The evaluation system of PBL teaching was constructed to develop PBL teaching in combination with the characteristics of medical courses. It covered students evaluation system, teacher's evaluation, and teaching pattern system in all aspects of teaching. The present study was carried out through repeated verification in many clinical medicine curriculum and many grades of students, and standardized assessment model, a more mature evaluation system, has been fully applied. All the indices of the evaluation system were comprehensive in contents, scientific, objective, manipulated easily and with good results, which is worth promoting the application of PBL teaching in the future.

In order to provide morphological data and theoretical basis for pig-to-human hepatic xenotransplantation, the difference in morphological parameters and vessel wall structural factors between human and porcine hepatic portal vein was studied. From human subjects and pigs of varying ages, hepatic portal veins were collected, paraffin-embedded and cut into sections. The histological structures were stained with HE, and elastin, collagen and smooth muscles were stained with Weigert, Aniline blue and orange G, respectively. Morphological parameters and relative contents of structural components were determined under microscopy and by computer image analysis system, respectively. The results showed that histological structures of human and porcine hepatic portal vein wall were similar. Caliber, wall thickness, lumen and wall area in pigs increased with age, all in linear correlation to months. Morphological parameters of 6- month-old pigs were similar to those of human. In pigs, collagen content increased gradually with months, elastin content remained relatively stable, smooth muscle content reached the peak at the 3rd month, and collagen/elastin (C/E) rose gradually. The contents of collagen and elastin in porcine hepatic portal vein wall were lower, while the content of smooth muscle was higher than in human, and C/E at the 5th and 6th month was similar to that in human. It is concluded that morphological parameters and contents of structural components of porcine hepatic portal vein vary with age. At the 6 month, its caliber, wall thickness, lumen and wall area are similar to those of human. There are differences in contents of structural components between human and pigs. However, in terms of C/E, mechanic properties of pigs at the 5th and 6th month mimic those of human, hence inosculation is viable in xenotrans-plantation between pigs and human.
Collagen/*analysis ; Elastin/*analysis ; Image Processing, Computer-Assisted ; Liver Transplantation ; Muscle, Smooth, Vascular/cytology ; Portal Vein/*anatomy & histology ; Portal Vein/chemistry ; Swine ; Transplantation, Heterologous

BACKGROUND: Due to the source of conspecific heart transplanted organ is limited and it becomes more and more deficient, and porcine cardiovascular system and haemodynamics are very similar to that of human being, therefore, domestic and foreign scholars have paid more attention on the heterogeneic heart transplantation from swine to human, and there are more and more basic studies about it.OBJECTIVE: To compare the zero-stress state of ascending aorta and pulmonary artery trunk between swine of different months and healthy persons, which provides necessary vascular tissue reconstruction basis for anastomosing vessel of heterogeneic heart transplantation from swine to human being.DESIGN: Open experiment.SETTING: Laboratory of Biomechanics, Yunyang Medical College.MATERIALS: This experiment was carried out at the Laboratory of Biomechanics, Yunyang Medical College from October 2001 to September 2002. Human heart specimens were chosen from 6 male adult corpses who had no visible manifestation of cardiovascular diseases, aged 18 to 30 years. Informed consents were obtained from all the relatives. Totally 42 conspecific swine, aged one month, were also chosen and divided into 7 groups, named as 1,2,3,4,5,6 and ＞ 6 months groups respectively, with 6 in each group. Swine were anesthetized at 1,2,3,4,5,6,＞ 6 months respectively and sacrificed in each group.METHODS: The corresponding ascending aorta and pulmonary artery trunk were dissected and isolated. Each arterial anterior wall was labeled in situ with coloring pen, and then artery was shifted into the oxygen-saturated Kreb's solution. Five isometric vascular rings were divided along the axial direction, then each vascular ring was cut open along the radial direction. Opening angle of each vascular ring at zerostress state was measured and recorded by computer 20 minutes later(The included angel formed through connecting the middle point of inner wall of open vascular plane and two end points of inner wall). The experiment was conducted at room temperature 20-30 ℃. All the procedures of vascular samples were performed within 24 hours after subjects died.MAIN OUTCOME MEASURES: Measuring results of opening angle of ascending aorta and pulmonary trunk at zero-stress state of swine at different months and human being.RESULTS: ①Comparison of measuring results of opening angle of ascending aorta and pulmonary trunk between swine at different months and human being: Opening angle of ascending aorta of human being increased from (100.4±12.8)°at proximal end to (152.8±18.6)°at distal end. Opening angle of swine at different months increased from about 68°at proximal end to about 130°at distal end; Opening angel of pulmonary artery trunk of human being did not changed significantly along axial direction, and opening angel of pulmonary artery trunk of swine at different months increased from about 65° at proximal end to about 125°at distal end. There was significant difference of opening angle of ascending aorta and pulmonary trunk at zero-stress state between human being and swine (P=0.028 ＜ 0.05).But the opening angle of ascending aorta of human being was similar at the second segment to at the fourth and fifth segments of swine of different ages; Opening angle of each segment of pulmonary artery trunk of human being was close to that of proximal end (first and second segments) ofpulmonary artery trunk of swine.② Comparison of measuring results of ascending aorta and pulmonary artery trunk at zero-stress state of swine at different months: Opening angle of ascending aorta and pulmonary artery trunk of swine did not changed with the increase of age (P=-0.063 ＞ 0.05).CONCLUSION: Opening angels of ascending aorta and pulmonary artery trunk at zero-stress state are close in some segments between human being and swine, suggesting that corresponding ascending aorta or pulmonary artery trunk can mutually anastomose in some segments in the heterogeneic heart transplantation from swine to human, and the effect of age is not significant in vascular reconstruction.

