p-Amino salicylic acid — oxidized cellulose system: a model for long term drug delivery

The immobilization of p-amino salicylic acid (PASA) on periodic oxidized cellulose (O.C) as a biocompatible carrier was investigated. The immobilization of the PASA is based on Schiff's base formation between the amino group of PASA and the aldehyde group of O.C. The in vivo and in vitro release of p-amino salicylic acid was studied. Such a system may be useful for the sustained delivery of the drugs in the body, since O.C. itself is a biosoluble carrier.     

HA/PDLLA复合材料的体内成骨过程研究

目的研究HA／PDLLA复合材料植入体内后与细胞、组织的相互作用，探讨HA／PDLLA复合材料在体内的成骨过程，为其临床应用及设计具有生物功能的人工骨替换材料和骨组织工程支架材料提供依据。方法采用液相吸附法制备了HA／PDLLA复合材料，以纯PDLLA和空白组进行对照，进行体内植入实验，通过组织学观察和四环素标记考察其成骨过程。结果HA／PDLLA复合材料植入机体后，体内的无菌性炎症轻微，新骨形成速率高于PDLLA材料。HA微粒的存在，加强了复合材料的机械强度，使之可以避免过早的丧失力学强度。第24w时，材料被组织分隔包裹，新生骨组织长入材料，骨愈合情况良好。结论HA／PDLLA复合材料具有良好的生物相容性、生物降解性能、生物学活性和骨传导性能。     

Biodegradation studies on periodate oxidized cellulose

Sodium periodate oxidized cellulose was found to degrade into small molecules when implanted subcutaneously in rats. Thus the potentiality of using oxidized cellulose as a biodegradable drug carrier is envisaged.     

Synthesis and properties of biodegradable poly(ester-urethane)s based on poly(ε-caprolactone) and aliphatic diurethane diisocyanate for long-term implant application: effect of uniform-size hard segment content

Abstract

In this article, a series of medical poly(ester-urethane)s (PEUs) with varying uniform-size hard segment content were prepared via one-step chain extension of poly(ε-caprolactone)s with aliphatic urethane diisocyanate, and the corresponding films were obtained by solvent evaporation technique. The chemical structures of polymers were confirmed by ¹H NMR, FT-IR and GPC. The effect of uniform-size hard segment content on the physicochemical properties of PEU films, including thermal properties, mechanical properties, crystallization behavior, water-swelling behavior and in vitro degradability, was extensively researched. The PEU films exhibiting similar thermal transition and thermal stability indicated that the uniform-size hard segment content had little effect on the thermal properties. Two obvious glass transition temperatures observed in DSC curves manifested a microphase separation structure, which endowed the PEU films excellent mechanical properties with ultimate stress of 34.6–51.2?MPa and strain at break of 898–1485%. And with the increase of uniform-size hard segment content, the initial modulus and ultimate stress increased, while the strain at break decreased. Due to the compact physical-linking network structure formed by the denser hydrogen bonds, the PEU films exhibited low water-swellability of less than 1.5?wt% and low degradation rate in vitro. The weight loss of the PEU films in degradation test was less than 1?wt% at the first four months and the time of films becoming fragments was more than 15?months. Cytotoxicity test of film extracts was conducted with L929 mouse fibroblasts, and the relative growth rate approached or exceeded 75%, indicating an acceptable cytocompatibility. For the excellent mechanical properties, slow biodegradability, non-toxic degradation products and adequate cytocompatibility, the PEUs containing uniform-size hard segments possess a high potential to be applied as long-term implant biomaterials.     

Bilastine: an environmental risk assessment

Context: Bilastine is a new oral selective, non-sedating histamine H₁ antagonist for the symptomatic treatment of allergic rhinoconjunctivitis and urticaria. The European Medicines Agency requires an Environmental Risk Assessment (ERA) for all novel medicines for human use. Objective: To calculate the bilastine predicted environmental concentration in surface water (PEC_sw; phase I ERA), and to determine the effects of bilastine on aquatic systems (phase II [tier A]). Materials and methods: Bilastine PEC_sw was calculated using the maximum daily dosage (20?mg), assuming that all administered bilastine was released into the aquatic environment. A persistence, bioaccumulation and toxicity assessment was conducted using the log K_ow from the molecular structure. In phase II (tier A), a ready biodegradability test was performed, and bilastine’s potential toxicity to various aquatic and sediment-dwelling micro-organisms was evaluated. Results: Bilastine PEC_SW was calculated as 0.1?μg?L^?1, and the compound was not readily biodegradable. Bilastine had no significant effects on Chironomus riparius midges, or on the respiration rate of activated sludge. For green algae, the bilastine no observed effect concentration (NOEC) was 22?mg?L^?1; bilastine had no effect on zebra fish development, or on the reproduction rate of daphnids. Discussion: Bilastine NOEC values against zebra fish, algae, daphnids, and aerobic organisms in activated sludge were at least 130?000-fold greater than the calculated PEC_SW value. Conclusion: No environmental concerns exist from bilastine use in patients with allergic rhinoconjunctivitis or urticaria.     

