抗氧化功能乳酸菌的筛选、作用机理及其提高蔬菜抗氧化性的研究进展

乳酸菌及其产生的发酵剂具有较大的抗氧化作用，而大多数生命有机体必需进行生物氧化，但是氧化代谢产生的自由基会损害细胞和组织，因此作为益生菌的乳酸菌是开发天然抗氧化剂的重要资源。具有抗氧化功能的乳酸菌的筛选情况、乳酸菌产生抗氧化物质的作用机理有待进一步研究，且利用抗氧化活性乳酸菌提高蔬菜的抗氧化性和安全性也成为了研究的热点。文章概述了抗氧化功能乳酸菌的筛选工作，综述了其作用机理，阐述了提高蔬菜抗氧化功能的研究进展，展望了该研究的未来发展情况。     

乳酸菌的抗氧化作用机制

乳酸菌可以作为发酵剂、保鲜剂用于发酵食品的生产和保藏。由于无法进行呼吸产能,乳酸菌在生长过程中会面临氧化胁迫。研究表明,乳酸菌具有一定的抗氧化能力,能清除体内的活性氧分子,并使其保持相对稳定。综述了乳酸菌的抗氧化作用机制,主要从抗氧化酶、维持细胞还原状态、金属离子螯合等方面进行了介绍,以期为深入了解乳酸菌的抗氧化机制以及改善乳酸菌的环境生存能力提供一定的理论参考。     

乳酸菌抗氧化活性及其应用研究进展

乳酸菌作为一种天然的抗氧化剂，其抗氧化特性一直是研究热点之一。绝大多数乳酸菌为厌氧菌或兼性厌氧菌，一般适合生长于无氧或含氧量低的环境中，部分乳酸菌菌株由于自身含有高活性的抗氧化酶及氧化还原系统而具有良好的抗氧化特性。作为一种常见的发酵微生物，乳酸菌在食品生产中不仅具有改善风味的作用，其抗氧化作用对于延长食品的保藏期具有重要意义。同样，机体的氧化应激与许多生理、病理现象密切相关，大量研究已经证实乳酸菌在缓解相关疾病方面具有益生功能。本文对乳酸菌的氧化胁迫及其应答和防御机制、提高乳酸菌抗氧化活性的技术方法及应用进行综述，旨在为深入了解乳酸菌的抗氧化机制以及开发具有良好抗氧化活性的菌株提供理论参考。     

风干羊肉中乳酸菌的体内外抗氧化特性

【背景】机体的衰老和一些疾病多与氧化作用有关,随着对抗氧化制剂研究的深入,人工合成抗氧化剂的安全性受到质疑,因此寻找天然抗氧化制剂的研究已成为热点。【目的】从风干羊肉中筛选抗氧化活性较高的乳酸菌,分析肉源乳酸菌体内外抗氧化能力。【方法】以24株肉源乳酸菌为研究对象,以自由基清除能力、亚铁离子螯合能力、还原能力及抗脂质过氧化能力为体外抗氧化能力分析指标,筛选出体外抗氧化活性较强的乳酸菌,运用16S rRNA基因序列同源性分析进行菌种鉴定,通过小鼠试验研究其体内抗氧化能力。【结果】试验所测24株乳酸菌均具有一定的体外抗氧化能力,其中菌株TR13为24株乳酸菌中体外抗氧化能力较强的菌株,其超氧阴离子自由基(·O2?)清除率为54.29%,羟自由基(·OH)清除率为90.84%,1,1-二苯基-2-三硝基苯肼自由基(1,1-diphenyl-2-picrylhydrazyl,DPPH)清除率为99.38%,亚铁离子螯合率为55.85%,还原能力达1.345,抗脂质过氧化率为39.99%。通过16S rRNA基因鉴定,菌株TR13为一株瑞士乳杆菌。通过给D-半乳糖诱导的衰老型小鼠饲喂TR13菌液,验证了TR13对小鼠的肝脏、肾脏及血液组织中谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性、超氧化物歧化酶(superoxide dismutase,SOD)活性、过氧化氢酶(catalase,CAT)活性均有显著的提升作用(p<0.05),且TR13组的GSH-Px活性显著高于维生素C (Vc)组(p<0.05)。【结论】菌株TR13对机体的氧化具有一定的防御作用,研究结果可为乳酸菌抗氧化制剂的研究提供参考依据。     