BACKGROUND:The self-ligating bracket is superior to the conventional bracket in orthodontic treatment, but there are a lot of controversies. At present, researchers have different views on the function of self-ligating brackets. OBJECTIVE:To summarize the comparative study of self-ligating brackets and conventional brackest with the direction and development in recent years. METHODS:A computer-based search of PubMed (2000-2014) and CNKI (2000-2014) databases was done for relevant articles, using the key words of “self-ligating brackets; conventional orthodontic brackets” in English and Chinese, respectively. RESULTS AND CONCLUSION:Self-locking brackets saves chair side time, which has been confirmed and accepted. There are different views for the issue that self-ligating brackets can reduce friction in orthodontic treatment. It is widely accepted that, the self-ligating brackets using thin round wire had less friction than the conventional brackets; whether the friction of self-ligating brackets in the closed gap and fineness adjustment stages is less than the conventional brackets stil remains unclear, which need further clinical comparative studies. The self-ligating brackets showed no significant difference with the conventional brackets in arch expansion, reducing anchorage loss and root adsorption. The majority of relevant studies is performedin vitro, and cannot exactly simulate the dental conditions. A large-size experiment with the uniform criteria for therapeutic efficacy is needed to objectively evaluate self-ligating brackets.

BACKGROUND:Buccal Multiloop Removable Appliance can interceptively correct mutiple adolescent malocclusions. But the clinical problem of Buccal Multiloop fatigue fracture is not solved yet. How to prolong the fatigue fracture cycle is stil in the research stage. OBJECTIVE: To study the effect of different temperature of heat treatment on the Buccal Multiloop fatigue fracture cycle, thereby to select a relatively optimal method to enhance the fatigue fracture cycle. METHODS: Thirty-five left HL-2 Buccal Mltiloops were divided into seven groups according to different ways of heat treatment. Each group consisted of five samples. They were an untreated group, three pre-bending groups (320, 420, 520℃ heat treatment before bending) and three post-bending groups (320, 420, 520℃ heat treatment after bending). The dental stainless steel wires and Buccal Multiloop were respectively treated by low-temperature annealing. The data were recorded and evaluated after the samples tested by the 3D Simulating Movement of TMJ Testing Machine. The features of fatigue fracture were observed by scanning electron microscope. RESULTS AND CONCLUSION: The mean values of the Buccal Multiloop fatigue fracture cycle from largest to smalest were as folows: 520℃ pre-bending group > 420℃ pre-bending group > 320℃ pre-bending group > untreated group > 520℃ post-bending group > 320℃ post-bending group > 420℃ post-bending group. The fatigue fracture cycle of Buccal Multiloop made of the dental stainless steel wires after 520℃ annealing treatment was longer than others. By the observation of scanning electron microscope, the fracture crack extension area had the tendency to expand, transient interruption was delayed and the tissue structure became more uniform.

ObjectiveTo observe the effect of ultrashort waves combined with medication on children with cerebral dysfunction syndrome (CDS) accompanied with pneumonia.Methods76 children with CDS accompanied with pneumonia were randomly divided into treatment group (n=38, treated with anti-inflammatory and ultrashort waves one time per day for ten days) and control group (n=38, treated only with anti-inflammatory). The effective rate and the days of rales vanished of children in two groups after treatment were compared.ResultsIn the treatment group, 14 cases cured, 20 cases got significant result, 4 cases were effective, total effective rate was 100%; in the control group, 10 cases cured, 14 cases got significant result, 9 cases were effective, 5 cases were invalid, total effective rate was 86.8%. There was a significant difference between therapeutic effects of two groups ( P<0.05).ConclusionThe ultrashort waves therapy is an effective method for the children with CDS accompanied with pneumonia.

