粉浆涂塑渗透陶瓷烧结线性收缩率的测定

制作４０个渗透陶瓷样本测定粉浆涂塑渗透陶瓷的氧化铝烧结及玻璃料渗透的两个烧结阶段的线性收缩率。结果表明，渗透陶瓷烧结完成后的线性收缩率为０．０８％＿０．３２％。收缩主要发生于氧化铝的烧结过程，此过程的收缩率为０．２０％，而玻璃料的渗透烧烤过程 不引起长度的明显变化。     

变形链球菌表面蛋白和葡糖基转移酶基因疫苗防龋动物实验:Keyes龋齿计分研究

目的 :了解变形链球菌基因疫苗 pcDNA3 pac和 pcDNA3 gtfB的免疫防龋效果。 方法 :2 8d龄Wistar大鼠 3 6只 ,随机分为pcDNA3 pac组 (A组 )、pcDNA3 gtfB组 (B组 )、pcDNA3 pac联合 pcDNA3 gtfB组 (C组 )、变形链球菌灭活全菌组 (D组 )、pcDNA3空载体组 (E组 )和PBS液组 (F组 )进行 3次双侧颌下腺腺周注射免疫。建立定菌鼠模型 ,诱龋 3个月 ,根据Keyes经典评分方法从龋损范围及深度进行龋损综合评估和比较。结果 :龋损牙面计分在 pcDNA3与PBS组最高 ,其次为单基因疫苗免疫组 ,联合免疫和灭活全菌细胞最低 (P <0 .0 1或P <0 .0 5 ) ;窝沟龋各级计分 :E级龋在单基因疫苗组 ,联合疫苗组、灭活全菌细胞组无区别 (P >0 .0 5 ) ,而PBS组和 pcDNA3组则较低 (P <0 .0 1) ;Dm级、Ds级则是联合免疫组与灭活全菌细胞组最低 ,单基因疫苗免疫组较高而PBS和 pcDNA3组最高 (P <0 .0 1或P <0 .0 5 ) ;Dx级四个免疫组发生率很低或不发生 ,显著低于PBS组和pcDNA3组 (P <0 .0 1)。结论 :重组质粒pcDNA3 gtfB和pcDNA3 pac具显著有效的免疫防龋作用 ,以联合基因疫苗免疫最好 ,是理想的防龋决策之一。     

■创伤性牙髓炎和根尖周炎的临床研究

为进一步探讨创伤引起牙髓和根尖周炎的病因、病理及临床诊治情况，作者通过对８９例患者的１００颗此类患牙的病例观察，总结出这类疾病的发病特点和临床表现；提出了创伤性牙髓炎或根尖周炎的诊断名词与诊断指标，并对这些病例进行了２年的追踪观察及疗效分析，提出了综合治疗方案。为这类疾病的临床诊治提供了依据。     

方丝弓技术实施扩弓作用初探

本临床研究应用了直的双根钛镍丝扩弓法,主弓配合辅弓扩弓法,多loop弓丝牙弓前部扩弓法,改良多用弓技术,四眼簧扩弓器,快速扩弓螺旋器,用预成的略大于牙弓的弓丝扩弓和上下颌后牙交互牵引扩大牙弓,共8种方法.作者结合临床经验及体会,分析了各种扩弓方法的原理,提出了每种扩弓方法的适应症以及加力时应注意的事项.这些常用的扩弓方法,在临床上是行之有效的.既满足了临床扩弓的要求,也促进了方丝弓矫治技术的普及和开展.     

