紫苏叶提取物及其保健功效的研究

机体的衰老和老年性疾病的形成是一个缓慢的发展过程,它涉及自由基对机体连续性损伤及修复的交替反应。衰老的自由基学说认为,衰老是机体组织中持续进行的活性自由基反应引起的有害作用积累的结果。活性氧自由基可以引发生物膜的不饱和脂肪酸发生脂质氧化反应,损伤膜结构和功能,导致功能和代谢紊乱。脂质过氧化产物丙二醛易使生物大分子产生交联作用,除形成常见的“寿斑”外,还可导致酶的失活或ＤＮＡ的变质,乃至诱发细胞的癌变。Ｈ２Ｏ２是活性自由基反应的前提,参与自由基反应,是引发人体不饱和脂肪酸发生脂质过氧化的重要物质。…     

蜂胶抗氧化作用的研究进展

蜂胶对机体的诸多保护功效与蜂胶的抗氧化性有着密切的关系。机体的氧化反应中部分氧产生过氧化氢、超氧化阴离子和自由基羟基等活性氧及自由基。随着年龄的增长，氧化反应的产物活性氧和自由基便逐渐积蓄在机体的组织内，引起人体的老化。活性氧与不饱和脂肪酸反应生成过氧化脂质，而过氧化脂质是引发动脉粥样硬化和白内障的物质之一。紫外线引起的皮肤老化、药物中毒、放射线损伤、癌症、糖尿病、心血管疾病以及老年病等也都与活性氧和自由基有关。     

鸡蛋中的脂类过氧化反应与保护

鸡蛋是人的重要食物,但其在贮藏、烹制和加工过程中发生的过氧化作用对鸡蛋的稳定性和质量影响较大。脂类的过氧化作用是自由基对不饱和脂肪酸的作用,过氧化反应发生的过程,也是一个导致脂肪酸酸败和腐败的过程。贮藏的时间、温度、光照和制作过程中的ｐＨ值等均能影响鸡蛋中脂质过氧化物。合成抗氧化剂已广泛应用于食品行业,但为安全起见,人们正在积极研究天然抗氧化剂,特别是从植物中提取的天然抗氧化剂。１　鸡蛋中的脂类过氧化反应及其机理人们早就在鸡蛋及其制品中发现了脂质过氧化物（ＬＰＯ）（Ｔｓａｉ,１９８５;Ｐｉｋｅ,…     

山羊内毒素血症心肌线粒体自由基损伤及氨基胍对其的影响

自由基的严重毒害之一是它与游离或结合状态的不饱和脂肪酸作用,使之发生过氧化反应(脂质过氧化),从而导致生物膜的破坏.脂质过氧化可产生一系列的代谢产物,其中包括希夫氏碱,共轭二烯和丙二醛(MDA).线粒体膜蛋白是脂质过氧化作用的主要损伤靶位,位于膜上的酶其活性受抑制,进一步地加剧了线粒体的损伤.     

茶多酚（GTPP）的抗脂质过氧化作用

活性氧和自由基引发的脂质过氧化反应与细胞突变或机体衰老及多种疾病的发生发展密切相关［１］。细胞代谢过程中连续不断产生的具有高度活性的自由基和细胞自身的抗氧化酶不断消除作用的失衡,致使体内自由基过剩,自由基及其诱导的氧化反应会引起细胞膜中含量丰富的脂类物质发生氧化作用,产生过氧化脂质（ＬＰＯ）。ＬＰＯ的产生和积累,导致生物膜功能障碍和膜酶及其他生物大分子的损伤,从而影响细胞活性物质的正常代谢,促进衰老和诱发疾病。这种过量自由基导致脂质过氧化反应的非组织特异性,使得体内重要脏器如肝、心、脑等都有受害…     

