Time Interval of Two Injections and First-Dose Dependent of Accelerated Blood Clearance Phenomenon Induced by PEGylated Liposomal Gambogenic Acid: The Contribution of PEG-Specific IgM

Repeated injection of PEGylated liposomes can cause the disappearance of long circulating property because of the induction of anti-PEG IgM antibody referred to as “accelerated blood clearance (ABC) phenomenon.” Although ABC phenomenon typically occurs when entrapped drugs are chemotherapeutic agent with low cytotoxic, there is little evidence of accelerated blood clearance of PEGylated herbal-derived compound on repeated injection. Herein, we investigated the blood concentration of PEGylated liposomal gambogenic acid (PEG-GEA-L), a model PEGylated liposomal herbal extract, on its repeated injection to rats. We found time interval between injections had considerable impact on the magnitude of ABC phenomenon induced by PEG-GEA-L. When time interval was prolonged from 3 days to 7 days, ABC phenomenon could be attenuated. Furthermore, its magnitude was enhanced accompanied by a marked rise in the accumulation of PEG-GEA-L in the liver and spleen in a first-dose–dependent manner. Consistently, the level of anti-PEG IgM significantly increased with the first dose of PEG-GEA-L and decreased with the extended time interval between injections, which implies anti-PEG IgM is a major contributor to the ABC phenomenon. Notably, the increased expression of liver anti-PEG IgM was accompanied by an increased expression of efflux transporters in the induction process of the ABC phenomenon.     

Quantitative Prediction of Oral Bioavailability of a Lipophilic Antineoplastic Drug Bexarotene Administered in Lipidic Formulation Using a Combined In Vitro Lipolysis/Microsomal Metabolism Approach

For performance assessment of the lipid-based drug delivery systems (LBDDSs), in vitro lipolysis is commonly applied because traditional dissolution tests do not reflect the complicated in vivo micellar formation and solubilization processes. Much of previous research on in vitro lipolysis has mostly focused on rank-ordering formulations for their predicted performances. In this study, we have incorporated in vitro lipolysis with microsomal stability to quantitatively predict the oral bioavailability of a lipophilic antineoplastic drug bexarotene (BEX) administered in LBDDS. Two types of LBDDS were applied: lipid solution and lipid suspension. The predicted oral bioavailability values of BEX from linking in vitro lipolysis with microsomal stability for lipid solution and lipid suspension were 34.2 ± 1.6% and 36.2 ± 2.6%, respectively, whereas the in vivo oral bioavailability of BEX was tested as 31.5 ± 13.4% and 31.4 ± 5.2%, respectively. The predicted oral bioavailability corresponded well with the oral bioavailability for both formulations, demonstrating that the combination of in vitro lipolysis and microsomal stability can quantitatively predict oral bioavailability of BEX. In vivo intestinal lymphatic uptake was also assessed for the formulations and resulted in <1% of the dose, which confirmed that liver microsomal stability was necessary for correct prediction of the bioavailability.     

OVA-bound nanoparticles induce OVA-specific IgG1, IgG2a,and IgG2b responses with low IgE synthesis

