ABSTRACT
Abstract Streptococcus pneumoniae is one of the most frequent opportunistic pathogens worldwide. DNA processing protein A (DprA) is an important factor involved in bacterial uptake and DNA integration into bacterial genome, but its role in S. pneumoniae virulence remains unclear. The aim of this study was to characterize the effects of the pneumococcal dprA gene on the pathogenesis of S. pneumoniae. To construct a dprA-deficient pneumococcal strain, the dprA gene of the S. pneumoniae strain D39 was inactivated. The virulence of this dprA-deficient strain, designated ΔD39, was compared with that of the wild-type strain by evaluating their respective capabilities to adhere to human pulmonary epithelial cells (PEC-A549) and by analyzing their choline-binding protein expression levels. In addition, the expression profiles of genes associated with virulence and host survival assays were also conducted with the mutant and the wild-type strain. Our results indicate that the capability of ΔD39 to adhere to the PEC-A549 airway cells was significantly lower (p < 0.01) compared with D39. Additionally, the 100-KD choline-binding protein was not detected in ΔD39. The addition of competence-stimulating peptide (CSP) lead to a significantly reduction of psaA mRNA expression in the dprA-deficient mutant and an increased level of psaA transcripts in the wild-type strain (p < 0.01). The median survival time of mice intraperitoneally infected with ΔD39 was significantly higher (p < 0.01) than that of mice infected with D39. The results of this study suggest that DprA has a significant effect on virulence characteristics of S. pneumoniae by influencing the expression of choline-binding protein and PsaA.
Subject(s)
Humans , Animals , Pneumococcal Infections/pathology , Streptococcus pneumoniae/pathogenicity , Bacterial Proteins/metabolism , Bacterial Adhesion , Virulence Factors/analysis , Membrane Proteins/metabolism , Pneumococcal Infections/microbiology , Streptococcus pneumoniae/genetics , Bacterial Proteins/analysis , Bacterial Proteins/genetics , Survival Analysis , Cell Line , Virulence Factors/genetics , Disease Models, Animal , Epithelial Cells/microbiology , Gene Knockout Techniques , Membrane Proteins/genetics , MiceABSTRACT
<p><b>OBJECTIVE</b>To investigate the changes of hipbone biomechanics after the resection of ischiopubic tumors and their relationships with the complications in the convalescent stage, and directing the postoperative pelvic reconstruction.</p><p><b>METHODS</b>DICOM data were used to create an intact hipbone finite element model and postoperative model. The biomechanical indices on the same region in the two models under the same boundary condition were compared. The differences of displacement, stress, and strain of the two models were analyzed with statistical methods.</p><p><b>RESULTS</b>The distribution areas of the hipbone nodes' displacement, stress, and strain were similar before and after the simulated operation. The sacroiliac joint nodes' displacement (P=0.040) and strain (P=0.000), and the acetabular roof nodes' stress (P=0.000) and strain (P=0.005) of two models had significant differences, respectively.But the sacroiliac joint nodes' stress (P=0.076) and the greater sciatic notch nodes' stress (P=0.825) and strain (P=0.506) did not have significant differences.</p><p><b>CONCLUSIONS</b>The resection of ischiopubic tumors mainly affect the biomechanical states of the homolateral sacroiliac joint and acetabular roof. The complications in the convalescent stage are due to the biomechanical changes of the sacroiliac joint and the acetabular roof and disappearances of the stabilization and connection functions of the pubic symphysis and superior ramus of pubis.</p>