The value of radiomics based on contrast-enhanced spectral mammography of internal and peripheral regions combined with clinical factors in predicting benign and malignant breast lesions of breast imaging reporting and data system category 4 / 中华放射学杂志

Objective:To evaluate the value of radiomics based on contrast-enhanced spectral mammography (CESM) of internal and peripheral regions combined with clinical factors in predicting benign and malignant breast lesions of breast imaging reporting and data system category 4 (BI-RADS 4).Methods:A retrospective analysis was performed on the clinical and imaging data of patients with breast lesions who were treated in Yantai Yuhuangding Hospital (Center 1) Affiliated to Qingdao University from July 2017 to July 2020 and in Fudan University Cancer Hospital (Center 2) from June 2019 to July 2020. Center 1 included 835 patients, all female, aged 17-80 (49±12) years, divided into training set (667 cases) and test set (168 cases) according to the "train-test-split" function in Python software at a ratio of 8∶2; and 49 patients were included from Center 2 as external validation set, all female, aged 34-70 (51±8) years. The radiomics features were extracted from the intralesional region (ITR), the perilesional regions of 5, 10 mm (PTR 5 mm, PTR10 mm) and the intra-and perilesional regions of 5, 10 mm (IPTR 5 mm, IPTR 10 mm) and were selected by variance filtering, SelectKBest algorithm, and least absolute shrinkage and selection operator. Then five radiomics signatures were constructed including ITR signature, PTR 5 mm signature, PTR 10 mm signature, IPTR 5 mm signature, IPTR 10 mm signature. In the training set, univariable and multivariable logistic regressions were used to construct nomograms by selecting radiomics signatures and clinical factors with significant difference between benign and malignant BI-RADS type 4 breast lesions. The efficacy of nomogram in predicting benign and malignant BI-RADS 4 breast lesions was evaluated by the receiver operating characteristic curve and area under the curve (AUC). Decision curve and calibration curve were used to evaluate the net benefit and calibration capability of the nomogram.Results:The nomogram included ITR signature, PTR 5 mm signature, PTR 10 mm signature, IPTR 5 mm signature, age, and BI-RADS category 4 subclassification for differentiating malignant and benign BI-RADS category 4 breast lesions and obtained AUCs of 0.94, 0.92, and 0.95 in the training set, test set, and external validation set, respectively. The calibration curve showed good agreement between the predicted probabilities and actual results and the decision curve indicated a good net benefit of the nomogram for predicting malignant BI-RADS 4 lesions in the training set, test set, and external validation set.Conclusion:The nomogram constructed from the radiomics features of the internal and surrounding regions of CESM breast lesions combined with clinical factors is attributed to differentiate benign from malignant BI-RADS category 4 breast lesions.

Transmission Dynamics of Coronavirus Disease 2019 (COVID-19) in the World: The Roles of Intervention and Seasonality

The coronavirus disease 2019 (COVID-19) is spreading rapidly all over the world. The transmission dynamics of the COVID-19 pandemic is still unclear, but developing strategies for mitigating the severity of the pandemic is yet a top priority for global public health. In this study, we developed a novel compartmental model, SEIR-CV(susceptible-exposed-infectious-removed with control variables), which not only considers the key characteristics of asymptomatic infection and the effects of seasonal variations, but also incorporates different control measures for multiple transmission routes, so as to accurately predict and effectively control the spread of COVID-19. Based on SEIR-CV, we predicted the COVID-19 epidemic situation in China out of Hubei province and proposed corresponding control strategies. The results showed that the prediction results are highly consistent with the outbreak surveillance data, which proved that the proposed control strategies have achieved sound consequent in the actual epidemic control. Subsequently, we have conducted a rolling prediction for the United States, Brazil, India, five European countries (the United Kingdom, Italy, Spain, Germany, and France), southern hemisphere, northern hemisphere, and the world out of China. The results indicate that control measures and seasonal variations have a great impact on the progress of the COVID-19 pandemic. Our prediction results show that the COVID-19 pandemic is developing more rapidly due to the impact of the cold season in the southern hemisphere countries such as Brazil. While the development of the pandemic should have gradually weakened in the northern hemisphere countries with the arrival of the warm season, instead of still developing rapidly due to the relative loose control measures such as the United States and India. Furthermore, the prediction results illustrate that if keeping the current control measures in the main COVID-19 epidemic countries, the pandemic will not be contained and the situation may eventually turn to group immunization, which would lead to the extremely severe disaster of about 5 billion infections and 300 million deaths globally. However, if Chinas super stringent control measures were implemented from 15 July, 15 August or 15 September 2020, the total infections would be contained about 15 million, 32 million or 370 million respectively, which indicates that the stringent and timely control measures is critical, and the best window period is before September for eventually overcoming COVID-19. SignificanceCOVID-19 is now posing a huge threat to global public health. The key features such as asymptomatic infection and droplet or airborne transmission make COVID-19 more easily spread and more widely distributed around the world. It is an urgent need to explore the optimal intervention strategies and measures to contain the pandemic. Our novel SEIR-CV compartmental model considers the new features of COVID-19, exhibits the impact of the intervention strategies and seasonal variations, and thus can accurately predicts its trajectory in China and the rest of the world. Our research results suggest that control measures and seasonal variations have a great impact on the development of the COVID-19 pandemic, which can only be contained by stringent strategies during the best window period before September 2020 for eventually overcoming COVID-19, otherwise it would cause a severer global catastrophe.