不同运动训练强度对小鼠血清MDA含量和SOD活性的影响

正机体通过酶系统与非酶系统产生氧自由基,自由基能攻击生物膜中的多不饱和脂肪酸,引发脂质过氧化作用,并因此形成脂质过氧化物,其中丙二醛(MDA)就是生物体内自由基作用于脂质发生过氧化反应的终产物,是膜脂过氧化最重要的产物之一。它的产生能加剧膜的损伤,引起蛋白质、核酸等生命大分子的交联聚合,导致细胞代谢及功能障碍,甚至死亡,具有细胞毒性。因此,MDA含量常被作为了解膜     

大黄致家兔脾气虚证动物模型血浆MDA含量变化的研究

为了解脾(气)虚证与自由基反应的关系,我们对16只大白兔(其中健康对照组8只,脾气虚模型复制组8只)于制造脾气虚模型前后两次采血,进行血浆丙二醛(malondialdehyde,MDA)含量测定。结果表明,脾气虚证组中血浆MDA含量显著高于实验前两组健康家兔,脾气虚证与自由基反应有关,脂质过氧化损伤是脾气虚证的病理基础之一。     

活性氧与营养素

活性氧是指含有氧元素且较Ｏ2活泼的自由基或非自由基的统称。在1931年Ｈａｂｅｒ就曾假设有·Ｏ-2(超氧根阴离子)存在,需氧生物2%～5%的摄入氧在氧化反应中可接受单电子或被歧化或被其他物质作用生成活性氧。饲料的加工、贮藏条件或其他因素不适宜,也易引起脂质过氧化产生活性氧。动物营养不良或发生病变,可导致活性氧的积累。现经试验证实,除·Ｏ2-外,常见的活性氧还有·ＯＨ(羟自由基)、ＨＯ2·-(超氧化物自由基)、Ｈ2Ｏ2(双氧水)、1Ｏ2(单线态氧)以及由自由基引起的脂质过氧化链式反应的中间产物ＲＯ·、ＲＯＯ·、ＲＯＯＨ等,其中起始…     

维生素E对肉羊体内抗氧化功能影响的研究

生命过程中的许多化学反应部有自由基的参与，所以自由基地是与生命同步和共存的，但是动物机体若因细胞活动和各种应激所产生的自由基过量，这些自由基一旦在体内大量积累，则诱发脂质过氧化（LPO）反应。     

鸡蛋中的脂类过氧化反应与保护

鸡蛋是人的重要食物,但其在贮藏、烹制和加工过程中发生的过氧化作用对鸡蛋的稳定性和质量影响较大。脂类的过氧化作用是自由基对不饱和脂肪酸的作用,过氧化反应发生的过程,也是一个导致脂肪酸酸败和腐败的过程。贮藏的时间、温度、光照和制做过程中的ｐＨ值等均能影响鸡蛋中脂质过氧化物。合成抗氧化剂已广泛应用于食品行业,但为安全起见,人们正在积极研究天然抗氧化剂,特别是从植物中提取的天然抗氧化剂。１鸡蛋中的脂类过氧化反应及其机理人们早就在鸡蛋及其制品中发现了脂质过氧化物（ＬＰＯ）（Ｔｓａｉ,１９８５;Ｐｉｋｅ,１９８５…     

硫酸亚铁防氧化技术的试验

作为饲料添加剂而广泛使用的硫酸亚铁,在储存过程中亚铁易氧化成高价铁。试验研究了防止硫酸亚铁氧化的方法,并对造成其氧化的原因进行了分析。     

Expressions of protein oxidation markers, dityrosine and advanced oxidation protein products in Cisplatin-induced nephrotoxicity in rats

The purpose of this study was to evaluate whether dityrosine and advanced oxidation protein products (AOPP) reflect the severity of cisplatin-induced nephrotoxicity. Immunoexpression of dityrosine in kidneys and plasma AOPP concentration were examined up to day 4 post-cisplatin injection in rats. Cisplatin injection induced tubular injury on days 2-4 after injection and increased serum creatinine and BUN on days 3 and 4. On days 2-4, dityrosine was immunostained in the cytoplasm of damaged tubular cells, and their immunostaining intensity increased time-dependently. Plasma AOPP levels were significantly increased on days 3 and 4. These results suggest that expressions of dityrosine and AOPP were associated with the severity of renal injury and may be useful markers for the development of cisplatin-induced nephrotoxicity.     

