BACKGROUND: Critical incidents are natural and man-made disasters arising suddenly, which are beyond the ability of the individuals to resist or control. In the situation of stress, individuals feel stuck, and are unable to control the situation.OBJECTIVE: To confirm the assessment model of stress response to critical events and the interventional effect of social support, general self-efficacy and coping efficacy.DESIGN: A randomized sampling, questionnaire-based investigation.PARTICIPANTS: We selected 1016 college students of 17 provinces or cities including Beijing, Guangzhou, Hefei, Jilin, Jiangsu, Jiangxi , Liaoning, Sichuan, Inner Mongolia, Shandong , Shanghai, Hebei, Tianjin,Wuhan, Zhejiang , Chongqing and so on as subjects. Totally 708 college students selected from the above regions received the same survey one year later.METHODS: Depression and anxiety state of the subjects were investigated with Center for Epidemiological Studies Depression Scale (CESD)and Anxiety Inventory (SAS) during SARS. Social support condition was investigated with Social Support Rating Scale, authorized by Xiao Shuiyuan. Related items were amended considering used among college students. The subscale was integrated into 3 subscales including group-support, friend-support and social support utilization. One year later, stress response to SARS was investigated again with self-made coping efficacy scale, self-esteem scale and self-efficacy scale and SARS Stress Response Questionnaire, which included 13 items measuring the students in three aspects: cognitive evaluation to SARS epidemic, such as "I believe human beings can conquer SARS in the end"; panic to SARS, like "worrying about SARS sweats me and makes me feel shiver sometimes"; and defense response to SARS, as "In order to prevent SARS, I have to wear respirator in the public". As far as cognitive, panic emotion and defense behaviors were concerned. The coping efficacy developed by the author covered 18items, such as "I'm afraid that I can not deal with things", "I have enough confidence to conquer any difficulty", and namely as friability, confidence and intelligence.RESULTS: ① The two investigated results were compared through assessment of covariation. There was a significant difference in cognitive condition, panic emotion and defense behavior; that was to say, the stress response to SARS had been obviously relieved . ② Social support and SARS stress response model x2=8.654,df=4,P=0.07;criterion fit index NFI= 1, RFI =0.997 and IFI =1, RMSEA=0.034. ③self-efficacy confirmative factor analysis showed the following: x2=0.536,df=2,P=0.765;x2/df=0.268, NFI=1, RFI=1, IFI=1 and CFI=1, RMSEA=0.000. ④The discriminating and convergent validity of coping efficacy questionnaire was as follows. The coefficient was 0.633 with general efficacy questionnaire, 0.530 with self-respect (SES), 0.481 with CESD, 0.387 with anxiety (SAS), and -0.003 with living events. ⑤ A structural equation model about general self-efficacy, coping efficacy and SARS stress response was established: x2 =2.722 df=3, P=0.437; NFI=1, RFI=0.999,IFI=1, CFI=1, RMSEA=0.068. The model fitted well. According to the data, coping efficacy affected SARS stress response negatively (the coefficient was -0.59)CONCLUSION: ① The three-dimensional assessment model assessed the stress response to critical incidents including cognitive adjustment, emotional response and behavioral tendency. The three-dimensional model stood the test while assessing SARS stress response. Compared with the assessment of emotional disorders, such as depression and anxiety, the model was more sensitive. ②Social support played a vital role in the stress response to critical incidents as a buffer or a regulator. It showed more influence on emotional disorders than on SARS stress response. ③Coping efficacy was a measurable intervening variable, which deserves more attention to in the stress response to critical incidents. Compared with general self-efficacy, coping efficacy had a greater intervening effect on SARS stress response.

