Objective To improve the purifying method of Jo-1 antigen from rabbit thymus used for detection of anti-Jo-1 antibody by dot-blotting immunoassay(DB).Methods The rabbit thymus glands were cut into pieces,homogenized and extracted by PBS.Total protein was precipitated by acetone to get acetone powder(RTAP).The RTAP was solved in PBS and separated by an by anti-Jo-1 IgG affinity column.Results 5～7 g RTAP was obtained from 100g rabbit thymus glands.There was 19%～24% of protein in RTAP.Jo-1 antigen was enriched around 1900 folds through affinity chromatography,with 2.5% recovery of antigenic activity.In this preparation,there were several bands on SDS-PAGE,but only one band about 50 ku,reacted with anti-Jo-1 antisera on immunoblotting.Dot-blotting also showed that the antigen only reacted with Jo-1 antisera.The purified Jo-1 antigen was not stable for long time,but the antigenic activity could maintain for a long time when there was MgCl2 in the solution.Conclusion Affinity chromatography was a simple and easy method for purifying Jo-1 antigen from rabbit thymus.The antigen purified by affinity chromatography could meet the requirement for detecting Jo-1 antibody bydot-blotting.

Objective:To evaluate the clinical value of 5.0 T ultra-high filed MRI system in assessing intracranial arteries segments and vessel branchers.Methods:This study was a prospective study. Totally 40 consecutive healthy volunteers were recruited from Zhongshan Hospital, Fudan University from September 1, 2021 to November 30, and all participants who underwent either 3.0 T or 5.0 T time-of-flight MR angiography (TOF-MRA) in random order were divided into 3.0 T MR group and 5.0 T MR group with 20 volunteers for each group. Image quality was assessed by Likert 5 scoring systems and signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR),and score in visualization of intracranial arteries [middle cerebral artery (MCA) and its segments, anterior cerebral artery (ACA) and its segments, posterior cerebral artery (PCA) and its segments, lenticulostriate arteries (LA) and pontine artery (PA)] were assessed from 0 to 3 (≥2: good depiction of vessel segment). Quantitative indicators were compared between 2 groups using independent t test or Mann-Whitney U test. Results:Among the 40 subjects, there were 29 males and 11 females, aged 20-69 (50±12) years. SNR and CNR were both significantly higher in 5.0 T MR group than those in 3.0 T MR group (SNR: 187±9 vs 91±4, t=31.59, P<0.001; CNR: 156±7 vs 70±4, t=31.45, P<0.001), but there was no significant difference in subjective scores of image quality between the 5.0 T MR and 3.0 T MR groups [5.0 (4.0, 5.0), 5.0 (5.0, 5.0) points, respectively, Z=-1.23, P=0.218]. In the evaluation of cerebral arteries, the visualizations of the proximal and middle segments of MCA, ACA and PCA was better than those in the 3.0 T MR group, and there was no significant difference in the scores ( P>0.05), while the visualizations of proximal arteries in the 5.0 T MR group were significantly better than those in the 3.0 T MR group ( P<0.05). Furthermore, small vessel branches such as LA and PA in 5.0 T MR group were visualized better than those in 3.0 T MR group ( P<0.001). Conclusion:TOF-MRA by ultra-high filed 5.0-T provides an optimal choice in visualization of distal large arteries and small vessel branches, which could be useful for the diagnosis on cerebral vascular disease.