ABSTRACT
@#In recent years, due to precise control of the amorphous mineral precursor in the demineralization of dentine collagen fibers in orderly deposition, forming apatite crystals similar to the natural mineralized dentin, the bottom-up remineralization approach which does not depend on the existence of seed crystallites, dentin biomimetic mineralization techniques gradually become a hotspot in the research field of restoration of demineralized dentin caused by dental caries. This paper reviews the changing concepts and practices of the remineralization of demineralized dentin, emphasizing biomimetic remineralization studies. The results of the literature review show that the traditional dentin remineralization method is usually a disordered mixture of demineralized dentin and minerals, so mineralized dentin is not comparable to natural mineralized dentin in terms of the morphological characteristics and mechanical properties. With its gradual increase in recent years, dentine biomimetic mineralization technology perfectly resembles the minerals in the dentin overlapping sequence arranged with the dentine collagen fiber structure characteristics, leading to greatly improved microstructural, physical and chemical properties. As a result, dentine biomimetic mineralization technology is expected to achieve new breakthroughs in the fields of resin-dentin bonding mixing layers and the decay of dentin. At present, the technical obstacles that need to be overcome in the clinical application of the biomimetic remineralization of dentin are how to continuously supplement all the active ingredients needed for mineralization in the process of remineralization and how to keep the mechanical properties of the parent material unchanged while slowly releasing all ingredients. Researchers have successively proposed three-step transportation of the biomimetic remineralization of raw materials, as well as the preparation of mineralization precursors stabilized by polymers in advance and the reuse of mesoporous silicon nanomaterials for the transportation of the mineralized ingredient system. The concept described above provides the preliminary in vitro experimental basis for the transformation of the biomimetic remineralization strategy of dentin in clinical applications.
ABSTRACT
Objective To explore the feasibility and effectiveness of establishing an aortic valve regurgitation canine model by minimally invasive peripheral vascular catheter method. Methods A total of 10 healthy canines were selected in this study. An aortic insufficiency animal model was established by percutaneous femoral artery puncture and aortic dilatation. Aortic angiography and transthoracic echocardiography were used to evaluate aortic valve regurgitation immediately after operation. Results Aortic valve regurgitation animal models were successfully established in all the 10 canines. Two canines died of acute left ventricular failure due to the large aortic regurgitation after the operation. Six surviving canines had moderate aortic regurgitation and two had slight aortic regurgitation; they survived for more than 1 month. Conclusion It is feasible to establish an aortic regurgitation canine model by minimally invasive peripheral vascular catheter method.
ABSTRACT
Objective To study the choice of diagnostic and therapeutic strategy for young patients with acute myocardial infarction (AMI) according to the onset characteristics. Methods We retrospectively analyzed the clinical data of 36 young and 1 283 elderly patients with AMI, who were treated between Dec. 2006 and Jan. 2012 in our hospital. The risk factors, clinical characteristics and diagnosis/treatment strategies were analyzed. Results (1) The young patients accounted for 2.7% of all the AMI patients in our study, with most of them being male (97.2%). AMI with ST-segment elevation accounted for 94.4% (34/36) among the young AMI patients, often with risk factors like smoking and dyslipidemia, scarcely with hypertension or diabetes. In the young patients the incidence rates of cardiogenic shock, heart failure and arrhythmia were 5.6% (2/36), 16.7% (6/36), and 5.6% (2/36, respectively, and there was no death during treatment or follow-up. (2) Among the 33 young patients receiving coronary angiography, 21 (63.6%) had single vessel lesions, mostly involving the left anterior descending artery and resulting in anterior myocardial infarction. Among the 15 young AMI patients who received emergent coronary angiograpy, 6 (40%) had heavy thrombus burdern but had slighter coronary stenosis, and they did not receive stent treatment. Conclusion AMI should be considered when young male patients with smoking history, dyslipidemia and chest pain. Young AMI patients often have single vessel lesions and better prognosis, and they need timely revascularization.
ABSTRACT
Objective To investigate the relationship between autonomic nervous reflex and early recurrence of atrial fibrillation after radiofrequency catheter ablation (RFCA) using diving reflex test and cold pressor test. Methods A total of 102 patients with paroxysmal atrial fibrillation were recruited in the present study. All patients underwent diving reflex test and cold pressor test before and after RFCA. The relationship between mean heart rate and early recurrence of atrial fibrillation was observed. Results Circumferential pulmonary vein isolation was successfully achieved in all the 102 patients. The mean heart rate was decreased by diving reflex test and increased by cold pressor test. The diving reflex of the participants was significantly decreased after RFCA (P<0.05), and the cold pressor test results had no noticeable change. The diving reflex in patients with early recurrence of atrial fibrillation was more intensive than those without (P<0.05). Conclusion The parasympathetic activity is decreased in atrial fibrillation patients after RFCA, and the decrease may be related to the early recurrence of atrial fibrillation after RECA.