食管良性狭窄药物镁合金可降解支架研究现状及展望

支架在食管良性狭窄的治疗中发挥着越来越重要的作用。临床应用的支架主要为金属支架,可分为永久性支架和暂时性可回收支架。永久性金属支架长期植入易引起炎性增生、支架内再狭窄、穿孔、出血等并发症,暂时性可回收金属支架植入后1周内需取出,以避免食管瘢痕修复及支架内组织增生导致其取出困难、远期食管再狭窄复发率高。药物洗脱支架在心血管系统疾病的治疗中已处于临床使用阶段,消化道药物洗脱支架目前处于研制及动物实验阶段;镁合金可降解支架已经在心血管系统广泛应用。随着生物工程材料的发展,药物镁合金可降解支架已成为食管支架研究的热点和前沿。本文对药物镁合金可降解支架研发的现状和展望进行全面详细阐述,重点介绍支架工艺：支架成型,覆膜改性,载药处理。     

高温高压对壳聚糖／甘油磷酸钠温敏凝胶释药性能的影响

目的：研究高温高压后的壳聚糖／甘油磷酸钠凝胶温敏、释药性能。方法：观察不同比例的壳聚糖和甘油磷酸钠混合液的凝胶时间、pH值变化。粘度测试比较不同比例壳聚糖／甘油磷酸钠混合液粘度变化。在37℃形成凝胶后,观察该体系作为奥硝唑药物模型载体的释药性能。结果：随着壳聚糖／甘油磷酸钠混合液中甘油磷酸钠的比例增加,溶液pH值增加,在37℃下,壳聚糖／甘油磷酸钠凝胶时间缩短,但当壳聚糖／甘油磷酸比例为2：1、1：1时,溶液不凝胶。粘度实验表明,4种比例（9：1、8：1、7：1、6：1）壳聚糖／甘油磷酸溶液随着时间增加,粘度明显增加,到10 min后粘度基本不变化,9：1比例组粘度最大为（53±0．9）Pa·s。药物释放实验表明,以奥硝唑为释药模型,该凝胶可持续释放200 min以上。结论：改进消毒方法后的壳聚糖／甘油磷酸钠,增加甘油磷酸钠比例可以提高溶液pH值,可在37℃下快速形成凝胶。该凝胶具有温敏性,具有缓慢释放药物能力。     

Biodegradation of L-Valine Alkyl Ester Ibuprofenates by Bacterial Cultures

Nowadays, we consume very large amounts of medicinal substances. Medicines are used to cure, halt, or prevent disease, ease symptoms, or help in the diagnosis of illnesses. Some medications are used to treat pain. Ibuprofen is one of the most popular drugs in the world (it ranks third). This drug enters our water system through human pharmaceutical use. In this article, we describe and compare the biodegradation of ibuprofen and ibuprofen derivatives—salts of L-valine alkyl esters. Biodegradation studies of ibuprofen and its derivatives have been carried out with activated sludge. The structure modifications we received were aimed at increasing the biodegradation of the drug used. The influence of the alkyl chain length of the ester used in the biodegradation of the compound was also verified. The biodegradation results correlated with the lipophilic properties (log P).     

Corrosion Behavior in Magnesium-Based Alloys for Biomedical Applications

Magnesium alloys exhibit superior biocompatibility and biodegradability, which makes them an excellent candidate for artificial implants. However, these materials also suffer from lower corrosion resistance, which limits their clinical applicability. The corrosion mechanism of Mg alloys is complicated since the spontaneous occurrence is determined by means of loss of aspects, e.g., the basic feature of materials and various corrosive environments. As such, this study provides a review of the general degradation/precipitation process multifactorial corrosion behavior and proposes a reasonable method for modeling and preventing corrosion in metals. In addition, the composition design, the structural treatment, and the surface processing technique are involved as potential methods to control the degradation rate and improve the biological properties of Mg alloys. This systematic representation of corrosive mechanisms and the comprehensive discussion of various technologies for applications could lead to improved designs for Mg-based biomedical devices in the future.     

新型生物可吸收房间隔缺损封堵器的生物相容性研究

目的评价自主研究的新型房间隔封堵器的生物相容性,为动物实验提供依据。方法封堵器框架由生物可吸收聚左旋乳酸(poly-L-lactic acid,PLLA)单丝网编织成型。通过对PLLA单丝进行体外细胞毒性测试、体外溶血测试、全身急性毒性测试、肌肉植入实验,评价新型房间隔封堵器的生物相容性。结果 PLLA房间隔缺损封堵器无体外细胞毒性,体外溶血率0.9%,无急性全身毒性反应。通过分析样品植入肌肉1个月、3个月和6个月后组织病理,观察样品与组织之间的反应,未发现明显的组织损伤和组织增生。结论生物可吸收PLLA房间隔封堵器的生物相容性良好,可进行下一步的动物实验研究。