Heparin-induced thrombocytopenia is associated with a high risk of mortality in critical COVID-19 patients receiving heparin-involved treatment

BackgroundCoronavirus infectious disease 2019 (COVID-19) has developed into a global pandemic. It is essential to investigate the clinical characteristics of COVID-19 and uncover potential risk factors for severe disease to reduce the overall mortality rate of COVID-19. MethodsSixty-one critical COVID-19 patients admitted to the intensive care unit (ICU) and 93 severe non-ICU patients at Huoshenshan Hospital (Wuhan, China) were included in this study. Medical records, including demographic, platelet counts, heparin-involved treatments, heparin-induced thrombocytopenia-(HIT) related laboratory tests, and fatal outcomes of COVID-19 patients were analyzed and compared between survivors and nonsurvivors. FindingsSixty-one critical COVID-19 patients treated in ICU included 15 survivors and 46 nonsurvivors. Forty-one percent of them (25/61) had severe thrombocytopenia, with a platelet count (PLT) less than 50x109/L, of whom 76% (19/25) had a platelet decrease of >50% compared to baseline; 96% of these patients (24/25) had a fatal outcome. Among the 46 nonsurvivors, 52{middle dot}2% (24/46) had severe thrombocytopenia, compared to 6{middle dot}7% (1/15) among survivors. Moreover, continuous renal replacement therapy (CRRT) could induce a significant decrease in PLT in 81{middle dot}3% of critical CRRT patients (13/16), resulting in a fatal outcome. In addition, a high level of anti-heparin-PF4 antibodies, a marker of HIT, was observed in most ICU patients. Surprisingly, HIT occurred not only in patients with heparin exposure, such as CRRT, but also in heparin-naive patients, suggesting that spontaneous HIT may occur in COVID-19. InterpretationAnti-heparin-PF4 antibodies are induced in critical COVID-19 patients, resulting in a progressive platelet decrease. Exposure to a high dose of heparin may trigger further severe thrombocytopenia with a fatal outcome. An alternative anticoagulant other than heparin should be used to treat COVID-19 patients in critical condition. FundingThis investigation was supported by grants 2016CB02400 and 2017YFC1201103 from the National Major Research and Development Program of China.

Systemic analysis of tissue cells potentially vulnerable to SARS-CoV-2 infection by the protein-proofed single-cell RNA profiling of ACE2, TMPRSS2 and Furin proteases

