Effects of human ß-defensin-3 on biofilm formation­regulating genes dltB and icaA in Staphylococcus aureus.

An understanding of the regulatory mechanisms that drive Staphylococcus aureus biofilm formation may lead to the development of an effective strategy to control the increasing number of refractory clinical infections it causes. The present study examined the effects of the antimicrobial agent human ß­defensin 3 (hBD­3) and the antibiotics vancomycin and clindamycin on the expression of the S. aureus biofilm formation­regulating genes, icaA and dltB, during bacterial adhesion and biofilm formation. Transcription (mRNA) levels of dlt and ica genes were measured using quantitative polymerase chain reaction, and slimes of S. aureus biofilm were examined with confocal scanning laser microscopy during S. aureus adhesion and biofilm formation. Although hBD­3, vancomycin and clindamycin led to significantly attenuated biofilm formation, their treatment­associated effects on the mRNA expression of dlt and ica were not identical. Vancomycin and clindamycin induced sustained expression of the dlt and ica genes, which may be harnessed to induce biofilm formation. However, hBD­3 did not have a significant affect on the transcription level of dltB during either bacterial adhesion or biofilm formation. Therefore, the mechanism of hBD­3 that regulated the suppression of biofilm formation appears to differ from the mechanisms of vancomycin and clindamycin.

Debriding effect of bromelain on firearm wounds in pigs.

BACKGROUND: Wound excision is the standard treatment for firearm wounds. However, achieving a satisfactory curative effect is difficult because of the traumatic mechanism of high-velocity projectiles. We propose a new therapy by using topical bromelain as a supplement to wound incision for the debridement of firearm wounds. We clarified the debriding effect of bromelain on firearm wounds in pigs. METHODS: In vitro, muscle tissues around the wound track and normal muscle were incubated in bromelain solutions of different concentrations. Tissue hydrolization was estimated by measuring tissue weight and the release of total amino acids. In vivo, the hind limbs of 15 pigs were wounded with high-velocity projectiles. Five groups were classified as follows: wound excision (E), wound incision (I), bromelain (B), incision + bromelain (IB), and control (C). Debriding effectiveness was estimated using bacterial content, histopathologic examination, and wound healing time. RESULTS: In vitro, hydrolization of wound tissue was significantly more intensive than that of normal tissue. Bromelain solution (10 mg/mL) hydrolyzed wound tissue rapidly with minimal proteolysis of normal tissue. In vivo, the wound-track bacterial content of group IB was similar to that of group E and was significantly lower than that of groups I, B, and C. The wound healing time of group IB was also shorter. CONCLUSIONS: Bromelain is effective in the debridement of uncomplicated firearm wounds if used as a supplement to simple wound incision. This new therapy shows notable advantages over conventional surgical debridement as it greatly simplifies the procedures.

[Hepatitis B virus X protein regulates c-met promoter via the ERKs singal pathway in HepG2 cells].

OBJECTIVE: To explore the signal pathway mediating the regulatory effect of Hepatitis B virus X protein (HBX) on c-met gene promoter in HepG2 cells. METHODS: The expression of c-met in HBX-transfected HepG2 cells treated with different signal pathway inhibitors was detected by western blot, the invasion capability of cells was determined by Matrigel invasion assay. RESULTS: ERK inhibitor U0126 inhibited the expression of the c-Met in HBx-transfected HepG2 cells. However, both p38MAPK inhibitor SB203580 and PI-3K inhibitor wortmanin had no effect on expression of the c-Met in HBx-transfected HepG2 cells. Furthermore, the ERK inhibitor U0126 also inhibited the invasiveness of HBX-transfected HepG2 cells. CONCLUSION: HBx induces invasion of HCC via activation of ERK pathway.

[The effect of hepatitis B virus X protein on the c-met promoter activity in HepG2 cells].

OBJECTIVE: To confirm the effect of hepatitis B virus X (HBx) protein on the c-met promoter activity in HepG2 cells. METHOD: The expression of c-met protein was detected by western blot in HBx-transfected HepG2 cells, the human c-met promote activity was checked by luciferase assay using five different constructs with deletion or point mutation. RESULTS: HBx protein stimulated the expression of the c-met in HepG2 cells. The enhanced expression of c-met in HBx-transfected cells was mediated by the activation of AP-2 and SP-1 transcriptional activity at the c-met promoter region (-183bp--100bp), HBx increased the invasiveness of HepG2 cells as determined by Matrigel invasion assay. CONCLUSION: These results suggests that HBx induces the expression of c-met through the activation of AP-2 and SP-1 activity at the promoter region; in addition, our data indicate that HBx stimulates the invasive potential of HepG2 cells.