There is an urgent requirement for a novel vaccine that can stimulate immune responses without unwanted toxicity, including IgE elevation. We examined whether antigen ovalbumin (OVA) conjugated to the surface of nanoparticles (NPs) (OVA-NPs) with average diameter of 110 nm would serve as an immune adjuvant. When BALB/c mice were immunized with OVA-NPs, they developed sufficient levels of OVA-specific IgG1 antibody responses with low levels of IgE synthesis, representing helper T (Th)2-mediated humoral immunity. OVA-specific IgG2a and IgG2b responses (i.e., Th1-mediated immunity) were also induced by secondary immunization with OVA-NPs. As expected, immunization with OVA in alum (OVA-alum) stimulated humoral immune responses, including IgG1 and IgE antibodies, with only low levels of IgG2a/IgG2b antibodies. CD4-positive T cells from mice primed with OVA-NPs produced substantial levels of IL-21 and IL-4, comparable to those from OVA-alum group. The irradiated mice receiving OVA-NPs-primed B cells together with OVA-alum-primed T cells exhibited enhanced anti-OVA IgG2b responses relative to OVA-alum-primed B cells and T cells following stimulation with OVA-NPs. Moreover, when OVA-NPs-primed, but not OVA-alum-primed, B cells were cultured in the presence of anti-CD40 monoclonal antibody, IL-4, and IL-21, or LPS plus TGF-β in vitro, OVA-specific IgG1 or IgG2b antibody responses were elicited, suggesting that immunization with OVA-NPs modulates B cells to generate IgG1 and IgG2b responses. Thus, OVA-NPs might exert their adjuvant action on B cells, and they represent a promising potential vaccine for generating both IgG1 and IgG2a/IgG2b antibody responses with low IgE synthesis.     

下颈椎前路椎弓根螺钉固定系统与普通前路椎体螺钉固定系统的静力学比较

目的：比较下颈椎前路椎弓根螺钉（ATPS）锁定固定系统和普通前路椎体螺钉（VBS）锁定固定系统的静力学特性。方法：采集新鲜颈椎标本16具,分解为C3.,4,C4,5,C5,6,C6,7共32个运动节段（functionalspinalunit,FSU）,其中C3,4,C4,5,C5,6,C6,7各8个。将其按照不同节段随机分成A、B两组,对所获标本椎间盘切除后模拟植骨,分别植入自行设计生产的下颈椎前路椎弓根螺钉配套钢板系统和普通颈椎前路椎体螺钉钢板系统。在生物力学试验机上行钢板的垂直拔出强度试验。结果：下颈椎前路椎弓根螺钉的最大轴向拔出力为（604．68±48．76）N,椎体螺钉为（488．24±32．42）N,两者比较差异有统计学意义（t=2．147,P〈0．05）,前路椎弓根螺钉固定系统与椎体螺钉固定系统在各FSU间差异无统计学意义（A组和B组的F值分别为2．27、2．05,P〉0．05）。结论：下颈椎前路椎弓根螺钉钢板系统的拔出力明显优于普通前路椎体螺钉钢板系统,从生物力学角度上来看具有应用可行性。     

表面处理及不同水门汀材料对纤维桩粘固性能影响的研究

目的：评价酸蚀一喷砂处理以及4种不同水门汀材料Fuji I（FUI）、Fuji Cem（FUC）、RelyX Unicem（RX—U）、RelyXARC（RXA））对纤维桩粘固性能的影响。方法：选取80颗无龋坏单根管人前磨牙,根据对应纤维桩表面处理与否随机分为2组,进而根据粘接材料的不同分为4个亚组。常规根管充填和桩道预备后,分别选用4种水门汀材料将表面处理前后的玻璃纤维桩粘接到预备根管内;观察纤维桩表面及每组试件粘接界面扫描电镜（SEM）下微观形貌,测试即刻拉出强度（pull—outtest）。结果：表面处理前后纤维桩的各水门汀材料拉出强度以RXA组最高,随后依次为RXU、FUC、FUI组,且各组间均相差显著（P〈0．05）;纤维桩表面处理后与各水门汀材料的拉出强度较之处理前均显著提高（P〈0．05）：SEM观察显示：表面处理后纤维桩的表面粗糙度纤维暴露数量均有明显增加;表面处理前后各组粘接界面微观形貌存在差异,各组的粘接界面均较处理前更致密。结论：酸蚀一喷砂处理纤维桩表面后可以提高其与不同水门汀材料的粘接固位力。     

Probing the weak interaction of proteins with neutral and zwitterionic antifouling polymers

