Hydroxypropyl chitosan(HP-chitosan) has been shown to have promising applications in a wide range of areas due to its biocompatibility, biodegradability and various biological activities, especially in the biomedical and pharmaceutical fields. However, it is not yet known about its pharmacokinetics and biodegradation performance, which are crucial for its clinical applications. In order to lay a foundation for its further applications and exploitations, here we carried out fluorescence intensity and GPC analyses to determine the pharmacokinetics mode of fluorescein isothiocyanate-labeled HP-chitosan(FITC-HP-chitosan) and its biodegradability. The results showed that after intraperitoneal administration at a dose of 10 mg per rat, FITC-HP-chitosan could be absorbed rapidly and distributed to liver, kidney and spleen through blood. It was indicated that FITC-HP-chitosan could be utilized effectively, and 88.47% of the FITC-HP-chitosan could be excreted by urine within 11 days with a molecular weight less than 10 k Da. Moreover, our data indicated that there was an obvious degradation process occurred in liver(< 10 k Da at 24 h). In summary, HP-chitosan has excellent bioavailability and biodegradability, suggesting the potential applications of hydroxypropyl-modified chitosan as materials in drug delivery, tissue engineering and biomedical area.
Transcription factor NF-κB has attracted attention due to its important role in the regulation of the expression of a number of cellular genes involved in host defense,inflammation/immune responses,cytokine and growth factor regulation,cell survival,proliferation,and also in embryonic development and programmed cell death. In this review,we provide an overview of established TNF-α,TLR/IL-1R,TCR and BCR signaling pathways to NF-κB,the alternative NF-κB pathway,and the regulation of NF-κB transcriptional activity. Furthermore,we discuss on emphasis the cross-talks between NF-κB and other signaling pathways (TGF-β,p53,nuclear receptor family,Ras/MEK/MAPK...),which are very complex and remain to be understood. The activation or inhibition of NF-κB has effect on other signaling pathways. They compose a complex signaling network,in which many regulatory signals integrate systematically and coordinate transcriptional responses to the stimulations. So when NF-κB is used as an important target of drugs in human diseases,the pathological and physiological functions of related signal pathways also should be understood sufficiently.
采用Discover微波精确有机合成系统及其单模聚焦微波辐射技术与空压气体同步冷却技术,分别以脂肪酶和辛酸亚锡为催化剂,聚乙二醇(PEG)为大分子引发剂引发消旋丙交酯(D,L-LA)开环聚合制备PLA-PEG-PLA共聚物,通过正交实验研究了功率、催化剂种类和用量、时间和温度对共聚物产率的影响,确定了最佳合成条件。在此基础上,改变n(D,L-LA)/n(PEG)投料比制备了不同组成的PLA-PEG-PLA共聚物,采用IR、1 H NMR、GPC和表面接触角测定对共聚物进行了表征。结果表明,在微波作用下,两种催化剂均可催化体系反应得到共聚物,但脂肪酶的催化效率较低,对应共聚物的分子量不高;原料配比对共聚物的组成与性能有显著影响,随n(D,L-LA)/n(PEG)值增大,共聚物的分子量增大;由于引入了亲水性的聚乙二醇链段,共聚物的亲水性明显优于单一的PLA材料。
