Astaxanthin and its Effects in Inflammatory Responses and Inflammation-Associated Diseases: Recent Advances and Future Directions

Astaxanthin is a natural lipid-soluble and red-orange carotenoid. Due to its strong antioxidant property, anti-inflammatory, anti-apoptotic, and immune modulation, astaxanthin has gained growing interest as a multi-target pharmacological agent against various diseases. In the current review, the anti-inflammation mechanisms of astaxanthin involved in targeting for inflammatory biomarkers and multiple signaling pathways, including PI3K/AKT, Nrf2, NF-κB, ERK1/2, JNK, p38 MAPK, and JAK-2/STAT-3, have been described. Furthermore, the applications of anti-inflammatory effects of astaxanthin in neurological diseases, diabetes, gastrointestinal diseases, hepatic and renal diseases, eye and skin disorders, are highlighted. In addition to the protective effects of astaxanthin in various chronic and acute diseases, we also summarize recent advances for the inconsistent roles of astaxanthin in infectious diseases, and give our view that the exact function of astaxanthin in response to different pathogen infection and the potential protective effects of astaxanthin in viral infectious diseases should be important research directions in the future.     

Preparation of Antioxidant Protein Hydrolysates from Pleurotus geesteranus and Their Protective Effects on H2O2 Oxidative Damaged PC12 Cells

Pleurotus geesteranus is a promising source of bioactive compounds. However, knowledge of the antioxidant behaviors of P. geesteranus protein hydrolysates (PGPHs) is limited. In this study, PGPHs were prepared with papain, alcalase, flavourzyme, pepsin, and pancreatin, respectively. The antioxidant properties and cytoprotective effects against oxidative stress of PGPHs were investigated using different chemical assays and H₂O₂ damaged PC12 cells, respectively. The results showed that PGPHs exhibited superior antioxidant activity. Especially, hydrolysate generated by alcalase displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (91.62%), 2,2-azino-bis (3-ethylbenzothia zoline-6-sulfonic acid) (ABTS) radical scavenging activity (90.53%), ferric reducing antioxidant power, and metal ion-chelating activity (82.16%). Analysis of amino acid composition revealed that this hydrolysate was rich in hydrophobic, negatively charged, and aromatic amino acids, contributing to its superior antioxidant properties. Additionally, alcalase hydrolysate showed cytoprotective effects on H₂O₂-induced oxidative stress in PC12 cells via diminishing intracellular reactive oxygen species (ROS) accumulation by stimulating antioxidant enzyme activities. Taken together, alcalase hydrolysate of P. geesteranus protein can be used as beneficial ingredients with antioxidant properties and protective effects against ROS-mediated oxidative stress.     

Development of a solid‐phase microextraction LC–MS/MS method for determination of oxidative stress biomarkers in biofluids

Recently the connection between oxidative stress and various diseases, including cancer and Alzheimer's, attracts notice as a pathway suitable for diagnostic purposes. 8‐Oxo‐deoxyguanosine and 8‐oxo‐deoxyadenosine produced from the interaction of reactive oxygen species with DNA become prominent as biomarkers. Several methods have been developed for their determination in biofluids, including solid‐phase extraction and enzyme‐linked immunosorbent assays. However, still, there is a need for reliable and fast analytical methods. In this context, solid‐phase microextraction offers many advantages such as flexibility in geometry and applicable sample volume, as well as high adaptability to high‐throughput sampling. In this study, a solid‐phase microextraction method was developed for the determination of 8‐oxo‐deoxyguanosine and 8‐oxo‐deoxyadenosine in biofluids. The extractive phase of solid‐phase microextraction consisted of hydrophilic–lipophilic balanced polymeric particles. In order to develop a solid‐phase microextraction method suitable for the determination of the analytes in saliva and urine, several parameters, including desorption solvent, desorption time, sample pH, and ionic strength, were scrutinized. Analytical figures of merit indicated that the developed method provides reasonable interday and intraday precisions (<15% in both biofluids) with acceptable accuracy. The method provides a limit of quantification for both biomarkers at 5.0 and 10.0 ng/mL levels in saliva and urine matrices, respectively.     

