BACKGROUND:The in vivo degradation process of chitosan/hydroxyapatite composite porous scaffolds is not very clear. Research on the effects of rat osteoblasts and degradation products is less.
OBJECTIVE:To analyze the biocompatiblity of rat osteoblasts with degradation products of chitosan/hydroxyapatite composite porous scaffolds.
METHODS:The second generation of cultured rat osteoblasts were respectively cultured in the extract of degradation products of chitosan/hydroxyapatite composite scaffolds (experimental group) and Dulbecco’s modified Eagle’s medium containing 10%fetal bovine serum (control group). At 2, 4, 6, 8, 10 days of culture, cel counting was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Alkaline phosphatase activity was measured by the recommended method of determination of the Federation, and total protein was determined by BCA method.
RESULTS AND CONCLUSION:The proliferation speed, alkaline phosphatase activity, total cel ular protein synthesis and ratio of alkaline phosphatase to total protein in rat osteoblasts cultured in the experimental group were significantly higher than those in the control group (P<0.05). This experiment showed that the degradation products of chitosan/hydroxyapatite composite porous scaffolds cannot only promote rat osteoblast adhesion, growth and proliferation, but also enhance its ossification function, with good biocompatibility.

Objective:To determine the correlations of single nucleotide polymorphisms (SNPs) with atrial fibrillation (AF) in the Chinese Han population from the central plains.Methods:A total of 168 hospitalized patients,including 56 AF and 112 controls,were recruited in this case-control study.The clinical data were obtained from the medical records.All 5 SNPs,rs337711 in KCNN2,rs11264280 near KCNN3,rs17042171 near PITX2,rs6771157 and rs6795970 in SCN10A,were genotyped using amplification refractory mutation system-polymerase chain reaction or direct sequencing.The x2 test was used to compare categorical variables and preliminarily examine correlations between the genotype frequencies and AF.Subsequently,a logistic regression model was constructed to determine the associations between the SNPs and AF based on the above screened results.Odds ratios (ORs) and 95％ confidence interval (CI) were calculated to assess the strength of the correlations.Moreover,we downloaded the genotype data from the HapMap Project for linkage disequilibrium analysis ofrs17042171.Results:AF patients were likely to be of older age and longer left atrial diameter and had more coronary artery disease and higher hypertension compared with the control group (P＜0.05).Among the 5 SNPs,the frequency distribution of genotype AA for rs17042171 was significantly different between the AF and control groups (P＜0.05).After adjusting for several covariates,there was still a high risk ratio in patients with the AA genotype compared with the AC+CC genotype (OR:5.591,95％CI 2.176 to 14.365,P-B＜0.008).Similarly,stratification analysis on the AA genotype demonstrated significant differences between rs17042171 and persistent AF.However,there were not significant correlations between AF and the control groups for the other 4 SNPs (P＜0.05).Conclusion:Rs17042171,near PITX2 on chromosome 4q25,is associated with AF susceptibility in the Chinese Han population from the central plains,suggesting that this SNP can provide a new strategy for clinical diagnosis in AF patients.

Ulcerative Colitis (UC) has been reported to be related to Porphyromonas gingivalis (P. gingivalis). Porphyromonas gingivalis peptidylarginine deiminase (PPAD), a virulence factor released by P. gingivalis, is known to induce inflammatory responses. To explore the pathological relationships between PPAD and UC, we used homologous recombination technology to construct a P. gingivalis strain in which the PPAD gene was deleted (Δppad) and a Δppad strain in which the PPAD gene was restored (comΔppad). C57BL/6 mice were orally gavaged with saline, P. gingivalis, Δppad, or comΔppad twice a week for the entire 40 days (days 0-40), and then, UC was induced by dextran sodium sulfate (DSS) solution for 10 days (days 31-40). P. gingivalis and comΔppad exacerbated DDS-induced colitis, which was determined by assessing the parameters of colon length, disease activity index, and histological activity index, but Δppad failed to exacerbate DDS-induced colitis. Flow cytometry and ELISA revealed that compared with Δppad, P. gingivalis, and comΔppad increased T helper 17 (Th17) cell numbers and interleukin (IL)-17 production but decreased regulatory T cells (Tregs) numbers and IL-10 production in the spleens of mice with UC. We also cocultured P. gingivalis, Δppad, or comΔppad with T lymphocytes in vitro and found that P. gingivalis and comΔppad significantly increased Th17 cell numbers and decreased Treg cell numbers. Immunofluorescence staining of colon tissue paraffin sections also confirmed these results. The results suggested that P. gingivalis exacerbated the severity of UC in part via PPAD.
Animals ; Colitis, Ulcerative/microbiology* ; Mice ; Mice, Inbred C57BL ; Porphyromonas gingivalis/pathogenicity* ; Protein-Arginine Deiminases ; Virulence Factors