A fitting method of calculating local helix parameters of proteins based on dual quaternions registration fitting (DQRFit) is proposed in this paper. First, the C and N atom coordinates of each residue in the protein structure data are extracted. Then the unregistered data and reference data are constructed using the sliding windows. The square sum of the distance of the data points before and after registration is regarded as an optimization goal. We calculate the optimal rotation matrix and the translation vector using the dual quaternion registration algorithm, and get the helix parameters of the secondary structure which contain the number of residues per turn(τ), helix radius(ρ)and helix pitch(p). Furthermore, we can achieve the fitting of three-helix parameters of τ, ρ, p simultaneously with the dual quaternion registration, and can adjust the sliding windows to adapt to different error levels. Compared with the traditional helix fitting method, DQRFit has some advantages such as low computational complexity, strong anti-interference, and high fitting accuracy. It is proven that the precision of proposed DQRFit for α helix detection is comparable to that of the dictionary of secondary structure of proteins (DSSP), and is better than that of other traditional methods. This is of great significance for the protein structure classification and functional prediction, drug design, protein structure visualization and other fields in the future.
Objective To assess the therapeutic effect of sulodexide for diabetic patients with early nephropathy. Methods A total of 60 patients with early diabetic nephropathy (albuminuria: 30 to 300 mg/24 h, male/female: 30/30, mean age: 51.23 years, mean course of disease: 12.9 years) were randomized equally into three groups: the routine treatment group, cozaar group (50 mg qd, po for 12 weeks) and sulodexid group (600 LSU qd, iv or im for 4 weeks, 250 LSU bid, po for 8 weeks). The levels of urinary albumin excretion rate (UAER), urea nitrogen and creatinine were determined. Results After three months of treatment, the level of UAER was decreased significantly in both the sulodexide group and cozaar group (Plt;0.01), but not in the routine treatment group (Pgt;0.05). The level of UAER was reduced by 34.04% and 33.62% in the cozaar group and the sulodexide group, respectively. Significant difference was noted in the level of UAER between the cozaar/sulodexide groups and the routine treatment group (Plt;0.01), but no significant difference was observed between cozaar group and sulodexide group (Pgt;0.05). Conclusion Sulodexide could decrease the level of UAER in patients with early diabetic nephropathy. It has similar efficacy to cozaar.