BACKGROUND: The conical telescopic crown denture has a better long-term effect on dentition defects of few remaining teeth than the traditional removable denture. However, there are few studies to analyze the application of these two kinds of repair methods using the finite element method. OBJECTIVE: To compare the stress distribution of the isolated abutment tooth repaired using the conical telescopic crown denture and traditional removable denture. METHODS: Two-dimensional images of the mandible and dentition in healthy adults were scanned by CT. Three-dimensional finite element models of conical telescopic crown denture and traditional removable denture were established in the mandible only with the bilateral canines. Under the same vertical and oblique loadings, the maximum equivalent stress of the abutment, periodontal membrane or edentulous alveolar ridge was compared between two repair methods. RESULTS AND CONCLUSION: Under the vertical and oblique loadings, the total stress of abutment and periodontal membrane in the traditional removable denture was higher than that in the conical telescopic crown denture and the stress in the corresponding ring was concentrated obviously; the total stress of edentulous alveolar ridge in the conical telescopic crown denture was slightly larger than that in the traditional removable denture, but the stress was wel -distributed and concentrated in a smal area. Under the oblique loading, the total stress of abutment, periodontal membrane and edentulous alveolar ridge was higher than that under the vertical loading in these two dentures, and the stress was concentrated in the periodontal membrane of lingual neck, but the total stress in the traditional removable denture was larger, with a wider concentration range. These findings indicate that the stress on the supporting tissue of conical telescopic crown denture is more evenly distributed within a smal er range than that of traditional removable denture, and the former is more fit for the health of abutment, periodontal tissues and edentulous alveolar ridge.

Objective To investigate the effect and the potential mechanisms of low molecular polysaccharide from agaricus blazei (LMPAB) on H2O2-induced oxidative injury in hippocampal neuronal cells of rats.Methods Hippocampal neuronal cells were isolated from SD rats (24 h) and grew in culture.Cultured cells were divided into normal control group (added the same amount of nutrient solution), model control group (added 500 μmol·L-1H2O2 solution) and LMPAB high, medium, low dose groups (added 20,10,5 mg·L-1 LMPAB solution, respectively, then added 500 μmol·L-1 H2O2 solution each).The hippocampal neuron cell activity was detected with MTT method.The hippocampus neuron mitochondrial membrane potential (MMP) was detected by flow cytometry.According to the reagent instruction methods, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities were detected.Results The activities of cell, CAT, SOD, GSH-PX and MMP in normal control group and the LMPAB high dose group were significantly higher than those of model control group (P<0.01);The content of MDA in normal control group and LMPAB high dose group was significantly lower than that of model control group (P<0.01).Conclusion The protective effect of LMPAB on hippocampal neurons with H2O2-induced injury may be related with the mechanism of enhancing the neuronal antioxidative capacity.

Objective To prepare PTD4-Cu,Zn-SOD fusion protein.Methods The recombinant plasmid of pET 1 6b-Cu,Zn-SOD and pET16b-PTD4-Cu,Zn-SOD was transformed into Escherichia coli BL21 (DE3).Isopropyl β-D-1-thiogalactopyranoside was then added at a final concentration of 0.84 mmol/L,and the cells were incubated for 4 h to induce the expression of Cu,Zn-SOD and PTD4-Cu,Zn-SOD fusion protein.Lysozyme and ultrasound were used to lyse the bacteria,the supernatant was collected for 15％ SDS-PAGE to analyze the expression of the target protein.Ni-NTA His bind resin was used to purify Cu,Zn-SOD protein and PTD4-Cu,Zn-SOD fusion protein under natural conditions.Western blot was used to identify the target protein.Results The results of Western blot showed that the purity of the target protein was about 90％,and the Cu,Zn-SOD protein with a molecular weight about 19 kDa and the PTD4-Cu,Zn-SOD fusion protein with a molecular weight about 20 kDa were found.Conclusion PTD4-Cu,Zn-SOD fusion protein is prepared successfully.

Hospitals today are confronted with new challenges in environmental hygiene management. Based on recent literatures and norms at home and abroad, this review analyzed such challenges and defects found in the environmental hygiene management of hospitals in China. The problems include but are not limited to the following: incomplete environmental management system and norms, insufficient staffing and funding support, lack of HR management mechanism in terms of employment, training, appraisal and reward/penalty, as well as poor hygiene awareness of hospital environmental services staff. In view of these problems in the hospitals, the authors provide specific countermeasures as follows: establishing new environmental hygiene management models, improving management mechanisms, creating positive and normalized cultural atmosphere for environmental infection control, and applying informatization to upgrade environmental hygiene quality. These measures are expected to serve as references for improving surrounding hygiene of patients.

Dysphagia is often associated with incoordination between breathing and swallowing, resulting in the occurrence of aspiration, cough and aspiration pneumonia. This article reviewed the specific physiological mechanisms of respiration and swallowing and their clinical applications, which aimed to focus on the relationship between respiration and swallowing systems in health and disease, and to explore its guiding value in the clinical treatment of dysphagia.