Single-cell RNA profiling of ACE2, the SARS-CoV-2 receptor, had proposed multiple tissue cells as the potential targets of SARS-CoV-2, the novel coronavirus causing the COVID-19 pandemic. However, most were not echoed by the patients clinical manifestations, largely due to the lack of protein expression information of ACE2 and co-factors. Here, we incorporated the protein information to analyse the expression of ACE2, together with TMPRSS2 and Furin, two proteases assisting SARS-CoV-2 infection, at single cell level in situ, which we called protein-proofed single-cell RNA (pscRNA) profiling. Systemic analysis across 36 tissues revealed a rank list of candidate cells potentially vulnerable to SARS-CoV-2. The top targets are lung AT2 cells and macrophages, then cardiomyocytes and adrenal gland stromal cells, followed by stromal cells in testis, ovary and thyroid. Whereas, the polarized kidney proximal tubule cells, liver cholangiocytes and intestinal enterocytes are less likely to be the primary SARS-CoV-2 targets as ACE2 localizes at the apical region of cells, where the viruses may not readily reach. Actually, the stomach may constitute a physical barrier against SARS-CoV-2 as the acidic environment in normal stomach (pH < 2.0) could completely inactivate SARS-CoV-2 pseudo-viruses. These findings are in concert with the clinical characteristics of prominent lung symptoms, frequent heart injury, and uncommon intestinal symptoms and acute kidney injury. Together, we provide a comprehensive view on the potential SARS-CoV-2 targets by pscRNA profiling, and propose that, in addition to acute respiratory distress syndrome, attentions should also be paid to the potential injuries in cardiovascular, endocrine and reproductive systems during the treatment of COVID-19 patients.

Highly pathogenic coronavirus N protein aggravates lung injury by MASP-2-mediated complement over-activation

An excessive immune response contributes to SARS-CoV, MERS-CoV and SARS-CoV-2 pathogenesis and lethality, but the mechanism remains unclear. In this study, the N proteins of SARS-CoV, MERS-CoV and SARS-CoV-2 were found to bind to MASP-2, the key serine protease in the lectin pathway of complement activation, resulting in aberrant complement activation and aggravated inflammatory lung injury. Either blocking the N protein:MASP-2 interaction or suppressing complement activation can significantly alleviate N protein-induced complement hyper-activation and lung injury in vitro and in vivo. Complement hyper-activation was also observed in COVID-19 patients, and a promising suppressive effect was observed when the deteriorating patients were treated with anti-C5a monoclonal antibody. Complement suppression may represent a common therapeutic approach for pneumonia induced by these highly pathogenic coronaviruses. One Sentence SummaryThe lectin pathway of complement activation is a promising target for the treatment of highly pathogenic coronavirus induced pneumonia.

Efficacy of ultrasound-guided pectoral nerve block versus thoracic paravertebral block for postoperative analgesia after radical mastectomy / 临床麻醉学杂志

Objective To compare the efficacy and safety of ultrasound guided pectoral nerves Ⅱ (Pecs Ⅱ) block with thoracic paravertebral nerve (TPVN) block for postoperative analgesia after modified radical mastectomy.Methods Eighty female patients scheduled for radical mastectomy,aged 40-65 years,ASA physical status Ⅰ or Ⅱ,were randomly divided into 2 groups using a random number table method (n =40 each):the patients in group T received TPVN block,whereas the pa tients in group P received Pecs Ⅱ block.Both the groups received 0.5 ％ ropivacaine 25 ml.The blocks were performed under all aseptic precautions in the preoperating room 30 min before surgery.The total number of dermatomes that had less pain to pin prick compared with opposite side were not ed.All patients were observed for 30 min after performing the block.The patients were received patient-controlled intravenous analgesia (PCIA).The duration of analgesia and total analgesic consumption in 24 h after surgery were recorded.Adverse effects were recorded between the two groups.Results The duration of analgesia in group P was significantly prolonged than group T [(326.5± 47.8) min vs (201.4±34.5) min,P＜0.01].The 24 h sufentanil consumption were also decreased in group P [(6.9±1.2) μg vs (10.7±1.9) μg,P＜0.01].T2 dermatomal spread were significantly increased in group P [35 (87.6％) cases vs 9 (22.5％) cases,P＜0.05].No complication was recor ded.Conclusion Ultrasound-guided Pecs Ⅱ block and TPVN provided safe and effective anesthesia in patients undergoing modified radical mastectomy,but the effect of Pecs Ⅱ block were more satisfied and per sistent.

