RESUMEN
OBJECTIVE: The aim of this study was to assess bone quality in patient's preoperative cone beam computed tomography (CBCT) and their relation with marginal bone loss at implant placement sites over follow-up periods. MATERIALS AND METHODS: In this retrospective cross-sectional study, 100 implants were evaluated. The implants had been placed in the maxillary and mandibular edentulous areas. Bone quality at implant placement sites was measured on preoperative CBCTs and then classified by two observers according to Lekholm and Zarb classification. Marginal bone height was then measured on periapical radiographs obtained at baseline and then 6, 12, 18, 24, and 30 months' follow-up periods from a reference point (implant shoulder) to the bone-implant interface. The relation between bone quality and bone loss was assessed. ANOVA was used to compare mean difference among groups and Pearson correlation coefficient to assess the correlation between observers. All statistical analyses were performed at 0.05 significance level using Stata 11 software (StataCorp, College Station, TX, USA). RESULTS: Of 100 implants, 48 were placed in the maxilla and 52 in the mandible. There was no significant difference between bone quality and the mean bone loss at follow-up periods. Using Pearson's correlation coefficient, it was shown that with an increase in bone quality, marginal bone loss was decreased at follow-up periods. CONCLUSIONS: The results confirmed that during the follow-up periods, less bone loss was observed in implant areas with higher bone quality and CBCT is a reliable tool for assessing bone quality at implant placement sites and estimation of subsequent treatment prognosis.
RESUMEN
Application of streptokinase (SK) as a common and cost-effective thrombolytic drug is limited by its antigenicity and undesired hemorrhagic effects. Prior structural/functional and epitope-mapping studies on SK suggested that removal of 59 N-terminal residues led to its fibrin dependency and identified SK antigenic regions, respectively. Following in silico analyses two truncated SK proteins were designed and compared for their fibrin specificity and antigenicity with the full-length SK. Computer-based modeling was used to predict the effect of vector (pET41a)-born protein tags on the conformation of SK fragments. SK60-386, SK143-386 and full-length SK (1-414) were separately cloned, expressed in BL21 E. coli cells and confirmed by Western-blotting. Functional activity of the purified proteins was evaluated with chromogenic and clot lysis assays and their antigenicity was tested by ELISA assay using rabbit anti-streptokinase antibody. As expected, chromogenic bioassay showed a major activity decline for SK60-386 and SK143-386 (83 and 91 percent, respectively), compared to SK1-414. However, in clot lysis assay, which is a fibrin-dependent pharmacopoeia-approved test, SK60-386 and SK143-386 were respectively 35 and 31 percent more active though lysed the clots slower than full-length SK. Antigenic analysis also indicated significant decrease in ELISA signals obtained for truncated proteins compared to SK1-414 (45 and 28 percent less reactivity for SK143-386 and SK60-386, respectively, p < 0.0001). The results of this study for the first time pointed to SK143-386 and SK60-386, as improved SK derivatives with increased fibrin-selectivity and decreased antigenicity as well as acceptable bioactivity profiles in a pharmacopoeia-based analysis, which deserve more detailed pharmacological studies.