抗氧化乳酸菌在体外结肠环境清除羟自由基的研究

目的利用鼠肝匀浆经Fe^2＋ -VitC诱导产生丙二醛（MDA）为模型研究29株乳酸菌的抗氧化活性。方法建立体外模拟结肠发酵体系,分析3株具有不同抗氧化能力的乳酸菌（Lactobacillus paracasei Fn032,Laaobacillus rhamnosus GG,Lactobacillus sp．Fn001）在正常结肠和铁过载结肠模型中清除羟自由基效果及对肠球菌增殖的的影响,并检测3株菌螯合亚铁离子能力及其无细胞提取物超氧化物歧化酶（SOD）活性。结果体外结肠体系中羟自由基含量与肠球菌数量有显著相关性。在正常结肠环境中,3株乳酸菌清除羟自由基能力与其SOD活性一致,但与其抑制肠球菌增殖能力和螯合亚铁离子能力不一致。在高铁结肠环境中,3株乳酸菌清除羟自由基能力与它们抑制肠球菌增殖能力和螯合亚铁离子能力一致,但与SOD活性不一致。结论正常条件下乳酸菌可通过产生抗氧化酶来清除结肠自由基,铁过载条件则可增强具有铁螯和能力乳酸菌的抗氧化活性。     

具高抗氧化能力乳酸菌菌株的筛选与鉴定

目的筛选抗氧化能力强的乳酸菌菌株并进行菌种鉴定。方法通过清除DPPH自由基、清除超氧阴离子自由基、还原能力等实验,筛选出高抗氧化能力的乳酸菌菌株。运用16SrDNA序列分析方法,对抗氧化能力强的菌株进行鉴定。结果本研究筛选得到的抗氧化能力较强的菌株有长双歧杆菌NQ1501、La8、La5和保加利亚乳杆菌NQ2508,经16SrDNA鉴定和系统进化分析,La5鉴定为发酵乳杆菌(Lactobacillus fermentum),La8鉴定为鼠李糖乳杆菌(Lactobacillus rhamnosus)。结论本研究筛选出四株具有高抗氧化活性的乳酸菌,分别为长双歧杆菌NQ1501、鼠李糖乳杆菌La8、发酵乳杆菌La5和保加利亚乳杆菌NQ2508。     

阿克苏地区传统酸乳中乳酸菌筛选及安全性初步评价

为挖掘新疆传统发酵乳制品中的优质乳酸菌资源,获得具有良好益生特性及食用安全性的乳酸菌菌株,对新疆阿克苏地区托木尔峰自然保护区周围村镇传统酸乳进行了样品采集、乳酸菌的分离、筛选及菌株生长特性、抗氧化活性和抑菌等功能特性的分析,并进行溶血性和有害代谢物质等食用安全性检测.16S rRNA测序结果显示,8份代表样品共获得12...     

乳酸菌发酵中药功能及其增效机制的研究进展

发酵中药制备中结合使用乳酸菌菌种，不仅能增加中药类型的丰富度，还能摸索出中药更多的新功能，引领中药产业的创新发展。文章简单概述乳酸菌发酵的基本原理，阐明乳酸菌发酵中药的优势，探究其具备的药理学功能，包括棉衣调控、抗氧化、减轻胃肠道炎症等，并从中药成分释放、转化、增菌功用等方面探究乳酸菌类发酵中药涉及的药效提升机制，希望进一步提升同行对乳酸菌发酵中药产品的认知。     

乳酸菌抑制葡聚糖硫酸钠诱导的结肠黏膜氧化应激损伤的研究

目的研究乳酸菌抗氧化活性与缓解葡聚糖硫酸钠(DSS)诱导结肠炎的关系。方法评价5株乳酸菌体外抑制大鼠肝细胞脂质过氧化活性,用DSS诱导小鼠结肠炎模型研究抗氧化性不同的菌株体内抗氧化活性;小鼠分成7组,分别是Control组、DSS组、L.plantarum Fn008+DSS组、L.casei Fn012+DSS组、L.acidophilus Fn022+DSS组、L.sakei Fn034+DSS组和L.acidophilus Fn037+DSS组。结果体外实验表明,Fn022和Fn034的丙二醛(MDA)抑制率高于LGG,但差异无统计学意义,Fn008和Fn037的MDA抑制率显著低于LGG,Fn012的MDA抑制率最低。体内实验表明,DSS可导致小鼠氧化应激,升高结肠内容物的自由基水平,降低结肠抗氧化能力;Fn008和Fn037预处理能显著降低DSS诱导结肠内容物的自由基水平,Fn008能显著降低结肠组织的髓过氧化物酶(MPO)水平,提高结肠抗氧化能力,Fn022和Fn034的干预能力居中,Fn012的干预能力最弱。相关性分析表明乳酸菌体外MDA清除率与体内MPO有负相关趋势(r=-0.862,P=0.06)。结论乳酸菌抗氧化活性与其在肠道抑制炎性细胞激活的作用有关,本实验中Fn008和Fn037具有显著的体内抗氧化作用。     

