Isolation and identification of granule-associated proteins relevant for poly(3-hydroxyalkanoic acid) biosynthesis in Chromatium vinosum D

Abstract Poly(3-hydroxybutyric acid) granules, which harbored only four major granule-associated proteins as revealed by SDS polyacrylamide gel electrophoresis, were isolated from crude cellular extracts of Chromatium vinosum D by centrifugation in a linear sucrose gradient. N-Terminal amino acid sequence determination identified two proteins of M _r 41 000 and M _{r 40 000} as the phaE _Cv and phaC _Cv translational products, respectively, of C. vinosum D. In a previous study it was shown that both proteins are required for the expression opf poly(3-hydroxyalkanoic acid) synthase activity. The N-terminus of the third protein ( M _r 17 000) exhibited no homology to other proteins. Lysozyme, which was during purification of the granules, exhibited a strong affinity to PHB granules and was identified as the fourth protein enriched with the granules.     

Effects of lignin content on the properties of lignocellulose-based biocomposites

The paper is focused on the analysis of the behaviour of biocomposites (biodegradable composites) which are reinforced with different fillers fractions, with varying lignin contents. These materials have been carried-out by extrusion and injection moulding. The matrix, an aromatic copolyester (polybutylene adipate-co-terephthalate), is biodegradable. The lignocellulose fillers are a by-product of an industrial fractionation process of wheat straw. From the raw agro-material and by lignin extractions, various fillers fractions have been obtained by varying the fractionation conditions, both on the liquid media (aqueous or organic) and on the temperature. The fillers lignin contents vary from 30 to 14 wt% with a resultant increase of the cellulose content. We have analysed the impact of the different extraction conditions on the fillers surface and size distribution, and also on the final thermal and mechanical properties of the biocomposites. These materials present significant differences of behaviour which can fulfil some requirements for applications, such as non-food packaging or other short-lived applications (agriculture, sport …) where long-lasting polymers are not entirely adequate.     

谷红注射液和丁苯酞注射液联合Solitaire AB型支架取栓治疗急性缺血性脑卒中的临床研究

摘要 目的：探讨谷红注射液和丁苯酞注射液联合Solitaire AB型支架取栓治疗急性缺血性脑卒中（AIS）的临床疗效。方法：选择2018年1月到2020年12月期间攀枝花市中西医结合医院收治的AIS患者98例,依照随机数字表法分为观察组（50例）和对照组（48例）。对照组采用Solitaire AB型支架取栓治疗,观察组给予谷红注射液和丁苯酞注射液联合Solitaire AB型支架取栓治疗,两组均治疗14 d。治疗后进行临床疗效评价,比较两组治疗后的血管再通率和并发症发生率,比较两组治疗前后的美国国立卫生研究院卒中量表（NIHSS）评分、Barthel指数评分及全血高切黏度、全血低切黏度、血小板聚集率。结果：观察组的临床总有效率为84.00%（42/50）,对照组为60.42%（29/48）,两组比较差异有统计学意义（P<0.05）。观察组的血管再通率明显高于对照组（P<0.05）。两组治疗后血小板聚集率、全血低切黏度及全血高切黏度均明显低于治疗前（P<0.05）,且观察组治疗后血小板聚集率、全血低切黏度及全血高切黏度均明显低于对照组（P<0.05）。治疗后观察组Barthel指数评分明显高于对照组（P<0.05）,NIHSS评分明显低于对照组（P<0.05）。观察组的并发症发生率为6.00%（3/50）,对照组为4.17%（2/48）,两组比较差异无统计学意义（P>0.05）。结论：谷红注射液和丁苯酞注射液联合Solitaire AB型支架取栓治疗AIS的临床疗效显著,能够提高血管再通率,减轻神经功能缺损,改善患者的日常生活能力和血液流变学指标,且并发症较轻。     

Role of tissue engineered collagen based tridimensional implant on the healing response of the experimentally induced large Achilles tendon defect model in rabbits: a long term study with high clinical relevance

Background

Tendon injury is one of the orthopedic conditions poses with a significant clinical challenge to both the surgeons and patients. The major limitations to manage these injuries are poor healing response and development of peritendinous adhesions in the injured area. This study investigated the effectiveness of a novel collagen implant on tendon healing in rabbits.