Objective:To investigate the patterns of microbial infection on the apical external root surfaces of treated and untreated teeth associated with chronic apical periodontitis and to study bacteria in the biofilm in order to find out the species,constitution and origination of bacteria in periapical biofilm.Methods: Ten teeth with chronic apical periodontitis from patients of the Department of Stomatology of People's Hospital,Peking University: 5 untreated teeth with a radiographically visible chronic periradi-cular lesions and 5 teeth with extensive carious lesions,radiolucent lesions of varying sizes and attached periradicular tissues were selected for study.Using aseptic techniques and sterile instruments,bacterial samples of the root canals were taken,inoculated and separated according to usual practice.After extraction,ten teeth were fixed and the apical 5 mm portion of one root was sectioned.Root tips were dehydrated,sputter coated with gold,and then examined for the occurrence of bacteria on the apical root surfaces using scanning electron microscope.Five healthy teeth with vital pulp were used as controls.Results: Microbial study showed that ten specimens yielded bacterial growth.The most prevalent bacteria were P.micros and F.nueleatum.In the 5 untreated teeth,bacterial cells were usually observed close to the apical foramen in only 1 specimen.Morphologically,these bacteria consisted of cocci.In the 5 treated teeth,a dense bacterial aggregation composed mainly of cocci and rods was observed surrounding the apical foramen of all specimens.Besides rods,other bacterial morphological types were recognized,including coaggregations of cocci and filaments,characterizing a fully developed "corn-cob".No microorga-nisms were found in the healthy controls.Conclusion:Bacterial biofilm was always present in teeth with post-treatment endodontic disease.The presence of apical bacterial biofilm is clinically important,and it may cause failure of endodontic treatment as a consequence of persistent infection.

Objective:To establish an in vitro root canal model infected by Enterococcus faecalis and to observe the morphology,distribution and relative position of Enterococcus faecalis in infected root canals.Methods: Ten human healthy premolars extracted for orthodontic reasons were collected.Following sterilization,a total of 5 specimens were aseptically transferred to separate Eppendorf tubes containing 1.5 mL brain-heart infusion broth(BHI) inoculated with 0.1 mL Enterococcus faecalis suspension that had been adjusted to Mcfarland 5,and were incubated at 37 ℃ for 21 days.The other 5 specimens were as controls.The roots of all specimens were then split into two halves along the mesiodistal axis.One half was processed with light microscopic(Brown & Brenn stain) to check the bacteria in dentinal tubules,and the other was observed with SEM to investigate the bacterial status in infected root canals.Results: Enterococcus faecalis could penetrate into the dentinal tubules about 330-1 000 ?m.A dense bacterial aggregation composed of Enterococcus faecalis and amorphous matrix was observed in the apical third of the root canals,whereas Enterococcus faecalis were seen free-floating or planktonic in the crown and middle third of the root canals.No microorganisms were found in the root canals of the controls.Conclusion: Enterococcus faecalis could form bacterial biofilm on the root canal walls and penetrate into the dentinal tubules.The in vitro model designed was simple,and had good practicability to make a further comparative evaluation of various antimicrobial methods in the reduction of intracanal bacteria.

Obiective To detect the carotid-femoral pulse wave veloeity(CF-PWV) and evaluate relation in pulse pressure (PP) and pulse wave velocity ('PWV), and prove the effect of dynamic error analysis system on pulse wave velocity measure. Methods 486 cases with essential hypertension were detected with carotid-femoral pulse wave velocity. The dynamic error was controlled in three kinds of condition: 15%>error>10%, 10%>error>5% and 5%>error, which PWV values were tested repeatedly with the effect of different errors observed. At the same time the blood pressure was measured and the pulse pressure was calculated. Results The pulse wave velocity which pulse pressure ≥60mm Hg (1mm Hg=0.133 kPa) was significantly higher than pulse pressure <60turn Hg [(14.2± 2.34)m/s and (8.5±1.81)m/s, P<0.001] . Pulse wave velocity and pulse pressure and age showed a significant positive correlation (pulse pressure r=0.529, P=0.000; age r= 0.331 P=0.003).When dynamic error is more than 10% and less than 15%, the diversity of PWV values showed the significance of statistics. Conclusion The effect of dynamic error analysis system on pulse wave velocity measure, less error test pattern is advantageous to enhance accuracy. The pulse pressure is closely related to pulse wave velocity. Arterial pulse wave velocity is a new evaluation of the indicators of arterial stiffness, and it's more scientific, accurate and eonvenient.