猪消化道中产苯乳酸乳酸菌的益生特性研究

【目的】建立一种简单有效的产苯乳酸乳酸菌的筛选方法,并筛选到高产苯乳酸的乳酸菌。【方法】菌株经过添加了苯丙氨酸的培养基厌氧培养后,利用高效液相色谱法检测发酵液中苯乳酸的含量。【结果】从猪的消化道中共分离得到31株产苯乳酸的乳酸菌,其中菌株R53的苯乳酸产量最大,为321.7 mg/L。菌株R53对.OH、O2和DPPH都有清除能力,清除率分别达到11.2%、52.7%和63.2%。同时R53也能降低培养基中胆固醇的含量,清除率为32.5%。【结论】乳酸菌R53经菌落形态、细胞形态、生化反应实验、16S rDNA测序,最终确定为植物乳杆菌。植物乳杆菌R53能产生苯乳酸,具有清除胆固醇和抗氧化能力。     

On the compartmentalization of catalase,fatty acyl-CoA oxidase and urate oxidase in mammalian livers,and the influence of clofibrate treatment on this microlocalization

The compartmentalization of catalase, fatty acyl-CoA oxidase and urate oxidase was examined in the livers of mice, rats and guinea pigs, using the technique of digitonin extraction in order to avoid the trauma associated with centrifugation procedures. The results are interpreted as indicating that an appreciable proportion of catalase activity occurs in the cytoplasmic compartment of these cells. Following treatment of the animals with clofibrate, the specific activity in both peroxisomal and cytoplasmic compartments was increased, with a higher proportion of cytoplasmic catalase being evident in mice. The results for catalase were compared with those for fatty acyl-CoA oxidase and urate oxidase both of which were indicated as showing a closer association with the peroxisomal compartment than was the case for catalase. These data have been discussed in relation to their significance on present understanding of peroxisomal structure and function.     

自噬在肝再生中的作用

自噬是存在于真核细胞内的一种溶酶体依赖性的降解途径,在肝脏生理和病理过程中发挥着重要作用。肝脏具有强大的再生能力,在受到急、慢性损伤时,残肝细胞将会被激活进入细胞周期进行细胞增殖,以补偿丢失的肝组织和恢复肝功能。文章阐述了各种类型损伤之后的肝再生与自噬的关系。在物理性、酒精、食源性等因素引起的肝损伤中,肝脏通过启动自噬来促进肝再生;在化学性损伤的肝再生模型中,自噬在其中的作用仍然有争议;在病毒感染之后的肝再生中,一些嗜肝病毒（如丙肝病毒和乙肝病毒等）反而利用自噬来促进病毒颗粒复制,抑制肝再生。对自噬和肝再生机制的研究,将有助于进一步阐明再生过程,为治疗肝脏疾病提供新方法。     

Is the ATP — dependent protection of lysosomes against osmotic lysis a function of the lysosomal proton pump

Summary Rat liver lysosomes have been used to characterize further the effects of ATP on lysosomal stability during incubation at 37°C at hypo-osmolarity. As previously reported, when the osmotically-supporting solute is the salt of a strong base (K⁺), ATP protects against lysis during incubation. However, if the osmotically-supporting solute is the salt of a weak base, e.g. Tris HCl or NH₄Cl, ATP actually promotes lysis during incubation. Thus, ATP can exert destabilizing as well as protective effects on lysosomes. The destabilizing effect is eliminated by protonophores. The protective effect in the presence of potassium salts is not eliminated by protonophores. Moreover, when incubation is in the presence of a salt of a weak base, protonophores actually cause an ATP-dependent protective effect to be established. The destabilizing effect occurs at 37°C, but not at 0°C. The Mg^–+-dependence of the destabilizing effect was found to be similar to that found earlier for the ATP-dependent protective effect, insofar as only 1 mM MgCl₂ in the presence of 1 mM EDTA is sufficient for nearly maximal stimulation of both effects. The destabilizing effect may result from a H^– ion gradient across the lysosomal membrane which is maintained by the lysosomal ATP-dependent proton pump. The protective effect, on the other hand, does not depend on such a gradient being maintained; on the contrary, protonophores appear to act as enablers of the protective effect. The question that remains to be answered is: does the protective effect derive in some way from the same ATP-driven mechanism which constitutes the proton pump? Some possible answers to this question are considered.Abbreviations Mops 2-(N-morpholine)-propanesulfonic acid - CCCP Carbonyl cyanide m-chlorophenylhydrazone - DNP 2,4-Dinitrophenol - EDTA Ethylenediaminetetracetic acid     

