Comparison of corneal biomechanical parameters between keratoconus and laser corneal refractive surgery / 眼科新进展

Objective To measure biomechanical parameters of the cornea after keratoconus and laser corneal refractive surgery by Scheimpflug noncontact tonometry (Corvis ST),and analyze the changes and differences in these parameters.Methods From April 2011 to November 2016,63 patients (96 eyes) with clinically diagnosed as keratoconus were selected as the keratoconus group,and 60 patients (120 eyes) underwent laser corneal refractive surgery between November 2016 to March 2017 were selected as postoperative cornea group,and totally 51 healthy person (102 eyes) who received physical examination during the same period were selected as healthy cornea group.Scheimpflug noncontact tonometry (Corvis ST) was performed to measure the length of appl 1,length of appl 2,velocity of appl 1,velocity of appl 2,maximum deformation amplitude,apex distance and radius of curvature in the three groups.Total comparison of biomechanical parameters was performed using ANOVA test among the three groups,while pairwise comparison was performed to analyze the difference of these parameters by SNK methods.Pearson or Spearman correlation analysis was applied to assess the differences in corneal morphological and biomechanical parameters.Results There was no significant difference in length of appl 1,length of appl 2 of the three groups (all P ＞ 0.05).And velocity of appl 1 in the keratoconus group was significantly higher than that of the healthy cornea group [(0.189 ± 0.230) m · s-1 vs.(0.151 ± 0.017)m · s-1] (P ＜ 0.05).As for velocity of appl 2,the keratoconus group was larger than the healthy cornea group,both which were larger than the postoperative cornea group,and the differences were significant (all P ＜ 0.05).And this was true of maximum deformation amplitude in the three groups,with the significant differences(all P ＜ 0.05).The apex distance in the keratoconus group was significantly longer than that in the healthy cornea group (P ＜ 0.05).The radius of curvature of the keratoconus group,postoperative cornea group and healthy cornea group were (5.696 ± 0.881) mm,(7.129 ± 0.681) mm and (7.012 ± 0.728) ram,respectively,which approached significant differences(all P ＜ 0.05).There was significant correlation between the anterior surface refractive power (Km) and apex distance and radius of curvature in the keratoconus group (r =-0.205,0.1 84;P =0.023,0.041),and maximum posterior surface elevation had a statistically significant correlation with velocity of appl 2,maximum deformation amplitude and radius of curvature (r =-0.579,-0.307,0.256,P =0.022,0.002,0.000).For the eyes in the postoperative cornea group,there were no significance correlation between the anterior surface refractive power (Km) and biomechanical properties (P ＞ 0.05),but significant correlation with length of appl 2 (r =-0.297,P =0.026).There were no significant correlation between maximum posterior surface elevation and biomechanical properties (P ＞ 0.05).Conclusion The corneal biomechanical parameters are decreased in eyes after keratoconus and laser corneal refractive surgery,and Corvis ST can become an auxiliary examination tool for earlier diagnosis of secondary keratoconus after corneal refractive surgery.

The Functional Motif of SARS-CoV S Protein Involved in the Interaction with ACE2 / 中国病毒学

SARS-CoV is a newly discovery pathogen causing severe acute respiratory problems.It has been established that the S protein in this pathogen plays an important rule in the adsorption and penetration of SARS-CoV into the host cell by interaction with the ACE2 receptor.To determinant which functional motif of the S protein was involved in the interaction with ACE2,seven truncated S proteins deleted from the N or C terminal were obtained by an E.coli expression system and purified by column chromatography to homogeneity.Each truncated S protein was fixed on to the well of an ELISA plate and an interaction was initiated with the ACE2 protein.The adsorption were quantified by ELISA,and the results indicated that amino acids from 388 to 496 of the S protein was responsible for the interaction with the ACE2 receptor,and the interaction could be completely disrupted by an antibody specific to these amino acids.Deletions adjacent to this domain did not appear to have a significant impact on the interaction with ACE2,suggesting that the S protein of SARS-CoV could be developed as a vaccine to prevent the spread of SARS-CoV.

The purification of HBV full-length PreS protein in Pichia pastoris / 生物工程学报

The Pichia pastoris strain GS115-PreS could produce a high expression level of full-length PreS protein that secreted to the supernatant after methanol induction in the fermentation. The Western blot analysis showed a single band with expected molecular mass of 48kD and that the major component of the particles was the full-length PreS protein (PreS1 + PreS2 + S) and small envelope protein (S) of 48 and 28 kD, respectively. Electron microscopy image showed PreS particles with 30 nm in diameter. The supernatants of the fermentation were desalted and concentrated. Purified PreS protein was obtained by DEAE-SFF anion exchange column chromatography and the PreS particles were obtained by ultracentrifugation and sucrose density gradient. The ELISA assay results proved that both full-length PreS protein and particles showed high immunogenicity and specificity. P/N ratio further demonstrated that the immunogenicity of the particles is higher than the full-length PreS protein.

Expression of Hepatitis C Virus NS5A Gene In E.coli and Its Application in HCV Antibody Detection / 中国病毒学

Full-length NS5A gene of the hepatitis C virus was amplified by PCR using plasmid pBAC25 containing HCV nonstructural gene as template. The amplified fragment (about 1.34 kb) was cloned into plasmid pQE32, and the recombinant plasmid pQENS5A was expressed in JM109 strain. The NS5A protein was purified by NiSO4 metal chelating resin, and characterized by Western-blot. Its antigenecity was determined by ELISA. The positive detection rate of anti-NS5A was 75% (69/92) in ninety-two clinic sera. The positive rate of anti-NS5A was 82.5% (33/40) in fourty positive standand sera, and the negative rate of anti-NS5A was 100% (40/40) in fourty negative standand sera. The results showed that the Full-length NS5A proteinn had the higher sensitivity and specificity in the detection of HCV antibody in sera, we suggested that NS5A protein was a useful antigen for blood screening.