day 1 postinfection, which peaked on day 6. Infected mice produced higher level of IL-4 and IL-10 in serum on day 6 postinfection, which peaked on day 9 and day 15 postinfection respectively. In addition, splenocytes from infected mice produced significantly higher level of NO on day 6 and 20 postinfection. Level of P. yoelii 17XL-specific IgG was determined in the sera of infected mice with a steadily increased trend after infection, which peaked on day 70 postinfection., Conclusions: Effective polarizing of Th1 cells is significant in inhibition of parasitemia and eventual clearance of the Plasmodium parasites. Activated mononuclear-macrophages play a key role in inhibiting parasitemia in the early phase of infection with P. yoelii 17XL.

Objectives: To investigate mechanism for the increasing level of serum vascular endothelial growth factor(VEGF) in tumour patients during radiotherapy and the inhibitory action of the antisense oligodeoxynucleotide (AS-ODN) to the expression of VEGF protein by radiotherapy in the prostate cancer cell line (PC3M)., Methods: To observe the changes of serum VEGF in the prostate cancer patients during radiotherapy dynamically and the inhibitory action of the antisense oligodeoxynucleotide to the expression of VEGF by radiotherapy in PC3M., Results: The changes of serum VEGF in three patients receiving radiotherapy had been observed continuously. The levels of serum VEGF began to increase when the patients received radiotherapy and rised up to peak value after fifteen days, then declined to the range of pre-radiotherapy. Irradiating the PC3M cells with X-rays significantly increased the VEGF expression and secretion. The expression of VEGF protein in the group treated by VEGF AS-ODNs and X-ray irradiation decreased significantly than the group treated only by X-ray irradiation., Conclusions: The induction of VEGF protein expression by X-ray irradiation in tumor cells may result in the increasing of the VEGF in the prostate cancer patients during radiotherapy and the induction can be blocked by VEGF AS-ODNs.