Isolated hepatocytes in a bioartificial liver: A single group view and experience

Despite recent advances in medical supportive therapy, patients with severe fulminant hepatic failure (FHF) have mortality rate approaching 90%. Investigators have attempted to improve survival by using various extracorporeal liver support systems loaded with sorbents and liver tissue preparations. None of them succeeded in gaining clinical acceptance and orthotopic liver transplantation (OLT) remains a primary therapeutic option for patients with FHF. In this study, authors discuss the systems which utilize isolated hepatocytes. Most of these devices were tested in vitro and in animals with chemically and surgically induced liver failure. In some studies, signficant levels of detoxification and liver functions were achieved. The authors describe their own hepatocyte-based artificial liver (BAL). It is based on plasma perfusion through a hollow-fiber module seeded with matrix-anchored porcine hepatocytes. The BAL was used 14 times to treat 9 patients with acute liver failure. On 10 occasions, a charcoal column was included in the plasma circuit. Each treatment lasted 7 +/- 1 h. All procedures were tolerated well and 8 patients (including 6 patients with FHF) underwent OLT. Five patients with increased intracranial pressure (ICP) and evidence of decerebration had normalization of ICP and enjoyed full neurologic recovery after OLT. Laboratory data showed evidence for bilirubin conjugation, decrease in blood ammonia, maintenance of low lactic acid levels, and increase in the ration between the branched chain and aromatic amino acids. No allergic reactions to xenogeneic hepatocytes were observed. The authors conclude that BAL treatment with porcine hepatocytes appears to be safe and can help maintain patients alive and neurologically intact until a liver becomes available for transplantation. (c) 1994 John Wiley & Sons, Inc.     

Hippo信号通路与肝脏稳态调控及疾病发生

肝脏是人体最重要的器官之一,乙肝等病毒性与酒精等非病毒性因素诱发的肝损伤引起肝脏功能衰竭、再生重塑障碍、肝癌等疾病是我国重大社会健康问题,因此,研究肝脏稳态的调控机制对肝病的预防和临床治疗至关重要。Hippo信号通路参与了哺乳动物多种细胞和器官的稳态调控。最近研究表明,Hippo信号通路在肝脏发育、肝细胞命运决定、肝脏再生和癌症发生发展等过程中都发挥了非常重要的作用。因此,Hippo信号通路可成为肝脏相关疾病的治疗提供了新的靶点。本文综述了Hippo信号通路与肝脏稳态调控的相关研究及最新进展,以期为研究肝脏发育和肝脏相关疾病的治疗提供新的思路和策略。     

肝星型细胞分离方法和功能研究进展

肝星型细胞(Hepatic stellate cells,HSCs),又叫储脂细胞(Fat-storing cells,FSCs)或脂肪细胞(lipocytes),是肝脏固有的非实质细胞类型之一,存在于狄氏腔内,以脂滴的形式储存人体维生素A总量的50%–80%。原代HSCs分离方法,目前主要集中于密度梯度离心法结合离心淘洗、HSCs高侧向角的流式分选法、紫外激发的自发荧光或特异性抗体标记的流式细胞术等,将为HSCs生理和病理研究提供坚实的基础。近年来,HSCs的研究蓬勃发展,合作领域不断拓宽。生理状态下,HSCs处于静息状态,合成细胞外基质(Extracellular matrix,ECM)并维持其稳态,同时广泛摄取和储存维生素A,并具有调节肝细胞再生的功能;而病理状态下,HSCs在肝损伤和持续性刺激条件下被激活,增殖活性明显增强,脂滴减少或消失,ECM合成也明显增加,具有收缩性,同时分泌多种促炎因子和粘附分子,并向肌成纤维细胞转变,表明HSCs的活化是肝纤维化发生发展过程中的关键环节之一。有关HSCs的分离和功能研究一直是肝脏细胞学和肝脏病理学研究的热点之一。文中我们将系统总结和探讨HSCs的分离方法和改进策略,及其功能研究进展和具有潜在价值的研究方向。     