Expressions of protein oxidation markers, dityrosine and advanced oxidation protein products in acetaminophen-induced liver injury in rats

The purpose of this study was to evaluate whether dityrosine and advanced oxidation protein products (AOPP) were useful as biomarkers for monitoring the development of acetaminophen-induced liver injury. Dityrosine immunoexpression in the liver along with plasma AOPP concentration was examined up to 24 hr post-acetaminophen injection in rats. The histopathological changes in the liver appeared 3 hr after acetaminophen injection and became exacerbated with time. The immunohistological expression of dityrosine was also first detected in the damaged hepatocytes 3 hr after the injection and became more accentuated at 6, 12 and 24 hr in accompanying with the elevation of plasma AOPP concentration. These results suggested that dityrosine and AOPP expressions might be useful biomarkers for monitoring the development of acetaminophen-induced liver injury.     

Nutrient oxidation and lipogenesis in hens

Introduction Indirect calorimetry based on measurements of gas exchange has been used successfully during the last century in order to estimate energetic values of feedstuffs and animals’ requirement for nutrients and energy. Recently, measurements of gas exchange have been used to calculate nutrient oxidation and lipogenesis in the intact body of man (T horbek et al. 1994), pigs (C hwalibog et al. 1992; C hwalibog and T horbek 1995), calves (C hwalibog et al. 1996; C hwalibog et al. 1997a), mink (T auson et al. 1997) and rats (C hwalibog et al. 1998). In the present paper a similar approach has been used to quantify nutrient metabolism in laying hens in accordance with a calculation method first proposed by C hwalibog et al. (1992) and later modified as outlined in Fig. 1. According to this biological model digested protein (DP) which is equal to PROT _{– group} is utilized for retention in eggs (OP), ovary and body (OBP), whereas deaminated amino acids are oxidized (OXP) with concomitant excretion of energy with nitrogenous substances in urine (UE_N) and contribution of energy (GLUC) to carbohydrate metabolism. Digested carbohydrate (DCHO) together with GLUC constitute the CHO _{– group}, which is retained in eggs (OCHO), oxidized (OXCHO) and used for lipogenesis (LIPO). Digested fat (DFAT) and lipids from lipogenesis constitute the FAT _{– group}, which is incorporated into eggs (OF), ovary + body (OBF) and oxidized (OXF). Both CHO and FAT metabolism contribute with energy containing products excreted with urine (UE_N-free). The energy from OXP, OXCHO and OXF make up the total heat production (HE). The validity of the method will be discussed later. The aim of this study was to demonstrate how data from gas exchange measurements in combination with nitrogen and energy balances can be applied in order to calculate nutrient oxidation and the quantities of substrates used for retention and lipogenesis processes, and furthermore, to elucidate differences in nutrient oxidation and lipogenesis in relation to different housing conditions and genotypes of laying hens.     