Effects Observation of Preemptive Analgesia of Parecoxib-sodium for Radical Mastectomy of Breast Cancer / 中国药房

OBJECTIVE:To investigate the effects of preemptive analgesia of parecoxib-sodium for radical mastectomy of breast cancer. METHODS:A total of 60 female patients underwent selective radical mastectomy of breast cancer under general anes-thesia were randomly divided into observation group(40 cases)and control group(20 cases). 15 min before anesthesia induction, observation group was given intravenous injection of Parecoxib-sodium for injection 40 mg. Control group was given intravenous in-jection of 0.9% Sodium chloride injection 5 mL. The pain visual analogue scale(VAS),the frequency of patient controlled intrave-nous analgesia(PCA)and ADR were observed between 2 groups at different time points after surgery. RESULTS:VAS scores of observation group were significantly lower than those of control group 2,4,6,8 h after operation,and the frequency of PCA 0-4, 4-12,12-24,24-36 h after operation was significantly lower than control group,with statistical significance(P0.05). CONCLUSIONS:The preemptive analgesia of parecoxib-sodium can effectively reduce pain degree of patients with breast cancer after radical mastectomy,the frequency of PCA, and do not increase the occurrence of ADR.

Research development of human infection with H5N6 avian influenza virus / 军事医学

Avian influenza virus is a new recombinant virus , which can cause severe respiratory symptoms ,such as short course,acute disease,and a high mortality rate.The purpose of this paper was to summarize the current status of this virus in terms of its epidemiology ,genetic evolution and virulence .By introducing the advancement in the research of this subtype virus, we hope to provide data and evidence ,for effective surveillance and prevention of this virus .

Explore the molecular mechanisms of dexmedetomidine function as lung protective effect / 实用医学杂志

Objective To explore molecular mechanisms of dexmedetomidine(Dex)function as protec-tive effect on acute lung injury(ALI). Methods Hemorrhagic shock ALI rat model was constructed and divided into 6 groups at random:C group,control group;A group,ALI;G,ALI rat groups were treated with 5μg/kg;I1 group,ALI+PDTC(200 mg/kg);I2 group,ALI+STA-21(100 mg/kg). After 12 h modeled,all rats were anes-thetized and killed,and BALF was collected and the concentrations of TNF-α,IL-6,IL-1β,IL-4 were deter-mined using ELISA. HE staining to observe the morphology of lung tissue. Expression of NF-κB,STAT-3,p-STAT-3 proteins were determined using immunohistochemistry or Western blot. Results In A group,the structure of lung tissue were strongly destroyed ,a large number of neutrophils invasion and red blood cells leakage was found;lung tissue structure in G,I1 and I2 groups were gross integrity. The concentrations of TNF-α,IL-6,IL-1β,IL-4 in A group were significantly higher than C group(P<0.05). The concentrations of TNF-α,IL-6,IL-1β,IL-4 in G group,I1 group and I2 group was significantly lower than A group(P<0.05). The levels of NF-κB and p-STAT-3 protein in A group were obvious enhanced(P < 0.05)compared with G group,I1 group,I2 group,respectively. Conclusion Dex inhibited inflammatory to exert lung protective effect via inhibiting NF-κB,STAT-3 activation-induced by ALI.

Explore the molecular mechanisms of dexmedetomidine function as lung protective effect / 实用医学杂志

Objective To explore molecular mechanisms of dexmedetomidine(Dex)function as protec-tive effect on acute lung injury(ALI). Methods Hemorrhagic shock ALI rat model was constructed and divided into 6 groups at random:C group,control group;A group,ALI;G,ALI rat groups were treated with 5μg/kg;I1 group,ALI+PDTC(200 mg/kg);I2 group,ALI+STA-21(100 mg/kg). After 12 h modeled,all rats were anes-thetized and killed,and BALF was collected and the concentrations of TNF-α,IL-6,IL-1β,IL-4 were deter-mined using ELISA. HE staining to observe the morphology of lung tissue. Expression of NF-κB,STAT-3,p-STAT-3 proteins were determined using immunohistochemistry or Western blot. Results In A group,the structure of lung tissue were strongly destroyed ,a large number of neutrophils invasion and red blood cells leakage was found;lung tissue structure in G,I1 and I2 groups were gross integrity. The concentrations of TNF-α,IL-6,IL-1β,IL-4 in A group were significantly higher than C group(P<0.05). The concentrations of TNF-α,IL-6,IL-1β,IL-4 in G group,I1 group and I2 group was significantly lower than A group(P<0.05). The levels of NF-κB and p-STAT-3 protein in A group were obvious enhanced(P < 0.05)compared with G group,I1 group,I2 group,respectively. Conclusion Dex inhibited inflammatory to exert lung protective effect via inhibiting NF-κB,STAT-3 activation-induced by ALI.