不典型原发性肝癌的CT特征分析

目的分析不典型原发性肝癌(PLC)CT动态强化方式。方法回顾性分析临床及病理证实的29例原发性肝癌中4例多期动态增强CT不典型表现。结果 29例病灶平扫均呈低密度,22例肝细胞癌(hepatocellular carcinoma,HCC)增强扫描呈典型改变(动脉期强化,门脉期及平衡期造影剂廓出或门脉期强化,平衡期造影剂廓出)。1例HCC呈渐进性强化呈等密度,再延时扫描出现低密度环;1例肿块出现坏死、囊变并出血,周边持续明显强化并见增粗血管;2例胆管细胞癌(cholangiocarcinoma,CC)呈分叶或不规则,渐进性强化不达等密度,无胆管扩张。结论少部分原发性肝癌因病灶内组织成分不同致影像表现不典型,需结合多相期表现进行分析,必要时应行穿刺取活检,以减少误诊。     

Preclinical characterization of alginate‐poly‐L‐lysine encapsulated HepaRG for extracorporeal liver supply

We recently demonstrated that HepaRG cells encapsulated into 1.5% alginate beads are capable of self‐assembling into spheroids. They adequately differentiate into hepatocyte‐like cells, with hepatic features observed at Day 14 post‐encapsulation required for external bioartificial liver applications. Preliminary investigations performed within a bioreactor under shear stress conditions and using a culture medium mimicking acute liver failure (ALF) highlighted the need to reinforce beads with a polymer coating. We demonstrated in a first step that a poly‐l ‐lysine coating improved the mechanical stability, without altering the metabolic activities necessary for bioartificial liver applications (such as ammonia and lactate elimination). In a second step, we tested the optimized biomass in a newly designed perfused dynamic bioreactor, in the presence of the medium model for pathological plasma for 6 h. Performances of the biomass were enhanced as compared to the steady configuration, demonstrating its efficacy in decreasing the typical toxins of ALF. This type of bioreactor is easy to scale up as it relies on the number of micro‐encapsulated cells, and could provide an adequate hepatic biomass for liver supply. Its design allows it to be integrated into a hybrid artificial/bioartificial liver setup for further clinical studies regarding its impact on ALF animal models.     

Pluripotent plasticity of stem cells and liver repopulation

Different types of stem cells have a role in liver regeneration or fibrous repair during and after several liver diseases. Otherwise, the origin of hepatic and/or extra‐hepatic stem cells in reactive liver repopulation is under controversy. The ability of the human body to self‐repair and replace the cells and tissues of some organs is often evident. It has been estimated that complete renewal of liver tissue takes place in about a year. Replacement of lost liver tissues is accomplished by proliferation of mature hepatocytes, hepatic oval stem cells differentiation, and sinusoidal cells as support. Hepatic oval cells display a distinct phenotype and have been shown to be a bipotential progenitor of two types of epithelial cells found in the liver, hepatocytes, and bile ductular cells. In gastroenterology and hepatology, the first attempts to translate stem cell basic research into novel therapeutic strategies have been made for the treatment of several disorders, such as inflammatory bowel diseases, diabetes mellitus, celiachy, and acute or chronic hepatopaties. In the future, pluripotent plasticity of stem cells will open a variety of clinical application strategies for the treatment of tissue injuries, degenerated organs. The promise of liver stem cells lie in their potential to provide a continuous and readily available source of liver cells that can be used for gene therapy, cell transplant, bio‐artificial liver‐assisted devices, drug toxicology testing, and use as an in vitro model to understand the developmental biology of the liver. Copyright © 2010 John Wiley & Sons, Ltd.     

Percutaneous liver core biopsy in rats: an alternative to minilaparotomy

Sampling of rat hepatic tissue for histomorphological analysis is usually performed in two different ways: either by killing the animals or by minilaparotomy.In this study we describe a percutaneous core biopsy technique which has been used on day 7, 14 and 21 after allogeneic rat liver transplantation (DA → LEW) in order to examine grafts for rejection in different treatment groups. Fifty-two liver biopsies were performed in 24 animals using a 16-gauge intravenous cannula. Forty-five provided usable specimens which were sufficient for both light or electron microscopy and immunohistochemical analyses to determine the degree of graft rejection. In 7 cases (13.5%) sampling was unsuccessful, especially on day 21 after transplantation, as the plastic cannula could not penetrate the hardened tissue. In 3 animals (5.8%) puncture was immediately followed by death due to perforation of the diaphragm or ether intoxication.In conclusion, this technique is a reliable method for providing ample tissue samples from the rat liver with a low risk of complications.