Objective To investigate the pathological changes and mechanism in the urethra by parturition-induced stress urinary incontinence.Methods Sprague Dawley female rats underwent vaginal balloon dilation for 4 hours immediately after delivery.One week later,the rats were anesthetized and both ovaries were excised.Then a rat model of stress urinary incontinence (SUI) was successfully established.One month after ovariectomy,conscious cystometry and Leak-Point Pressure (LPP) were measured by MP150.Histological examination and Western blotting were performed after functional assays.Results (1) 85％ of rats presented astress urinary incontinence in the model group.(2) The urethras in SUI rats had decreased muscles,and striated muscles showed fragmentized and disorganized.(3) Elastic fibers were long,well organized and tightly connected to the muscle bundles in sham group,while elastic fibers showed fragmentation and disorganization in the model group.(4) The protein expression of vascular endothelial growth factor (VEGF) and blood vessels were reduced in SUI rats as compared with the sham rats.Conclusions Muscle and elastic fibers in the urethra are disrupted in SUI rat.VEGF may play an important role in regulation of pathological changes in urethra.

In order to provide morphological data and theoretical basis for pig-to-human hepatic xenotransplantation, the difference in morphological parameters and vessel wall structural factors between human and porcine hepatic portal vein was studied. From human subjects and pigs of varying ages, hepatic portal veins were collected, paraffin-embedded and cut into sections. The histological structures were stained with HE, and elastin, collagen and smooth muscles were stained with Weigert, Aniline blue and orange G, respectively. Morphological parameters and relative contents of structural components were determined under microscopy and by computer image analysis system, respectively. The results showed that histological structures of human and porcine hepatic portal vein wall were similar. Caliber, wall thickness, lumen and wall area in pigs increased with age, all in linear correlation to months. Morphological parameters of 6- month-old pigs were similar to those of human. In pigs, collagen content increased gradually with months, elastin content remained relatively stable, smooth muscle content reached the peak at the 3rd month, and collagen/elastin (C/E) rose gradually. The contents of collagen and elastin in porcine hepatic portal vein wall were lower, while the content of smooth muscle was higher than in human, and C/E at the 5th and 6th month was similar to that in human. It is concluded that morphological parameters and contents of structural components of porcine hepatic portal vein vary with age. At the 6 month, its caliber, wall thickness, lumen and wall area are similar to those of human. There are differences in contents of structural components between human and pigs. However, in terms of C/E, mechanic properties of pigs at the 5th and 6th month mimic those of human, hence inosculation is viable in xenotransplantation between pigs and human.

The database with standard 3D tooth crowns has laid the groundwork for dental CAD/CAM system. In this paper, we design the standard tooth crowns in 3DS MAX 9.0 and create a database with these models successfully. Firstly, some key lines are collected from standard tooth pictures. Then we use 3DS MAX 9.0 to design the digital tooth model based on these lines. During the design process, it is important to refer to the standard plaster tooth model. After some tests, the standard tooth models designed with this method are accurate and adaptable; furthermore, it is very easy to perform some operations on the models such as deforming and translating. This method provides a new idea to build the database with standard 3D tooth crowns and a basis for dental CAD/CAM system.
Computer-Aided Design ; Databases, Factual ; Dental Models ; Dental Prosthesis Design ; methods ; trends ; Imaging, Three-Dimensional ; Tooth Crown ; anatomy & histology

We have carried out a research on the method for Computer Aided Design and Manufacturing (CAD/ CAM) of the framework of porcelain-fused-to-metal(PFM) fixed bridge. Taking the missing of the mandibular first molar as an example, firstly, we used ATOS II 3D scanner to collect the 3D data of the abutment teeth and used the acquried data to design the coping crowns. Secondly, the relevant standard bridge was selected from the standard bridges database and was deformed inaccordance to the characteristic of the patient. Then it was set to the correct position between the coping crowns automatically based on the restricting lines and faces. Finally, the connector was designed to connect the coping crowns and the bridge based on the touching area. The final product was manufactured by 3-axis NC milling machine. The results of examination showed that the framework of PFM fixed bridge fitted the abutment teeth very well, and the hardness of the connector and the precision of the whole model were feasible and reasonable. The method of designing and manufacturing the framework of PFM fixed bridge from CAD/CAM is practicable, efficient and accurate. It is also an important part of homemade dental CAD/CAM system.
Computer-Aided Design ; Crowns ; Dental Abutments ; Dental Prosthesis Design ; methods ; Denture, Partial, Fixed ; Humans ; Metal Ceramic Alloys ; Molar