Background The ultrastructure change and growth of corneal nerve after laser in situ keratomileusis (LASIK) are some influent factors to the stability of tear film and the sensibility of cornea.Some relevant studies are lack up to now.Objective This study is to observe the changes of ultrastructure of corneal epithelium and regeneration of corneal nerve fiber.Methods LASIK was performed on the lateral eyes of 48 New Zealand white rabbits.Rabbit eyes were excavated at instant in postoperation,one day,seven days,one,three and six months after LASIK.Change of corneal ultrastructure and corneal nerve staining were examined under the scanning electron microscope (SEM) and transmmision electron microscope (TEM) at the time points mentioned above.The numbers of microvilli of corneal epithelial cells in different postoperative time were analyzed.10% AuCl was used to evaluate the growth status of corneal nerve in different time after LASIK.Results Irregularity of microvillus of corneal epithelial cells,degrease of cell density were seen under the TEM and some cavities could been observed in the instant of postoperation.The connection abnormality of intercells,dropsy and rupture of microvillus were presented under the SEM,However,the ultrastructure of corneal epithelial cells was almost normal in 7 days after LASIK.The numbers of microvillus in corneal epithelial cells were significantly declined in the postoperative instant group compared with preoperative group (P＜0.05),but no evidently difference was found in postoperative 1 day and 7 days groups compared with preoperative group(P＞0.05).Corneal nerve staining showed that in 1 day after surgery,nerve plexus was deprivation and boundary of nerve injury was clear and nerve fibers were cut off.After one month some reborn nerve fiber grew into the cornea flap.Reborn corneal nerve fiber can be seen at center laser ablation area after six months of LASIK.Conclusion The ultrastructure change of corneal epithelial cells in the early stage after operation may be a important factor causing dry eye symptom following LASIK.The growth fashion of corneal nerve fibers is from the cutting edge to the center of corneal flap.

Objective To explore the relationship between levels of serum 25-(OH) D3 and changes in Th1/Th2 cell balance in infants with recurrent wheezing.Methods Sixty cases of infants with recurrent wheezing were involved and 60 cases of healthy children were selected as controls.Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of serum 25-(OH) D3 and double-antibody sandwich (ABC-ELISA) was used to detect the serum levels of interferon-γ(IFN-γ),interleukin (IL)-4,IL-13,and then the relationship between the levels of serum 25-(OH) D3 and changes in Th1/Th2 balance in infants with recurrent wheezing were explored.Results Serum 25-(OH) D3 levels decreased significantly in the infants with recurrent wheezing group compared with those of the healthy control group [(18.24 ± 5.64) μg/L vs (37.85 ± 7.78) μg/L] (t =15.810,P =0.000).Serum IFN-γ levels decreased significantly in the infants with recurrent wheezing group compared with those of the healthy control group [(11.20 ± 2.08) ng/L vs (20.68 ± 3.87) ng/L] (t =16.700,P =0.000).In contrast,serum IL-4,IL-13 levels increased significantly in the infants with recurrent wheezing group compared with those of the healthy control group[IL-4:(28.61 ±6.44) ng/L vs (22.14±5.29) ng/L;IL-13:(20.02±4.83) ng/L vs (17.72± 4.06) ng/L] (t =6.201,P =0.000 ; t =2.829,P =0.006).Th1/Th2 in the infants with recurrent wheezing group were lower than that those of the healthy control group,and there was statistically significant difference between two groups(0.41 ± 0.12 vs 1.00 ± 0.36) (t =11.796,P =0.000).Serum 25-(OH) D3 levels were negatively correlated with Th1/Th2 in the infants with recurrent wheezing(r =-0.649,P =0.000).There were no correlation between serum 25-(OH) D3 levels and Thl/Th2 in the healthy control group(r =-0.217,P =0.096).Conclusions Low serum 25-(OH) D3 may be the risk factor for recurrent wheezing in infants.Serum 25-(OH) D3 levels were negatively correlated with Th1/Th2 in the infants with recurrent wheezing group,which show that recurrent wheezing in the infants is closely related to allergic reaction.

Objective : The present study observed the clinical effects on reattachment and pulpotomy of young crown-fractured and pulp-exposed permanent incisors. Methods : In a one-year retrospective clinical observation study, 30 traumatic intact segments of permanent incisors with crown fracture and pulpal exposure were treated using a pulpotomy and reattachment technique with an enamel-dentin luting agent and composite resin. Results : The number of subsequent visit teeth was 30, 29, 25 at 1, 3, 6 months follow-up respectively. The pulpotomy success rates were 100% at 1 month, 93.1% at 3 months, 93.1% at 6 months. The retention rates using the reattachment technique were 100% at 1 month, 100% at 3 months, 100% at 6 months. Conclusion Pulpotomy is the preferred method of preserving live pulp after pulpal exposure of young permanent incisors, and the clinical effect is prominent. The fragment reattachment technique is an effective middle- and short-term method for temporary restoration of young crown-fractured permanent incisors.