The gene nhaA encodes functional protein that may play an important role in salt tolerance of Escherichia coli In order to study bacteria salt tolerance, a pair of primers were designed according to public nhaA sequence and was used to amplify 1 1kb DNA fragment with PCR The nhaA gene from E coli DH5?was cloned into a T vector and sequence analyses reveal that the cloned fragment contains entire nhaA gene coding region To apply the method of homology analysis,the result shows that many kinds of bacterium have nhaA gene, such as E coli K12, E coli O157:H7, Salmonella typhimurium and Salmonella enterica , et al This analysis suggests that nhaA gene lie generally in bacterial; and it has intimate relation with salt tolerance of E coli that may be of great importance in improvement of the salt tolerance of plant

Objective To explore the relationship between responsibility and social adaptation of the left-behind middle school students and to provide evidence for mental health education of left-behind children.Methods 290 left-behind middle school students were selected by cluster-random-sampling.All of them were assessed by the middle school students' social adaptability scale (SAS-SSS),the inventory of parent and peer attachment (IPPA) and the scale of high school students' responsibility.Results The correlation between responsibility,attachment behavior and social adaptation of left-behind middle school students were significant(r=0.39,r=0.56,P＜0.01).There were significant differences between gender on the responsibility(male(202.64±26.78) vs female(212.67±23.24)).Regression analysis showed that mother attachment,overall responsibility,general responsibility and special fault responsibility could predict the social adaptation(P＜0.05).Responsibility and its factors played a mediating role between attachment and adaptation,taking 52.1％,20.1％,30.8％,9.1％,47.9％,40.7％ proportion of the total effect.Conclusion Responsibility is an important factor affecting the social adaptation of left-behind middle school students.

To provide a foundation for the development of rapid and specific methods for the diagnosis of rabies virus infection,anti-rabies virus monoclonal antibodies were prepared and rabies virus nucleoprotein and human rabies virus vaccine strain (PV strain) were used as immunogens to immunize 6-8 week old female BALB/c mice.Spleen cells and SP2/0 myeloma cells were fused according to conventional methods:the monoclonal cell strains obtained were selected using the indirect immunofluorescence test; this was followed by preparation of monoclonal antibody ascitic fluid; and finally,systematic identification of subclass,specificity and sensitivity was carried out.Two high potency and specific monoclonal antibodies against rabies virus were obtained and named 3B12 and 4A12,with ascitic fluid titers of 1∶8000 and 1∶10000,respectively.Both belonged to the IgG2a subclass.These strains secrete potent,stable and specific anti-rabies virus monoclonal antibodies,which makes them well suited for the development of rabies diagnosis reagents.

Purpose To study the clinicopathologic features and differential diagnosis of serous microcystic adenoma of pancreas ( SMAP) . Methods Immunohistochemical study was carried out, and the clinical and pathologic features were evaluated in 11 cases of SMAP, and review the literatures. Results The age of onset of 11 cases of SMAP ranged from 41~68 years ( average=55 years) . All of them were females. The clinical presentations were right upper abdominal pain, nausea, vomiting and weight loss. Five tumors located in the pancreas head (45. 5%). Grossly, ten cases were solitary, one case was multiple. The boundary of tumor was clear, the cut surface of tumor was honeycomb. Histologic examination showed that the tumors were made up of small sized capsule wall lining of single-layer flat or cube epithelial cell. The cytoplasm was clear, nucleus was small and no atypical features. Immunohistochemical study showed that all of the 11 cases were positive for CK, CK7, CK18, CK19, EMA, 3 cases were positive for NSE,α-ACT, all of the 11 cases were negative for CgA, Syn, vimentin, TG, Calretinin. Ki-67<1%. Vascular vessels were positive for D2-40 and CD34. Conclusions SMAP is a very rare benign tumor of pancreas. It should be distinguished from oligo-cystic cystadenoma, pseudocyst, mucinous cystadenoma, lymphangioma and capillary hemangioma, mesothelioma.