Production and oxidation of wool grease after shearing

OBJECTIVE: To measure the production and amount of oxidation of wool grease secreted immediately after shearing. To identify components of wool grease that might act as a carrier to facilitate lateral diffusion of topically applied insecticides. DESIGN: Fine-wool Merino sheep were shorn and residual greasy wool was collected from the sheep's flank. The quantity of grease produced, and the amount of oxidation was measured during 18 days after shearing. Wool grease was fractionated into five component groups based on their polarity and the degree of oxidation in these fractions determined. RESULTS: There was a 24% increase in grease production within 2 days after shearing but secretions returned to pre-shearing amounts after 4 days. During this period wool grease oxidized rapidly. Of the grease fractions examined, sterol and wax esters remained essentially unoxidized whereas free sterols such as cholesterol and lanosterol, fatty acids and polar lipids, aldehydes and alcohols were extensively oxidized within 7 days after shearing. CONCLUSION: The transient increase in grease production after shearing may facilitate diffusion of topically applied synthetic pyrethroid insecticides. Oxidation of grease components may then contain the insecticide and limit further diffusion. Incorporating the insecticide in non-oxidising fractions of wool grease may make insecticide dispersion more efficient.     

鱼粉氧化对水产动物健康的影响

鱼粉是饲料的重要原料，尤其是水产动物配合饲料中不可缺少的动物性蛋白源(鱼粉在水产配合饲料中的比例30％～50％，甚至更高)，其蛋白含量高、品质好、氨基酸组成适于与其他饲料原料配伍，赖氨酸和蛋氨酸含量高，而精氨酸含量低，与大多数饲料原料的氨基酸组成相反。含丰富的矿物质及维生素。     

Influence of early postmortem protein oxidation on beef quality

The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4 degrees C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) alpha-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.     

Substrate oxidation and retention in pigs and poultry

A model combining data from gas exchange measurements with nutrient balances, demonstrating energy transfer between the pools of protein, carbohydrate and fat and their partition in the body, is described. Data from energy metabolism experiments with growing pigs and laying hens is incorporated into the model in order to illustrate methods of calculations and interpretations of the model. The experiments with pigs were carried out with growing pigs (20–100 kg) measured alternately on high (ad libitum) and low (near maintenance) feed levels on diets with low or high fat concentration. When energy intake from digested carbohydrate covered the requirements for growth, heat from oxidation of carbohydrate contributed 85–90% to the total heat production, while there was no net oxidation of fat. When the intake of digested carbohydrate was not sufficient to cover requirements, fat was mobilized from the body and oxidized. Energy from oxidation of carbohydrate was in all measurements below the energy in the carbohydrate pool, indicating transfer of energy from carbohydrate to fat metabolism in the process of de novo lipogeneis. The experiments with hens were carried out with 62 hens during the laying period from 26 to 47 weeks of age. The hens originated from two strains (A and B); they were kept in battery cages either individually or 3 hens/cage and fed ad libitum with an identical commercial diet. The partition of the protein pool between oxidation and retention was not influenced by the housing system. However, the genetic origin of hens effected protein utilization with relatively lower oxidation and higher retention in Strain B. The main part of the carbohydrate pool was oxidized (45–60%), but the hens kept individually oxidized more carbohydrate than those kept 3 hens/cage. Further, there were significant differences between the strains. Generally, about half of the fat pool originated from de novo lipogenesis from carbohydrate, indicating the importance of this process for fat retention in eggs. Fat oxidation depended on the energy supply from carbohydrate, hence with higher use of carbohydrate for oxidation in Strain B less fat was oxidized and more was used for fat synthesis. The presented results indicate that by combining results from gas exchange measurements with nitrogen and energy balances it is possible to evaluate the contribution of nutrients to the oxidative processes and the energy transfer between substrate pools.     

The effect of outside conditions on anaerobic ammonia oxidation reaction

Organic carbon,inorganic carbon,temperature,p H and ORP are all to have a certain influence on the anaerobic ammonia oxidation reaction.We can draw some conclusions on the optimum conditions of anaerobic ammonia oxidation reaction.The optimum temperature of the anaerobic ammonia oxidation reaction is 30-35℃.And the optimum p H of the anaerobic ammonia reaction is 7.5-8.3.The presence of organic matters can affect the anaerobic ammonia reaction,and different organic matters have different influence on it.The concentration of the inorganic carbon also exist great influence on the reaction.High inorganic carbon concentration also can inhibit anaerobic ammonia oxidation reaction.