Results

Seventy five mature White New-Zealand rabbits were divided into treated (n = 55) and control (n = 20) groups. The left Achilles tendon was completely transected and 2 cm excised. The defects of the treated animals were filled with collagen implants and repaired with sutures, but in control rabbits the defects were sutured similarly but the gap was left untreated. Changes in the injured and normal contralateral tendons were assessed weekly by measuring the diameter, temperature and bioelectrical characteristics of the injured area. Clinical examination was done and scored. Among the treated animals, small pilot groups were euthanized at 5, 10, 15, 20, 30, 40 and 60 (n = 5 at each time interval) and the remainder (n = 20) and the control animals at 120 days post injury (DPI). The lesions of all animals were examined at macroscopic and microscopic levels and the dry matter content, water delivery and water uptake characteristics of the lesions and normal contralateral tendons of both groups were analyzed at 120 DPI.No sign of rejection was seen in the treated lesions. The collagen implant was invaded by the inflammatory cells at the inflammatory phase, followed by fibroplasia phase in which remnant of the collagen implant were still present while no inflammatory reaction could be seen in the lesions. However, the collagen implant was completely absorbed in the remodeling phase and the newly regenerated tendinous tissue filled the gap. Compared to the controls, the treated lesions showed improved tissue alignment and less peritendinous adhesion, muscle atrophy and fibrosis. They also showed significantly better clinical scoring, indices for water uptake and water absorption, and bioelectrical characteristics than the controls.

Conclusion

This novel collagen implant was biodegradable, biocompatible and possibly could be considered as a substitute for auto and allografts in clinical practice in near future.     

Numerical investigations of the mechanical properties of a braided non-vascular stent design using finite element method

This paper discusses various issues relating to the mechanical properties of a braided non-vascular stent made of a Ni–Ti alloy. The design of the stent is a major factor which determines its reliability after implantation into a stenosed non-vascular cavity. This paper presents the effect of the main structural parameters on the mechanical properties of braided stents. A parametric analysis of a commercial stent model is developed using the commercial finite element code ANSYS. As a consequence of the analytical results that the pitch of wire has a greater effect than other structural parameters, a new design of a variable pitch stent is presented to improve mechanical properties of these braided stents. The effect of structural parameters on mechanical properties is compared for both stent models: constant and variable pitches. When the pitches of the left and right quarters of the stent are 50% larger and 100% larger than that of the central portion, respectively, the radial stiffness in the central portion increases by 10% and 38.8%, while the radial stiffness at the end portions decreases by 128% and 164.7%, the axial elongation by 25.6% and 56.6% and the bending deflection by 3.96% and 10.15%. It has been demonstrated by finite element analysis that the variable pitch stent can better meet the clinical requirements.     

Computational haemodynamics in two idealised cerebral wide-necked aneurysms after stent placement

Endovascular stents are being commonly used to treat cerebral wide-necked aneurysms recently. The effect of a stent placed in the parent artery is not only to protect the parent artery from occlusion, due to extension of coils and thrombosis, but also to act as flow diverter to vary the haemodynamics in the aneurysm. In this article, two idealised cerebral wide-necked aneurysms were created, one was sidewall aneurysm with curved parent vessel and the other was terminal aneurysm with the bifurcated parent vessel. The plexiglass models of the two aneurysms were ‘treated’ with commercial porous intravascular stents. The stented physical models were scanned by Micro-CT and the numerical models of the two idealised cerebral wide-necked aneurysms after stent placement were constructed from the scanned image files. The pulsatile flow of non-Newtonian fluid inside the models was simulated by using computational fluid dynamics package. From the simulated flow dynamics, various haemodynamic characteristics such as velocity contours, wall shear stress and oscillatory shear index (OSI) were computed. The velocity of the jet entering the sacs reduced after stent was deployed across the necks of both sidewall and terminal aneurysms; the wall shear stress on the distal neck of sidewall aneurysm reduced, the wall shear stress on the dome of the terminal aneurysm increased and the OSI on the dome of the terminal aneurysm reduced. Therefore, stent placement not only promotes thrombus formation in both aneurysm models but also reduces the regrowth risk of the sidewall aneurysm and the rupture risk of the terminal aneurysm.     