Injectable Enzyme‐Based Hydrogel Matrix with Precisely Oxidative Stress Defense for Promoting Dermal Repair of Burn Wound

Burn wound healing remains a challenging health problem worldwide due to the lack of efficient and precise therapy. Inherent oxidative stress following burn injury is importantly responsible for prolonged inflammation, fibrotic scar, and multiple organ failure. Herein, a bioinspired antioxidative defense system coupling with in situ forming hydrogel, namely, multiresponsive injectable catechol‐Fe³⁺ coordination hydrogel (MICH) matrix, is engineered to promote burn‐wound dermal repair by inhibiting tissue oxidative stress. This MICH matrix serves as the special traits of “Fe‐superoxide dismutases,” small molecular antioxidant (vitamin E), and extracellular matrix (ECM) in alleviating cellular oxidative damage, which demonstrates precise scavenging on reactive oxygen species (ROS) of different cellular locations, blocking lipid peroxidation and cell apoptosis. In in vivo burn‐wound treatment, this MICH promptly integrates with injured surrounding tissue to provide hydration microenvironment and physicochemical ECM for burn wounds. Importantly, the MICH matrix suppresses tissue ROS production, reducing the inflammatory response, prompting re‐epithelization and neoangiogenesis during wound healing. Meanwhile, the remodeling skin treated with MICH matrix demonstrates low collagen deposition and normal dermal collagen architecture. Overall, the MICH prevents burn wound progression and enhances skin regeneration, which might be a promising biomaterial for burn‐wound care and other disease therapy induced by oxidative stress.     

Doping Polysulfone Membrane with Alpha‐Tocopherol and Alpha‐Lipoic Acid for Suppressing Oxidative Stress Induced by Hemodialysis Treatment

The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress‐associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α‐lipoic acid, α‐tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid‐peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation.     

杆件在横向力和轴向压力共同作用下的内力计算

针对杆件在横向力和轴向压力共同作用下的内力计算问题进行了研究．在考虑杆件变形因素的情形下,推导出了杆件在横向力和轴向压力共同作用下的内力和正应力的计算公式,并与材料力学中未考虑杆件变形因素的对应公式进行了比较,说明了二者之间不同之处．     

循环加载作用下皮肤应力软化的连续介质模型

皮肤组织作为富含纤维的非均匀材料,具有复杂的力学特性．皮肤组织在循环加载作用下,随着循环次数的增加,加载过程的应力响应逐渐降低,并最终达到不随循环次数增加而改变的稳定状态,这种现象被称为应力软化行为．本文对加载过程中纤维的延展机制对宏观力学响应的影响进行研究,认为在外界载荷较小时该机制主导了宏观层次上的应力软化行为,随着外界载荷的增大,拉伸过程中微观结构损伤的演化开始产生影响,而且此时内部微观结构的演化由两种机制共同影响,据此建立了连续介质模型,将宏观尺度上应力软化行为和微观结构的演化相关联．将所获得的应力响应理论结果与猪离体头部皮肤在循环加载作用下的实验结果进行对比分析,证明了该模型能够合理地描述皮肤组织在循环加载作用下的应力软化行为．     

纤维增强金属基复合材料整体蠕变性能的细观力学分析

高温下金属基复合材料的蠕变主要由基体蠕变和界面扩散蠕变两部分构成,以往的研究中常常只考虑其中一种蠕变机理,从而导致得到的规律具有较大的局限性．本文提出了一种可预测金属基复合材料整体蠕变性能的细观力学方法,同时考虑了基体蠕变和界面扩散蠕变两种蠕变机理,导出了具有张量形式并满足不可压缩性的界面扩散蠕变应变表达式．采用Mori-Tanaka法和自洽法二者结果的平均以便更准确地计算纤维中的应力,揭示了两种蠕变机理相互影响的竞争关系．研究了恒定双轴荷载下的总体蠕变和固定位移约束下的应力松弛这两种常见蠕变问题,探究了基体蠕变与界面扩散蠕变两种蠕变机理在总蠕变中发挥的作用,考察了不同加载条件和不同纤维体积分数对复合材料整体蠕变行为的影响．     

高韧性合金钢断裂韧性及疲劳裂纹扩展门槛值的联合试验方法

在柴油机曲轴、连杆等关键零部件的可靠性设计和失效评估中,断裂韧性及疲劳裂纹扩展门槛值分别是衡量材料抵抗裂纹失稳扩展和裂纹开始扩展的重要指标．但是,对于高韧性合金材料,难以通过常规试验所推荐的厚度确定平面应变断裂韧性,而门槛值的测定通常不但非常耗时,且难以直接应用于不同循环特性的实际结构．本文针对高韧性合金钢34CrNi3MoA,提出一种将断裂韧性和疲劳裂纹扩展门槛值试验合二为一的试验方法,即用同一个试件可以同时测定门槛值和断裂韧性．利用断裂韧性关于试件厚度的渐近特性,以几种较薄试件的试验,确定平面应变状态下的断裂韧性．试验结果还表明,裂纹扩展门槛值的试件厚度依存性可以忽略,并给出了任意循环特性（应力比）下的门槛值计算公式．