Construction and Characterization of a PGN_0297 Mutant of Porphyromonas gingivalis: Evidence of the Contribution of PGN_0297 to Gingipain Activity.

The periodontal pathogen Porphyromonas gingivalis shows colonial pigmentation on blood agar and produces gingipains (Kgp, RgpA, and RgpB), cysteine proteases involved in an organism's virulence and pigmentation. We showed previously that deletion of the PGN_0300 gene abolished the pigmentation activity and reduced the proteolytic activity of gingipains. The role of the PGN_0297 gene, which consists of an operon with the PGN_0300 gene, is unclear. Herein we examined the effect of PGN_0297 gene deletion on the pigmentation and proteolytic activities and transcriptional levels of gingipains. A PGN_0297 gene deletion mutant (ΔPGN_0297) did not exhibit the pigmentation. The proteolytic activity of the gingipains was decreased in the culture supernatant and on the cell surface of ΔPGN_0297. The mutant ΔPGN_0297 failed to attenuate Akt phosphorylation at Thr308 and Ser473, but both phosphorylations were attenuated in the wild-type and its complementation strain. The deletion of PGN_0297 gene did not substantially affect the transcriptional levels of the gingipain genes kgp, rgpA, and rgpB. Taken together, these results indicate that PGN_0297 is closely involved in the secretion and maturation of gingipains.

The attachment and collagen deposition of human gingival fibroblasts on titanium surface with different topography / 实用口腔医学杂志

Objective:To study the attachment and collagen deposition of human gingival firbroblasts (HGFs) on titanium surface with different topography.Methods:Titanium surfaces created by machining(group M),electrolytic etching(group ECE) and electrolytic etching and acid etching(group ECA) were observed by SEM.HGFs cultured on the titanium surfaces were observed by laser scanning confocal microscope.Attachment of the cells was examined by comparing the numbers of attached to detached cells,respectively.Collagen production and deposition were examined via a Sirius red-based stain assay and confocal laser scaning microscopy.Results:The surface rouphness (μm) of group M,ECE and ECA was 0.867 5 ± 0.136 8,1.749 8 ± 0.355 1 and 1.671 4 ± 0.297 0 (P＜ 0.05) respectively,Cell attachment was significantly weaker on machined surface than on ECE and ECA surfaces,while which was weaker on ECE surface than on ECA surface.Collagen production was the highest on the machined surface,followed by that on ECE and ECA surface,Collagen deposition displayed a parallel pattern on the machined surface,while it was multidirectional on the ECE and ECA surfaces.Conclusion:The ECA surface of titanium may be beneficial to HGFs attachment,the machined surface may promote collagen deposition.

A retrospective clinical study of immediate implantation and delayed implantation in molar area / 实用口腔医学杂志

Objective:To compare the changes of marginal bone resportion between immediate implantation and delayed implantation after 12 to 24 months of definitive prostheses finished.Methods:41 patients were recruited and divided into immediate implant placement group(n =20) and delayed implant placement group(n =21).All implants were evaluated via radiograph after surgery,6 months after implantion,1 year and 2 years after prostheses placement respectively,the height of marginal bone was measured 6 month after implation,1 year and 2 years after prostheses placement.Results:After 6 month,1 year and 2 year the mesial marginal bone attachement (MBA) of immediate implant placement group increased by (1.35 ± 1.12),(2.16 ± 1.73) and (2.53 ± 1.65) mm,the distal by (1.46 ± 1.17),(1.94 ± 1.16) and (2.32 ± 1.68) mm,respectively (among the 3 time points of examination,P ＜ 0.05).As for the delayed implantation group,in the mesial area MBA increased by (-0.52 ± 0.47),(-0.69 ± 0.58) and (-0.97 ± 0.78) mm,in the distal area by (-0.46 ± 0.44),(-0.60 ± 0.45) and (-0.72 ± 0.63) mm (among 3 time points,P ＞ 0.05).Conclusion:Immediate implantation is superior to delayed implantation for marginal bone attachement of dental implant.

Clinical characteristics of infective endocarditis: analysis of 368 cases / 中华心血管病杂志

<p><b>OBJECTIVE</b>This retrospective study is performed to analyze the epidemiological and clinical features of patients with infective endocarditis (IE) hospitalized in Fuwai Cardiovascular Hospital during the latest 7 years.</p><p><b>METHODS</b>This retrospective study included a cohort of 368 infective endocarditis patients hospitalized in Fuwai Hospital form August 2005 to August 2012. Predisposing cardiac diseases, causative organisms, clinical features and outcomes were analyzed. Risk factors related to outcome including NYHA classes, causative organisms and complications, were evaluated.</p><p><b>RESULTS</b>Among the IE patients, 6.8% (25/368) patients had rheumatic heart diseases 31.8% (117/368) had congenital heart diseases, 22.8% (84/368) were post-PCI or operative endocarditis and IE developed in 14.1% (52/368) patients without previous cardiac diseases. Blood culture positive rate was 46.2% (170/368). Streptococci viridians [27.6% (47/170) ]were the most common causative organisms, followed by coagulase-negative staphylococci [15.9% (27/170) ]. Fever and cardiac murmur were the most common clinical presentations. Congestive heart failure was the most common complication [87.8% (323/368)]. Systemic and pulmonary embolism occurred in 16.0% patients, 80.9% IE was detected by echocardiography. In-hospital mortality rate was 6.7%, mostly due to refractory congestive heart failure and sepsis. Subgroup analysis showed that incidence of post-PCI or operative endocarditis was significantly higher in IE patients hospitalized after 2009 compared to IE patients hospitalized before 2009 (27.5% vs. 19.2%, P < 0.05) . Higher incidence of staphylococcal infection was evidenced in mechanical valves than in native valves (44.4% vs. 19.8%, P < 0.05).</p><p><b>CONCLUSION</b>During the past decade, there is a significant change on epidemiology and clinical features of IE in China. Incidence of post-surgical and interventional IE increased significantly. Staphylococcal and Gram negative bacilli infection are major pathorganisms of endocarditis of mechanical valves. Due to the lower positive rate of blood culture, echocardiography serves as the most important diagnostic tool for infective endocarditis.</p>