Protein–polymer interactions are of great interest in a wide range of scientific and technological applications. Neutral poly(ethylene glycol) (PEG) and zwitterionic poly(sulfobetaine methacrylate) (pSBMA) are two well-known nonfouling materials that exhibit strong surface resistance to proteins. However, it still remains unclear or unexplored how PEG and pSBMA interact with proteins in solution. In this work, we examine the interactions between two model proteins (bovine serum albumin and lysozyme) and two typical antifouling polymers of PEG and pSBMA in aqueous solution using fluorescence spectroscopy, atomic force microscopy and nuclear magnetic resonance. The effect of protein:polymer mass ratios on the interactions is also examined. Collective data clearly demonstrate the existence of weak hydrophobic interactions between PEG and proteins, while there are no detectable interactions between pSBMA and proteins. The elimination of protein interaction with pSBMA could be due to an enhanced surface hydration of zwitterionic groups in pSBMA. New evidence is given to demonstrate the interactions between PEG and proteins, which are often neglected in the literature because the PEG–protein interactions are weak and reversible, as well as the structural change caused by hydrophobic interaction. This work provides a better fundamental understanding of the intrinsic structure–activity relationship of polymers underlying polymer–protein interactions, which are important for designing new biomaterials for biosensor, medical diagnostics and drug delivery applications.     

Spatiotemporal tracking of cells in tissue‐engineered cardiac organoids

Cardiac tissue engineering aims to create myocardial patches for repair of defective or damaged native heart muscle. The inclusion of non‐myocytes in engineered cardiac tissues has been shown to improve the properties of cardiac tissue compared to tissues engineered from enriched populations of myocytes alone. While attempts have been made to mix non‐myocytes (fibroblasts, endothelial cells) with cardiomyocytes, very little is understood about how the tissue properties are affected by varying the respective ratios of the three cell types and how these cells assemble into functional tissues with time. The goal of this study was to investigate the effects of modulating the ratios of the three cell types and to spatially and temporally track cardiac tri‐cultures of cells. Primary neonatal cardiac fibroblasts and D4T endothelial cells were incubated in 5 µM CellTracker^? green dye and CellTracker^? red dye, respectively, while neonatal cardiomyocytes were labelled with 20 µg/mL DAPI. The non‐myocytes were seeded either sequentially (pre‐culture) or simultaneously (tri‐culture) in Matrigel‐coated microchannels and allowed to form organoids, as in our previous studies. We also varied the seeding percentage of cardiomyocytes while keeping the total cell number constant in an attempt to improve the functional properties of the organoids. Organoids were imaged on days 1 and 4. Endothelial cells were seen to aggregate into clusters when simultaneously tri‐cultured with myocytes and fibroblasts, while pre‐cultures contained elongated cells. Functional properties of organoids were improved by increasing the seeding percentage of enriched cardiomyocytes from 40% to 80%. Copyright © 2009 John Wiley & Sons, Ltd.     

Individualizing treatment duration in hepatitis C virus genotype 2/3‐infected patients

The drugs currently licensed for the treatment of hepatitis C are Peg‐Interferon (PEG‐IFN) and ribavirin. In recent years, the recommendation to treat hepatitis C virus genotype 2‐ and 3‐infected patients with a fixed 800 mg/day dose of ribavirin in combination with PEG‐IFN and for just 24 weeks has been challenged by the concept of tailoring the length of therapy according to on‐treatment viral response. Therefore, the objective of the present review was to highlight the different designs of the studies on short treatment duration and the role of wk4‐R as a predictor of sustained virological response after an abbreviated course of treatment. The secondary aim was to verify whether we had enough evidence to support the implementation of a short treatment course in subsets of patients with genotype 2 and 3 infection. We will also focus on how drug dosing may have influenced the outcome of treatment. To clarify reasons for discrepant results in the studies so far published, the recently discovered genetic variant near the interleukin 28B gene will be presented and its predictive role will be discussed. Finally, we will face the debated issue of whether the subset of patients with genotype 2 or 3 requires an extended treatment duration.