Objective To investigate the accuracy of NGAL in prediction of acute kidney injury (AKI) complicated by sepsis. Methods Blood and urine samples were collected at different time points in 74 sepsis patients, and 17 AKI patients were got from them.Cysteine Cys C levels were detected with Latex enhanced turbidimetric immunoassay (LETIA). Urine NGAL and Scr levels were detected with solid-phase sandwich enzyme-linked immunosorbent assay and creatinine enzymatic assay respectively. At the same time, 57 non-AKI patients were set as controls. Dynamic changes of urine NGAL and Scr were observed in sepsis patients in test and control group. ROC curve was used to evaluate the performance of AKI diagnosis by urinary NGAL.Results The Scr base line was (59. 38 ±16. 72) μmol/L.The median time of diagnose of AKI was 24 (12, 48) h past-sepsis diagnosis, while the Scr was(100. 35± 28. 26) μmol/L. Of the group, 17 cases of sepsis were diagnosed with AKI, accounting for 23% (17/74) prevalence. In sepsis group, base line value[(0. 61 ± 0. 15) mg/L] of serum Cys C was not upregulated at 2, 4 and 6 h, which was (0. 63 ± 0. 14) mg/L, (0. 68 ± 0. 16) mg/L and (0.65±0. 14) mg/L respectively. As to 8 h [(0. 85 ± 0. 22) mg/L], a slight upregulation was found with no significant difference (t = 1.63, P ＞ 0. 05).A trend of gradual increase of serum Cys C levels was found in sepsis AKI group at 12, 18, 24, 36, 48 and 72 h. A significant difference was found compared with base line (t = 2. 81, 2.98, 3.05, 3.11, 3. 38,3. 17,P ＜0.01). NGAL level[(96.21 ±45.32) μg/L] was significantly higher than base line value [(4. 98 ± 1.65) μg/L]. Subsequently, in each time point from the 2 h to 48 h, a trend of gradual increase in urinary NGAL levels was showed. The differences were significant compared with the baseline values (t =2. 74,2. 83,2. 91,3.04,3.15,3.22,3. 31,3.45,3.57 ,P ＜0. 01). Urinary NGAL levels of sepsis AKI group were significantly higher than those in non-AKI group at different time points with significant difference (t =2. 69,2. 73,2. 84,2. 96,3.02,3. 13,3.29,3.43,3.54,3.22,P ＜0. 01). ROC curve was selected to analyze diagnostic performance of urinary NGAL levels in AKI patients 2 h post-sepsis. Area under ROC curve was obtained as 0. 935, 95% confidence interval was 0. 683-0. 971. When cut-off value of urinary NGAL for patients 2 h post-sepsis was 50 μg/L, the sensitivity, specificity and accuracy were 94. 4%, 87. 5% and 96. 8% in AKI diagnosis respectively. Conclusions The occurrence of AKi can be accurately predicted by urinary NGAL levels 2 h post-sepsis , and its AKI diagnosis time is earlier than that of Scr. Urine NGAL can be used as early marker of AKI complicated by sepsis.

Objective : To analyze the initial displacement of the upper central incisor and stress distribution of periodontal ligament under different torque values of upper incisors under the action of a four-curved auxiliary arch to provide a reliable basis for the safety of clinical application of four-curved auxiliary arches. Methods : A three-dimensional finite element model for torque control of upper anterior teeth with a homemade quadrilateral auxiliary arch was established. Four different states were analyzed: molar ligation without extraction space (group A), microimplant ligation without extraction space (group B), molar recovery with extraction space closure (group C) (the adductive traction force was set at 115 g) and microimplant recovery with extraction space closure (group D) (the adductive traction force was set at 115 g). When four types of torque (0.5 N, 1.0 N, 1.5 N, and 2.0 N) were applied. The initial displacement of upper central incisors and the stress distribution of periodontal ligament in 16 groups (A1-A4, B1-B4, C1-C4, D1-D4) were observed. Results : Under different conditions, as the strength of the four-curve auxiliary arch increases, the maxillary anterior teeth has crown labial inclination and a root lingual inclination. The displacement of the incisor tip increases with the increase in the loading force of the torque auxiliary arch, and the displacement of the incisor root apex increases as the force increases. The difference in incisor-apex displacement distance in A1-A4, B1-B4, C1-C4, D2 and D4 groups increased as the torque force increases, while the difference between the D3 group and D1 and D2 groups decreased slightly. The stress of the cervical periodontal ligament of the upper central incisor did not exceed the stress of the periodontal ligament in the following groups: A1, A2, B1, B2, B3, C1, C2, D1, and D2. The stress of the lip side of the upper central incisor did exceed the stress of the periodontal ligament in the following groups: A3, A4, B4, C3, C4, D3, and D4. In other words, when using the four-curved auxiliary arch as an implant anchorage, the force applied in the absence of extraction space should not exceed 1.5 N, and the force applied in the adduction of extraction space should not exceed 1.0 N. When using the nonimplant anchorage, the force applied in the absence of extraction space and the adduction of extraction space should not exceed 1.0 N. In addition, the range of force should not exceed the maximum stress of the periodontal ligament in the cervical region such that the effective and safe torque movement can be achieved. Under other stress conditions, the stress of the labial and cervical periodontal ligament of the upper central incisor exceeded the stress value (2.6 × 10-2MPa). The stress value of periodontal ligament was 2.6 × 10-2MPa in all groups. Conclusion A four-curved auxiliary arch has a significant effect on the upper anterior teeth, and the use of microimplants can better control root movement such that the crown of upper central incisors cannot be excessively lip inclined.