Objective To determine the expression of cathepsin L2 (CTSL2)and evaluate its activity in skin lesions of seborrheic keratosis (SK),to observe the ultrastructural changes of melanosomes in the skin lesions of SK,and to estimate the effect of CTSL2 on the degradation of melanosomes.Methods Twenty patients with SK were enrolled from the Department of Dermatology,Renmin Hospital of Wuhan University.The lesional tissue and the perilesional normal skin were biopsied from each patient.Among 15 of the 20 patients,hematoxylin and eosin (HE)staining and Fontana-Masson silver staining were performed to observe the distribution of melanin granules,transmission electron microscopy (TEM)was conducted to observe the ultrastructural changes of melanosomes,and immunohistochemical staining was performed to estimate the cellular proliferative activity.RT-PCR and fluorogenic substrate cleavage assay were performed in the other 5 patients to determine the mRNA expression of CTSL2 and evaluate its activity,respectively.Sucrose density gradient ultracentrifugation was performed to isolate and purify melanosomes from the retinal pigment epithelium (RPE) harvested from a discarded eyeball of a 35-year old male patient with informed consent.The purified melanosomes were incubated with epidermal lysates of SK lesions,and TEM was used to observe the changes in the membrane structure of melanosomes.Statistical analysis was carried out by paired t test,and a P value ＜ 0.05 was considered statistically significant.Results A large number of melanin granules were deposited in SK lesions,while the linear deposition of melanin granules was only seen in the basal layer of the normal skin.TEM showed that the percentage of damaged melanosomes was much higher in the normal skin (49.00％ ± 4.00％) than in the SK lesions (24.33％ ± 3.06％)(t =8.49,P ＜ 0.05).RT-PCR revealed that the mRNA expression and activity of CTSL2 were both significantly lower in the SK lesions than in the normal skin (mRNA:0.35 ± 0.09 vs.0.43 ± 0.08,t =3.17,P ＜ 0.05;activity:17.46 ± 0.45 vs.28.78 ± 0.58,t =34.29,P ＜ 0.05).Moreover,TEM also showed that the percentage of damaged melanosome was lower in the SK lesion lysate-treated group (32.33％ ± 4.93％) than in the normal skin lysate-treated group (43.00％ ± 2.65％,t =3.30,P ＜ 0.05).Conclusion Decreased expression of CTSL2 in the SK lesions can affect the degradation of melanosomes by keratinocytes.However,whether CTSL2 directly takes part in the pathogenesis of SK or not is still needed to be further confirmed.

Objective:To investigate the role and influencing factors of case design in PBL teaching.Methods:Thirty-two six-year-program undergraduates from the Department of Medicine of Peking University in batch 2014 and batch 2015 were selected as the subjects. PBL teaching was used in the practice class of experimental diagnostics. The feedback effects of four times PBL courses were analyzed by collecting questionnaires for teachers, students, and supervisors. The data obtained from the five-point questionnaire and the question-and-answer questionnaire were analyzed by one-way ANOVA and statistics respectively. Then the problems in case preparation process are discussed and the experience of case design is summarized. SPSS 13.0 was used in this study.Results:The 5-point questionnaire showed that the average score of anemia PBL course was the highest among students' self-evaluation and mutual evaluation of teachers and students (4.84 points, 4.79 points), with statistical significance compared with other courses ( P<0.05). The question-and-answer questionnaire survey showed that 93.75% of the students generally agreed with the teaching model of anemia cases; 78.13% and 59.38% of the students believed that it was difficult to set up cases of infection and coagulation, which affected the classroom effect; and 50% of the supervisors thinked that the students' level should be taken into account in case design and oral expression should be avoided. Conclusion:Case design is the key to PBL teaching. Summarizing the experience of case design can lay a good foundation for the establishment of PBL teaching database.

Objective:To compare the alveolar cortical bone density and thickness of jaw bones between teenagers (12-18 years of age) and adults(19-48 years of age).Methods:Spiral computed tomographic images of 60 cases were obtained from the subjects with the ages of 12 to 48 years(27 Males and 33 females,35 teenagers and 25 adults).Buccal cortical bone thickness and density in Hounsfield units were measured at 12 interradicular sites and to a depth of 14 mm.Results:The alveolar cortical bone thicknesses and densities of the jaw bones significantly increased from the crest to base of alveolar crest.The average cortical bone thicknesses rangedfrom 1.0 to 1.5 mm in the anterior part of the jaw bones,1.1 to 1.8 mm in maxillary posterior area and 1.5 to 2.8 mm in the mandible posterior areas.The cortical bone thickness and density were greater in the mandible than in the maxilla(P ＜ 0.05).The thickness values did not show difference between males and females,between adolescents and adults.Higher values of bone density were found in the adults than in the teenagers(P ＜0.05).The highest bone density in the mandible posterior area of adults was observed,and the lowest bone density in the maxillary posterior area of adolescents.Conclusion:Alveolar cortical bone density of adolescents is lower than that of adults,especially in the maxilla posterior region.