Objective To investigate the association of prehepatic fat thickness with insulin resistance in women with polycystic ovarian syndrome (PCOS).Methods Thirty-five PCOS patients and 39 controls were randomly enrolled in the study.Prehepatic fat thickness was detected by ultrasound,and fasting glucose (FBG),fasting insulin (FINS),and serum lipids were detected.The homeostasis model assessment of insulin resistance (HOMA-IR) was used to calculate insulin resistance.Results Prehepatic fat thickness was significantly higher in PCOS patients than healthy controls,and prehepatic fat thickness were significantly correlated with HOMA-IR (P ＜ 0.05).The receiver operating characteristic (ROC) curve demonstrated that prehepatic fat thickness had higher sensitivity and specificity in diagnosing PCOS with insulin resistance.Conclusions This study demonstrates that prehepatic fat thickness significantly correlates with insulin resistance and can be used as the markers of insulin resistance in PCOS patients.

To evaluate the clinical effects of rotary nickel-titanium instruments Mtwo in root canal therapy in the aged patients. Using step-back technique,80 teeth with pulpal and periapical involvement were instrumented by Mtwo in the M group, and by K file in the K group. Mtwo could keep the original curvature and flow of the root canals. No transportation, apical blockage, ledge or perforation was found in the M group. There was more complications in the K group than in the M group.The operative time was shorter and posttreatment pain seldom occurred in the M group. With rotary NiTi instruments Mtwo for seniles' root canals treatment, root canals can be prepared effectively and quickly,and is worth of clinical application.

Objective:To establish an in vitro root canal model infected by Enterococcus faecalis and to observe the morphology, distribution and relative position of Enterococcus faecalis in infected root canals.Methods: Ten human healthy premolars extracted for orthodontic reasons were collected. Following sterilization , a total of 5 specimens were aseptically transferred to separate Eppendorf tubes containing 1. 5 mL brain-heart infusion broth (BHI) inoculated with 0.1 mL Enterococcus faecalis suspension that had been adjusted to Mcfarland 5, and were incubated at 37℃ for 21 days. The other 5 specimens were as controls. The roots of all specimens were then split into two halves along the mesiodistal axis. One half was processed with light microscopic ( Brown & Brenn stain) to check the bacteria in dentinal tubules, and the other was observed with SEM to investigate the bacterial status in infected root canals. Results: Enterococcus faecalis could penetrate into the dentinal tubules about 330-1 000μm. A dense bacterial aggregation composed of Enterococcus faecalis and amorphous matrix was observed in the apical third of the root canals, whereas Enterococcus faecalis were seen free-floating or planktonic in the crown and middle third of the root canals . No microorganisms were found in the root canals of the controls. Conclusion:Enterococcus faecalis could form bacterial biofilm on the root canal walls and penetrate into the dentinal tubules. The in vitro model designed was simple, and had good practicability to make a further comparative evaluation of various antimicrobial methods in the reduction of intracanal bacteria.

In recent years,the incidence of hepatocellular carcinoma (HCC) has increased with a higher mortality rate.Early detection and early treatment are essential to improving the patients' survival rate. Imaging is widely used HCC and is advantageous because it is non-invasive. The rapid development of imaging calls for higher standards in order to diagnosis hepatocarcinoma at an earlier stage so as to achieve complete treatment.This review describes the scientific progress on imaging differential diagnosis and application on pre-cancerous nodules (dysplastic nodule,DN) and small hepatocellular carcinoma (sHCC) related to hepatocarcinogenesis in cirrhotic livers.

Malignant tumor is a serious threat to human health and its pathogenesis is complex , which caused by interaction of a variety of carcinogenic factors in the human body .SALL4 gene is a kind of newly dis-covered gene and it plays an important role in function of embryonic stem cell due to its protein transcription fac -tor with C2H2 zinc finger domain.Studies found that this gene mutation often results in occurrence of malignant tumor.This paper will summarize the molecular mechanism of SALL 4 in the occurrence and development of malig-nant tumor and its diagnosis and treatment on malignant tumor .

Dibutyl phthalate (DBP) has been found as a ubiquitous environmental pollutant with reproductive and developmental toxicity. The characteristics of reproductive and developmental toxicity of DBP, the mechanisms of the toxicity and effects on human health were reviewed in this paper according to the toxic effects on pregnant animals exposed to DBP, which might provide reference for the further study on toxicity of DBP and preventive measures.