Impact of enhanced recovery after surgery program on postoperative recovery in patients undergoing lapa-roscopic colorectal resection / 临床麻醉学杂志

Objective To investigate the impact of enhanced recovery after surgery (ERAS) program on postoperative recovery in patients undergoing laparoscopic colorectal resection. Methods Eighty-four patients undergoing laparoscopic colorectal resection from March 201 5 to June 201 6 (55 males,29 females,aged 36-78 years,ASA physical status Ⅰ or Ⅱ),were randomly divid-ed into two groups (n = 38 each).Patients in group E were received epidural block combined with general anesthesia,and a series of perfect ERAS strategies,such as strengthen preoperative educa-tion, maintaining perioperative normothermia, perioperative goal-directed fluid therapy, intraoperative and postoperative analgesia.While the patients in group C received routine anesthetic management.The volume of fluid,the nasopharyngeal temperature,the time of recovery of bouel sound,first anal exhaust,eating fluid food,ambulation and remove of the catheter were recorded in two groups.Furthermore,time of PACU after surgery,the total days of hospitalization and total hos-pital costs were recorded.Results The volume of fluid [(1 328 ± 64)ml vs.(2 463 ± 135 )ml]in group E were significantly lower than group C (P <0.05),the nasopharyngeal temperature [(36.2± 0.2)℃ vs.(35.1±0.5)℃]was significantly higher in group E (P <0.05).Compared with group C,the time of recovery of bowel sound [(33.4 ± 12.5 )h vs.(42.8 ± 14.3 )h],first anal exhaust [(43.6±13.9)h vs.(60.7±1 5.4)h],eating fluid food [(26.8±4.1)h vs.(67.4±13.5)h],first ambulation [(7.4±1.6)h vs.(26.5±3.8)h]and remove of the catheter [(29.2±6.1)h vs.(5 1.8 ±7.6) h ], time of PACU [(26.4 ± 8.5 ) min vs.(37.2 ± 1 1.6 ) min ], the total days of hospitalization [(7.5±0.9)d vs.(9.7±1.2)d]were significantly shorter (P <0.05),and hospital costs [(2.1±0.6)ten thousand yuan vs.(2.6±0.8)ten thousand yuan]were significantly decreased (P <0.05).The incidence of adverse reactions such as nausea and vomiting (2.4% vs.21.4%),pru-ritus (7.1% vs.23.8%),agitation (4.8% vs.26.2%)and chills (0% vs.1 9.0%)were significantly lower in group E (P <0.05).Conclusion ERAS program applied to patients undergoing laparoscopic colorectal resection can reduce the intraoperative sufentanil consumption,avoid the occurrence of postoperative hypothermia, accelerate recovery of gastrointestinal function, which can obviously reduce the hospitalization costs and shorten the hospitalization time.

A clinical comparative study on laparoscopic appendectomy vs open appendectomy / 中华普通外科杂志

Objective To compase laparoscopic vs open appendectomy in the treatment of appendicitis.Methods The clinical data of 1 716 appendicitis patients are studied in the form of retrospective summary,who were hospitalized in Jilin University China-Japan Union Hospital from 2009 to 2014.Patients were divided into laparoscopic appendectomy group and open appendectomy group.Duration of operation,surgical complications and postoperative recovery were evaluated.The chi-test and the student t test were used for statistics.Results More patients in open group with chronic lung disease,or a history of previous abdominal surgery than in the laparoscopic group (x2 =3.527,22.804,P ＜ 0.05);the postoperative deep vein thrombosis,intestinal obstruction,abdominal abscess and infection of incision in open group were more often seen than in laparoscopic group (x2 =4.179,4.71,7.351,8.766,P ＜ 0.05);Open group scored higher than laparoscopic group on the index of 24 hours of postoperative pain (t =-3.163,P =0.004);duration of surgery was similar (t =1.754,P =0.092 2);the laparoscopic group was better in recovery time of postoperative intestinal peristalsis,average length of scar and the average hospital stay (t =3.460,-15.335,-3.629,P ＜ 0.05).While the average hospitalization cost in open group is less than in the laparoscopic group (t =5.763,P =0.001).Conclusions Both laparoscopic appendectomy and open appendectomy were effective for the treatment of appendicitis,while laparoscopic appendectomy is superior to open procedure in reducing postoperative pain,postoperative complications promoting rapid recovery,shortening hospital stay and more cosmetic.

