BACKGROUND: Streptococcus mutans (S. mutans) is generally considered to be the principal aetiological agent for dental caries, thrS gene may relate to the virulence of S. mutans involved in the adherence, acidogenicity and acidodurance.OBJECTIVE: To investigate the conservation status of the thrS gene of S. mutans and to construct the homologous recombinant plasmid.METHODS: Southern Blot was used to analyze the distdbuUon of thrS gene in S. mutans. The upstream and downstream sequences of thrS gene were cloned respectively into multiple cloning sites of suicide plasmid pFW5 to construct the recombinant plasmid,RESULTS AND CONCLUSION: The thrS gene was conserved in 6 strains of S. mutans in this test. By PCR analysis and enzyme digesting, it was confirmed that S. mutans thrS gene homologous recombinant plasmid was successfully constructed,which can be used in future research of construction of thrS -negative mutans of S. mutans strain UA159.

Objective To compare the effects of Dan Shen Extract F(DSEF) and cimetidine (CI) on reperfusion injury in gastric antrum. Methods Nineteen Wistar rats were randomly allocated to receiving intravenously normal saline (group NS, n = 7), DSEF 1g/100g wt (group DSEF, n = 6) or CI 6.5mg/ 100g wt (group CI, n = 6 ) respectively. Model of hemorrhagic shock roperfusion injury was produced by Itch method. The index and depth of gastric mucosal lesion, prostaglandins content and intracellular calcium content of gastric antrum mucosa were measured. Results (1 ) As compared with those in group NS, the index and depth of gastric mucosal lesion (grade 2, 3) decreased significantly in group DSEF and CI (P 0.05 ). (3 ) The intracellular calcium content in group DSEF and CI was markedly lower than that in group NS (P 0. 05). Conclusions Both DSEF and CI can prevent largely the reperfusion injury in gastric antrum mucosa through different mechanisms, with DSEF having stronger potency.

Objective To investigate the correlation between non-lacunar infarcts in the white matter of brain and intracranial or extracranial vessels stenosis.Methods Brain magnetic resonance imaging(MRI) and digital subtraction angiography(DSA) were performed in 30 patients with non-lacunar infarcts in the white matter of brain and the results were analyzed.Results Of 12 cases with focal non-lacunar infarcts in the area of basal ganglion,9 cases were shown occlusion or highly stenosis of proximal segments of unilateral internal carotid artery(ICA) in DSA,2 cases were shown highly stenosis of M1 segment of middle cerebral artery(MCA),and 1 case was normal.Of 6 cases with focal non-lacunar infarcts in the area of basal ganglion and lateral periventricular white matter,3 cases were shown occlusion or highly stenosis of proximal segments of unilateral ICA in DSA,1 case was shown occlusion of C5 segment of unilateral ICA,and 2 cases were shown occlusion of M1 segments of MCA.Of 4 cases with focal non-lacunar infarcts in periventricular white matter or centrum ovale,1 case was shown occlusion of C5 segment of unilateral ICA,2 cases were shown highly stenosis of M1 segments of MCA,and the other one was normal.Of 8 cases with subcortical superior border infarction(SSBI) or subcortical lateral border infarction(SLBI),6 cases were shown occlusion or highly stenosis of proximal segments of unilateral ICA,1 case was shown occlusion of proximal segments of bilateral ICA,and 1 case was shown occlusion of M1 segment of MCA.Conclusion There are strong correlations between focal non-lacunar infarcts in the areas of basal ganglion or lateral periventricular white matter and the stenosis or occlusion of large arteries of ICA system.

Objective:To knock the phospho-sugar mutase gene (psm) out of the genome of S. mutans strain UA159 and to construct the mutant will lay a foundation for the study of the function of the psm. Methods:Two upstream and downstream DNA sequences of the psm were selected and cloned respectively into multiple cloning sites I and II of suicide plasmid pFW5 to construct the recombinant plasmid which was confirmed by enzyme digesting and sequencing. The recombinant plasmid was transformed into S. mutans UA159 by natural transformation and antibiotic was used to screen the positive transformants. According to the principle of homologous recombination, allelic exchange between the recombinant plasmid and S. mutans UA159 was achieved. Results:By PCR analysis and sequencing, it was confirmed that the psm of S. mutans UA159 was substituted for resistant gene of spectinomycin. Conclusion: The psm-negative mutants of S. mutans UA159 is successfully constructed.

Objective To observe the therapeutic effect of resveratrol (Rsv) on psoriasis like skin damage induced by imiquimod (IMQ) and study its mechanism.Methods BALB/c mice were randomly divided into four groups:control group,Rsv group,model (IMQ) group and Rsv treatment (IMQ + Rsv) group with six mice in each group.Psoriasis like skin model induced by smearing IMQ in the mice's ear for 8 d,20 mg Rsv cream were gave at the same time for treatment.Observe erythema and psoriasis degree,and measure ear thickness with vemier caliper.HE staining was used to observe tissue change,real time quantitative PCR (qRT-PCR) was used to detect K17,IL-17A,IL-19 and IL-23 mRNA and Western blotting were used to detected K17 protein expression in tissues.Results Compared with the model group,mice erythema area and the thickness of epidermal scale decreased significantly in Rsv treatment group;HE staining results showed that,Rsv significantly reduced ear marginal tissue epidermal thickness,and diminished severity of the psoriasis-like skin inflammation.qRT-PCR and Western blotting confirmed a Rsv dependent decrease of in K17,IL-17A and IL-19 in mRNA level and protein levels of K17.Conclusion Rsv improves psoriasis like skin damage by down-regulating expression of Keratinl 7.