Modelling drug elution from stents: effects of reversible binding in the vascular wall and degradable polymeric matrix

Today the most popular approach for the prevention of the restenosis consists in the use of the drug eluting stents. The stent acts as a source of drug, from a coating or from a reservoir, which is transported into and through the artery wall. In this study, the behaviour of a model of a hydrophilic drug (heparin) released from a coronary stent into the arterial wall is investigated. The presence of the specific binding site action is modelled using a reversible chemical reaction that explains the prolonged presence of drug in the vascular tissue. An axi-symmetric model of a single stent strut is considered. First an advection–diffusion problem is solved using the finite element method. Then a simplified model with diffusion only in the arterial wall is compared with: (i) a model including the presence of reversible binding sites in the vascular wall and (ii) a model featuring a drug reservoir made of a degradable polymeric matrix. The results show that the inclusion of a reversible binding for the drug leads to delayed release curves and that the polymer erosion affects the drug release showing a quicker elution of the drug from the stent.     

The evolution of an ideal stent design and its impact on the aortic endothelium during and after percutaneous replacement

Vascular support structures are important devices for treating valve stenosis. A large population of patients is treated for valvular disease and the preferred mode of treatment is percutaneous valve replacement. Stent devices are proving to be an improved technology in minimally invasive cardiac surgery. This new technology provides highly effective results at minimal cost and with a short duration of hospitalisation. Stents as a supporting structure for tissue valves have evolved over the years into remarkably useful and effective devices. During this process, a number of specific designs have come and gone, and a few have remained. Many design changes were successful, and many were not. This article describes the merits and demerits of various stent designs and details the specific reasons why a particular novel design is expected to be the most suitable implant during and after percutaneous aortic valve replacement.     

A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis

Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings.     

覆膜支架腔内修复术与药物保守治疗对Stanford B型主动脉夹层动脉瘤患者肝肾功能、炎性因子以及预后的影响

目的:比较覆膜支架腔内修复术与药物保守治疗对Standford B型主动脉夹层动脉瘤的疗效及对患者肝肾功能、炎性因子及预后的影响。方法:选择2012年1月～2014年8月我院收治的Standford B型主动脉夹层动脉瘤患者68例,按照随机数字表法分为对照组与研究组,各34例。对照组入院后采取药物保守治疗,研究组应用覆膜支架腔内修复术治疗。观察两组住院期间死亡率、再次手术或介入率以及治疗前、治疗2周后肝肾功能、血清炎性因子变化。所有患者随访36个月,比较两组患者预后情况。结果:研究组再次手术或介入率为2.94%,低于对照组的22.58%(P0.05)。治疗2周后,研究组丙氨酸转氨酶(ALT)、天门冬氨酸氨基转移酶(AST)、尿素氮(BUN)、肌酐(Cr)、胱抑素C、肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、γ-干扰素(INF-γ)、C反应蛋白(CRP)水平较治疗前降低(P0.05),且研究组低于对照组(P0.05)。两组患者均随访36个月,随访12个月时两组患者生存率分别为100.00%和80.65%,随访36个月时两组患者生存率分别为91.18%和29.03%,经Log Rank分析显示,两组生存率比较差异有统计学意义(P0.05)。结论:覆膜支架腔内修复术治疗Standford B型主动脉夹层动脉瘤的疗效确切,能够改善患者肝肾功能,降低炎症反应,患者近中期随访生存率较高,其效果优于保守治疗。