Advances in biological spectroscopy detection of pathogenic microorganisms / 军事医学

Detection of pathogenic microorganisms has been a hot research field of microbiology.Conventional detection methods,such as isolation and culture, PCR technology, ELISA and genomic sequencing,are all time-consuming and com-plex.Because of the advantages of quick-testing, accuracy, safety and efficiency, spectroscopy has become a new non-inva-sive testing technology and has witnessed rapid development in pathogen detection and disease diagnosis.This article intro-duces three types of common spectroscopy technologies ( laser excitation fluorescence spectroscopy, infrared spectroscopy and Raman spectroscopy) , and also explains how they work in the detection of pathogenic microorganisms.

Biological characteristics of Ebola virus:research advances / 军事医学

Ebola virus disease , which can cause ebola hemorrhagic fever , is a potent zoonotic infectious virus disease . In 2014 , Ebola virus spread across West Africa and it has become a new major threat to global public health .This article summarizes the structural features of Ebola virus , transmission characteristics , interactions ,animal models .

Nano-hydroxyapatite/collagen composited with recombinant human bone morphogenetic protein-2 and titanium membrane in repairing peripheral bone defects of instant dental implants / 中国组织工程研究

BACKGROUND:Recently,with the rapid development of material science and bioscience,the technology of dental implant has made great progress,especially the immediate implant technology.But the size and shape of implant are usually not fit for tooth extraction wound,so it is an important factor that leads to failure when implant and tooth extraction wound can not form close tangency.Guided bone regeneration or bone grafting materials are usually used to solve this problem.OBJECTIVE:To study the effects of nano-hydroxyapatite/collogen (nHAC) with recombinant human bone morphogenetic protein-2(rhBMP-2) and titanium (Ti) membrane on repairing peripheral bone defects of instant implant.DESIGN,TIME AND SETTING:A randomized,controlled animal study was performed at the Central Laboratory,the Fourth Military Medical University of Chinese PLA between January 2005 and January 2006.MATERIALS:Ti screw implants (diameter 2 mm,length 10 mm,and pitch 0.4 mm) without the part that went through gum were offered by Nonferrous Metal Academy in Baoji,China.The nonabsorbable Ti membranes (2 cm×2 cm) were offered by Zhongbang Biomaterial Limited Company in Xi'an,China.The nHAC materials were gifted by professor Cui Fu-zhai from Material Science and Engineering Department of Tsinghua University and fabricated into 0.5 mm×0.5 mm×0.5 mm small blocks.rhBMP-2 was offered by the Academy of Military Medical Sciences in Beijing,China.rhBMP-2 was dissolved with hydrochloric carbamidine and then nHAC was immersed in it.Vacuumization,freeze-drying,and Ekibon degermation were followed.Each gram of nHAC compounds required approximately 1 mg rhBMP-2.METHODS:Four healthy purebred male dogs were included in this study.According to the methods to repair bone defects rhBMP-2+Ti membrane,nHAC composited with rhBMP-2 was implanted,covering Ti membrane.Six defects were made on the mandible on each side.MAIN OUTCOME MEASURES:At 6 and 12 weeks after implantation,new bone formation and the correlation of new bone to Ti implant were investigated by radiography,bone density measurement and histological examinations.RESULTS:All the bone wounds were full of new bone at 12 weeks,the Ti implants were steady and the osseointegration was good.In the nHAC+rhBMP-2 and nHAC+rhBMP-2+Ti membrane groups,new bone formed and maturated earlier.In the nHAC +Ti membrane,blank control,and nHAC + rhBMP-2 +Ti membrane groups,new bone formed well below Ti membrane and the alveolar crest was plump.In the nHAC + rhBMP-2 +Ti membrane group,new bone formed earliest with the most quantity and the alveolar crest was the plumpest.By 12 weeks,the bone density had achieved the same level as the autologous cancellous bone transplantation,but the alveolar crest was plumper compared to the positive control group.In addition,bone mass was much more.Bone formed slowest in the blank control group and fastest in the positive control group with the crest of ridge being slightly absorbed.CONCLUSION:nHAC is a new good bone graft material in repairing peripheral bone defects of instant implant,especially compositing with rhBMP-2 and/or Ti membrane.A round method to repair the surrounding bone defect of instant implant should be selected according to the specific situation in the clinic.