Objective To study the influence of the preparation and quality control of Xiaochuan cataplasm on its drug action. Methods Xiaochuan cataplasm was prepared with hydrosoluble polymers matrix. A sequence of tests such as adhesive force test, recontour test, paste-content test, cold-resistance test, heat-resistance test, toxicity and pharmacodynamic action tests were performed on this drug. Results Xiaochuan cataplasm contains a sound volume of medicine, and shows good adhesive property, no sensibilization and stimulation, and notable drug action. Conclusion The results demonstrate that the preparation craft of Xiao-chuan cataplasm is reasonable and practicable., the quality is controllable and the method is a safe and effective transdermal drug delivery system.

Objective:To explore the relationship among childhood psychological maltreatment,online aggressivebehavior and trait anger in college students.Methods:Totally 442 college students (226males,216 females,aged 16-25 years) were surveyed with the Psychological Maltreatment Scale (PMS),Adolescent Online Aggressive Behavior Scale (AOABS) and Trait Anger Scale (TAS).The bias-corrected percentile bootstrap method was used to analyze the mediating effect of trait anger between childhood psychological maltreatment and online aggressive behavior.Results:The scores of PMS,AOABS and TAS were positively correlated each other(r =0.44,0.37,0.48,Ps ＜0.01).The PMS scores had a significantly direct effect on the AOABS scores,its estimate was 0.27.The PMS scoreshad a significantly indirect effect on the AOABS scores through TAS scores(95％ CI:0.15-0.34).Conclusion:It suggests that the trait anger may be related to childhood psychological maltreatment and online aggressive behavior,and trait anger may play a partial mediating role between childhood psychological maltreatment and online aggressive behaviorin college students.

Objective To study AngⅡ induced apoptosis of HUVECs and to observe the protective effect of serum contained huangqi on endothelial cell.Methods ECV-304 cells were randomly divided into control group,AngⅡgroup and huangqi group.In the control group,cells were cultured for 18 h,and the concentration of AngⅡ were 0 mol/L,1×10-6 mol/L,1×10-5 mol/L and 1×10-4 mol/L.The cell proliferation was measured by MTT assay.Electron microscope was used to observe the change of HU-VECs.Ultrastructure of HUVECs induced by AngⅡ was observed by electron microscope.In the huangqi group,serum contained huangqi of different concentration were added into the medium and cultured for 24 h,then AngⅡ of 1×10-4 mol/L was included and cultured for 18 h,and the apoptosis ratio induced by AngⅡwas measured by flow cytometry.Results AngⅡof different con-centration could all significantly inhibit HUVECs proliferation.AngⅡof different concentration could all induce endothelial cell ap-optosis.HUVECs apoptosis was observed by electron microscope.HUVECs apoptosis induced by AngⅡcould be inhibited by ser-um contained huangqi.Conclusion Serum contained huangqi could protect endothelial cells.

Objective To determine the level of peripheral blood CD34 positive (CD34+) cells in patients with acute cerebral infarction (ACI),and to explore its clinical significance.Methods The level of peripheral blood CD34+ cells was determined by flow cytometry within 72 hours of onset of patients with acute cerebral infarction (infarct group,n=45),cerebrovascular risk factors in patients without cerebral infarction (high risk group,n=27) and healthy subjects (control group,n=20).The neural function defect score,infarction lesion volume and carotid artery intima-media thickness (IMT) were determined in patients with infarction group.Results The percentages of peripheral blood CD34 cells in infarction group (0.034 ±0.012)％ and the high risk group of patients (0.047±0.009)％ were lower than that of control group(0.063±0.009)％,and were lower in infarction group than in high-risk groups (all P＜0.05).The percentages of peripheral blood CD34+cells were significantly decreased compared with control group (P＜0.05) in infarction patients with mild [(0.047±0.009)％],moderate [(0.036±0.009)％],severe [(0.022±0.007)％] infarction nervous function defect score.Wherein,the percentages were lower in severe group than in the moderate group,moderate group was lower than in mild group (all P＜0.05).The percentages of peripheral blood CD34 cells in infarction patients with small,moderate,large infaret lesion volume were lower than in control group (P＜0.05),wherein,were lower in large group than in moderate group,lower in moderate group than in treatment group (all P＜0.05).Infarction patients were confirmed with carotid atherosclerosis (CAS) by carotid ultrasound.The extent of lesion were divided into carotid artery intimal thickening group [(0.043±0.010)％],carotid artery plaque group [(0.036±0.010)％],and carotid artery stenosis group [(0.023±0.009)％].The levels of peripheral blood CD34+ cells in three groups of patients were decreased compared with control group.The levels were lower in carotid artery stenosis group than in carotid artery plaque group,lower in carotid artery plaque group than in carotid artery intimal thickening group (all P＜0.05).Conclusions The level of peripheral blood CD34+ cells in acute cerebral ischemia is reduced,it can become a sensitive and early indicator of cerebral ischemia,and its level is related to neurologic impairment,infarction size and the degree of carotid artery atherosclerosis.

In this paper,the educational mode of master of public health (MPH) in America and China were reviewed through literatures searching and internet searching and the difference between America and China were compared from the sources of students,students' characters,educational objective,specialties and curricula,methods of teaching and management.There is still a certain gap in education of MPH in China.The educational mode needs optimizing with changing enrollment methods,definitude training objectives,perfect curriculum setting,increased opportunities for practice and strict quality control,so that the educational mode of MPH will be perfected in China.