聚吡咯的制备及其在血管组织工程中的研究

聚吡咯(ploypyrrole,PPy)是一种具有广泛应用前景的导电高分子材料。本文从PPy的制备、特性和在血管组织工程中的应用等角度出发,详细介绍了掺杂剂、添加剂、电解液、温度、pH值、氧化剂等因素对PPy材料制备和特性的影响,以及PPy在血管组织工程中的研究现状。

Physical Characteristics of Knitted Polyester Vascular Prostheses:Can the Wall Be Considered as a Scaffold for Tissue Regeneration?

Recent developments in endovascular surgery (EVAR) have opened new avenues to successfully treat aneurysms with percutaneous deployment of stent-grafts.Manufacturers have preferred to use woven fabrics or micro-porous tubes which are supported by metallic frames or stents.Woven fabrics are much thinner than knits and this permits the use of a smaller delivery catheter.However,since woven constructions are stiffer and have little porosity,the tissue ingrowth is poor or absent.On the other hand,knitted constructions can be considered as a scaffold for tissue ingrowth,and hence they represent an attractive alternative because of their open structure and better conformability in the case of balloon deployment.The present study was undertaken to analyze the properties of two knitted and crimped polyester arterial prototype prostheses,one with and the other without a gelatin coating as sealant.Two commercial controls were also included in the study,namely the uncoated knitted polyester vascular prosthesis VP1200K,and its sealed version,the gelatin coated polyester knitted Gelsoft device,manufactured by Vascutek Ltd.,Scotland,UK.In vitro testing consisted of analyzing the geometry and morphology of the yarn and fabric structures,and measuring the physical and mechanical properties of the grafts,including the water permeability,the longitudinal and radial compliance,and the suture retention strength.In order to compare the different properties of the four samples,tests were also performed on the gelatin coated or sealed devices before and after gelatin removal.The results provided a useful comparison between the prototypes and the commercial control devices.The latter used ten times the amount of gelatin which had been applied as a coating in order to achieve the same low level of impermeability to water.The different amounts of gelatin also explained the different mechanical performance,such as compliance,for these prototype and control prostheses.

Limitations of multimodality imaging in the diagnosis of pannus formation in prosthetic aortic valve and review of the literature

Pannus formation is a rare complication and occurs almost exclusively in mechanical prosthetic valves.It consists of fibrous tissue that covers the surface of the prosthesis either concentrically or eccentrically,resulting in valve dysfunction.The pathophysiology seems to be associated to a chronic inflammatory process that explains the late and insidious clinical presentation.This diagnosis should be considered in patients with high transvalvular gradients on transthoracic echo,and workup should be completed with fluoroscopy and transesophageal echocardiography.Treatment is always surgical and recurrence is rare.We present a case of pannus formation in a prosthetic aortic valve and a review of the literature regarding this disorder.

妊高征后早期发生的代谢综合征

OBJECTIVE: The objective of the present study was to evaluate the cardiovasc ul ar risk profile and the prevalence of metabolic syndrome among women with a hist ory of pregnancy-induced hypertension (PIH). METHODS:From a cohort of 3,799 nul liparous women prospectively recruited between 1989 and 1997, we performed an ob servational study on 168 case-control pairs 7.8 years after delivery. Participa nts were scheduled for a visit with a research nurse to evaluate their cardiovas cular risk profile using a questionnaire, anthropometric measurements and blood specimen analysis. RESULTS: One hundred sixty-eight women with prior PIH (105 w ith gestational hypertension and 63 with preeclampsia) and 168 controls matched for age and year of index delivery were evaluated. The women with PIH (34.6±4.4 years) were more obese and had higher systolic (115 mm Hg versus 108 mm Hg) and diastolic (75 mm Hg versus 70 mm Hg) blood pressures (P < .001) than the 168 co ntrols (35.1±4.5 years). They had lower high-density lipoprotein cholesterol l evel (1.30 mmol/L versus 1.42 mmol/L; P < .001), increased fasting blood glucose concentration (5.2 mmol/L versus 5.0 mmol/L; P = .002), and higher insulin leve ls (119 versus 91 pmol/L; P < .001). The prevalence of the metabolic syndrome wa s higher in the PIH group (unadjusted odds ratio = 4.9; 95%confidence interval 2.1-10.9) compared with controls, even after adjustment for confounders (adjust ed odds ratio = 3.6; 95%confidence interval 1.4 -9.0). CONCLUSION: In white wo men in their mid-30s, the prevalence of the metabolic syndrome is 3-to 5-fold increased in those with a history of PIH in their first pregnancy. This emphasi zes the importance of long-term follow-up assessment for cardiovascular risk f actors in these women.

Acknowledgments to reviewers of World Journal of Obstetrics and Gynecology

Many reviewers have contributed their expertise and time to the peer review,a critical process to ensure the quality of World Journal of Obstetrics and Gynecology.The editors and authors of the articles submitted to the journal are grateful to the following reviewers for evaluating the articles(including those published in this issue and those rejected for this issue)during the last editing time period.

Simulation of blood flow in a small-diameter vascular graft model with a swirl (spiral) flow guider

Small-diameter vascular grafts are in large demand for coronary and peripheral bypass procedures, but present products still fail in long-term clinical application. In the present communication, a new type of small-diameter graft with a swirl flow guider was proposed to improve graft patency rate. Flow pattern in the graft was simulated numerically and compared with that in a conventional graft. The numerical results revealed that the swirl flow guider could indeed make the blood flow rotate in the new graft. The swirling flow distal to the flow guider significantly altered the flow pattern in the new graft and the ve- locity profiles were re-distributed. Due to the swirling flow, the blood velocity near the vessel wall and wall shear rate were greatly enhanced. We believe that the increased blood velocity near the wall and the wall shear rate can impede the occurrence of acute thrombus formation and intimal hyperplasia, hence can improve the graft patency rate for long-term clinical use.