变形链球菌表面蛋白和葡糖基转移酶基因疫苗免疫防龋动物实验:体质量影响研究

目的 :了解变形链球菌基因疫苗单独及联合免疫对定菌鼠体质量的影响。方法 :2 8d龄Wistar大鼠 3 6只 ,随机分为pcDNA3 pac组、pcDNA3 gtfB组、pcDNA3 pac联合pcDNA3 gtfB组、变形链球菌灭活全菌阳性对照组、pcDNA3空载体阴性对照组和PBS液空白对照组 ,进行 3次双侧颌下腺腺周注射免疫 ,建立定菌鼠模型及诱龋实验 3个月 ,于实验开始和结束时测定体质量。结果 :基因疫苗免疫组体质量与 pcD NA3及PBS组无显著差异 (P >0 .0 5) ,而灭活全菌细胞免疫组体质量显著下降 (P <0 .0 1)。结论 :pcD NA3 gtfB和pcDNA3 pac对大鼠体质量无不良影响 ,较灭活全菌疫苗安全     

实验性He创伤对牙髓和牙周组织影响的研究

为了探讨Ｈｅ创伤持续时间与牙髓、牙周组织变化间的关系，作者对４４只大鼠的下颌磨牙制造了实验性Ｈｅ创伤，利用组织病理学和软射线的研究方法，观察不同实验期受创伤大鼠磨牙的牙髓、牙周组织变化，并与软射线片进行对照分析。结果表明，牙髓组织随Ｈｅ务时间延长而病变逐渐加重；牙周组织受到长期Ｈｅ创伤后呈现适应性变化，牙周组织焦吩一软射线片显示的牙周变化部位相应。本研究结果为Ｈｅ创伤性牙髓炎和根尖周炎的病因，病理     

Epidemiologic Features,Radiological Findings and Clinical Outcomes of 19 Patients with COVID-19 in a Single Center in Beijing,China

Objective To describe the epidemiologic, clinical, laboratory, and radiological characteristics and prognoses of COVID-19 confirmed patients in a single center in Beijing, China. Methods The study retrospectively included 19 patients with nucleic acid-confirmed SARS-CoV-2 infection at our hospital from January 20 to March 5, 2020. The final follow-up date was March 14, 2020. The epidemiologic and clinical information was obtained through direct communication with the patients or their family members. Laboratory results retrieved from medical records and radiological images were analyzed both qualitatively by two senior chest radiologists as well as quantitatively via an artificial intelligence software. Results We identified 5 family clusters (13/19, 68.4％) from the study cohort. All cases had good clinical prognoses and were either mild (3/19) or moderate (16/19) clinical types. Fever (15/19, 78.9％) and dry cough (11/19, 57.9％) were common symptoms. Two patients received negative results for more than three consecutive viral nucleic acid tests. The longest interval between an initial CT abnormal finding and a confirmed diagnosis was 30 days. One patient's nucleic acid test turned positive on the follow-up examination after discharge. The presence of radiological abnormalities was non-specific for the diagnosis of COVID-19. Conclusions COVID-19 patients with mild or no clinical symptoms are common in Beijing, China. Radiological abnormalities are mostly non-specific and massive CT examinations for COVID-19 screening should be avoided. Analyses of the contact histories of diagnosed cases in combination with clinical, radiological and laboratory findings are crucial for the early detection of COVID-19. Close monitoring after discharge is also recommended.     

Acrylamide exposure impairs blood-cerebrospinal fluid barrier function

Previous studies show that chronic acrylamide exposure leads to central and peripheral neu- ropathy. However, the underlying mechanisms remained unclear. In this study, we examined the permeability of the blood-cerebrospinal fluid barrier, and its ability to secrete transthyretin and transport leptin of rats exposed to acrylamide for 7, 14, 21 or 28 days. Transthyretin levels in cerebrospinal fluid began to decline on day 7 after acrylamide exposure. The sodium fluorescein level in cerebrospinal fluid was increased on day 14 after exposure. Evans blue concentration in cerebrospinal fluid was increased and the cerebrospinal fluid/serum leptin ratio was decreased on days 21 and 28 after exposure. In comparison, the cerebrospinal fluid/serum albumin ratio was increased on day 28 after exposure. Our findings show that acrylamide exposure damages the blood-cerebrospinal fluid barrier and impairs secretory and transport functions. These changes may underlie acrylamide-induced neurotoxicity.