The measurement of convergence angles of the fixed denture / 实用口腔医学杂志

Objective: To measure the convergence angles of teeth in different teeth positions and different denture designs.Methods:Mesio-distal widths and labio-lingual widths were measured on 226 teeth according to three points in a line on three surfaces (gingival, middle and incise) of each tooth.The distance between every point and the counterpart point in the adjacent surface was measured.Then convergence angles were calculated. Results:The means of the angles were 4.13°±0.77°,4.14°±0.76°, 4.46°±0.95°, 4.76°±0.84° on the first and second premolar, the first and second molar,respectively . There were significant differences between the premolars and molars(P<0.05).On the dentures with the designs of monocrown, triunit-bridge and long bridge the means of the angles were 3.78°±0.74°,4.69°±0.75° and 5.08°±0.85° respectively,the angle on the denture with the design of monocrown was smaller than that of bridge (P<0.05).Conclusion:The convergence angles are different according to different teeth positions and different denture designs, so they should be adjusted according to the clinical requirements.

A study of the interfacial area of auro-galvano-form ceramic crowns / 实用口腔医学杂志

Objective: To study the ionic diffusion and the distri bu tion character in the interfacial area of aurogalvano form ceramic crown, and t o discuss the bond mechanism of porcelain fused to 99.9% gold. Method s: The ionic diffusion and the distribution character in the interfac ial area of aurogalvano form ceramic crown were observed by electron probe and scanning electron microscope. Results: The examination wit h electron microprobe showed that from gold to porcelain aluminum ascended from zero to peak value, aurum dropped from the peak value to zero, and the bandwidt h was about 3～4 ?m.There were obvious mechanical table and tuber. C onclusion: There is ionic diffusion and no crack in the interfacial a rea;there are physical and chemical combinations between porcelain and 99.9% gol d.

Influence of repeated infiltrating firing on the micro-structure of In-Ceram alumina substrate / 实用口腔医学杂志

Objective: To investigate the influence of repeated infiltrating on the microstucture of In-Ceram alumina substrate. Methods:6 disks of aluminum oxide with the height of 3 mm and diameter of 12 mm were perpared and infiltrated with infiltrating glass for 0～5 times for each disk respectively.The fractured surfaces of the samples were observed by scanning elctron microscope. Results:After sintering,a net -shaped porous coping of alumina was formed. The glass infiltration resulted in a dense ceramic mass. The porous coping matrix was infiltrated with low-viscosity glass in void.3-time-infiltration resulted in the best results. Conclusion: With repeated infiltrating firing,the micro-stucture of In-Ceram alumina substrate may become a dense mass.

Effects of cerium oxide content on the color of alumina-glass composite / 实用口腔医学杂志

objective: To investigate the effects of cerium oxide content on the color of alumina glass composite. Methods: Infiltration glass powder with different content of cerium oxide (1%～4%) were fabricated. Alumina glass composite was prepared by infiltrating molten glass into presintered alumina block at 1 250 ℃ for 2 h, and the color of the alumina glass composite were measured with Minolta chromatic instrument(CR 321) . For comparison, the color of VITA In Ceram alumina technical shade guide was recorded too. Results: After infiltration, the b * range of the alumina glass composite was in accord with that of the shade guide. With the increasing content of the cerium oxide, a *, b * and chroma increased, L * decreased, the hue of the alumina glass composite shifted from yellow green to yellow red. Conclusion: Cerium oxide may effectively enhance b * of the alumina glass composite, but its ability of reducing L * and enhancing a * is weak.

The influence of repeated firings on the remained porcelain rate / 实用口腔医学杂志

Objective: To study the influence of repeated firings on the PFM bond strength. Methods: 25 specimens of PFM in the diameter of 13.0 mm and thickness of (1.0?0.02) mm were prepared and fired at 920 ℃ for 1, 3, 5, 7 or 9 times(5 samples for each time). The remained porcelain rate(RPR) was measured by Mackert method and used to evaluate the bond strength.Results: After 3 firings, the RPR of PFM decreased obviously, and additional firings had no obvious effect on the RPR. Conclusion: 3 times firing or more may decrease the bond strength of PFM.