重金属铅对农产品的污染与安全标准

阐述重金属铅污染的来源其对农产品污染所带来的严重后果,以及如何防治重金属铅对农产品的污染给出相关建议,并探讨重金属铅的安全标准.     

提高石墨炉原子吸收法测量重金属元素铅的准确度分析

现阶段重金属元素铅测量方法有多种,本文章选用的方法是最为经典的常规方法：常压消解后石墨炉原子吸收法测定铅的含量。通过对比试验,分析常压消解后石墨炉原子吸收法测定铅过程中各个影响因素对其准确度的影响程度。     

蔬菜重金属污染现状及研究进展

随着工业化快速发展,蔬菜重金属污染也随之加剧.阐述蔬菜重金属污染、我国蔬菜重金属污染现状、蔬菜对重金属吸收的富集规律,提出蔬菜重金属污染的防治对策,为下一步开展蔬菜重金属污染研究提供参考依据.     

重金属国内外研究进展

燃煤电站是重金属污染的主要排放源之一,燃烧过程中重金属元素有些以气相形式排入大气。砷、铅、镉、铬属于煤燃烧过程中易挥发的元素,国内外对燃煤中重金属控制的相关工作正处于起步阶段,相关研究比较少,我国缺少燃煤电站砷、铅、镉、铬排放的真实数据、以及各位置重金属元素的分布情况。     

微生物处理重金属技术的研究进展

本文对微生物吸附法处理重金属污水的研究和应用现状进行了综合评述。介绍了常用的微生物吸附剂,比较了不同种类微生物吸附剂的差别。讨论了微生物吸附剂处理效果的影响因素和吸附机理。最后,综述了国内外有关重金属污水微生物吸附法处理技术的研究成果,提出了未来的研究方向及发展趋势。     

水体沉积物重金属的赋存形态及其质量评价方法的研究进展

沉积物环境质量的评价是当前水环境污染研究的热点问题之一,其研究的焦点集中于沉积物中污染物的生物可利用性和生物毒性,而化学形态决定了重金属在沉积物中的这些性质。就上述内容进行了综述和探讨,并介绍了当前水体沉积物质量基准的建立状况。     

五水硫酸铜母液中微量重金属铅去除方法的探索

对利用含铜废液生产五水硫酸铜产生的母液进行除铅实验,在恒温的条件下,通过调节pH值在1．5的条件下加入适量的氯化钡,反应后的静置时间为4小时,能使五水硫酸铜母液中铅的去除率达到99．8％以上。     

水环境重金属污染对水生动物的生态效应

本文通过水环境中重金属在水生动物体内的积蓄、毒害及中毒荆量等方面的分析,阐述了重金属污染水体对水生动物生长发育等生命活动的危害和影响,同时提出了减轻重金属污染的若干方法和途径.     

土壤重金属含量与粮食生产安全性的研究进展

土壤是人类赖以生存的主要自然资源之一。随着工业生产规模不断扩大、城镇化的快速发展,许多有害重金属进入土壤系统,造成农田生态破坏和环境质量恶化。直接导致粮食作物如水稻、玉米、小麦的生长受阻,粮食中重金属含量增加,从而降低粮食的产量和品质,严重影响粮食的生产安全。文章分析了通过改善农艺措施、使用土壤改良剂、植物修复等措施来保护土壤资源,提高土壤质量,并通过筛选重金属富集能力低的粮食作物品种来降低粮食中重金属的含量,提高粮食生产的安全性。     

皂素淋洗法去除土壤中重金属的研究进展

皂素作为一种淋洗剂可以很好地应用于重金属污染土壤的治理修复中。文中论述了皂素的结构特性和淋洗去除土壤重金属的原理,重点阐述了皂素淋洗法去除土壤中重金属的影响因素,并对未来的研究工作做了展望。     

Stress,Oxidative Injury and Disease

The living system on earth is largely using oxygen for burning metabolic fuel for energy. The toxicity of oxygen is largely due to the formation of free radicals in living systems. Stress is also responsible for the generation of free radicals. The evidence for the involvement of free radicals and oxidative injury in producing metabolic disturbance, maladjustment and many diseases has been accumulating since long. It is largely believed that the root cause of many chronic diseases is stress induced free radicals and resultant oxidative injury.     

Study of Oxidative Stress in Vitiligo

Vitiligo is an idiopathic, acquired, circumscribed, hypomelanotic skin disorder, characterized by milky white patches of different sizes and shapes. It is due to the destruction of melanocytes resulting in the absence of pigment production of the skin and mucosal surfaces. Oxidative stress has been implicated in pathophysiology of vitiligo. To study the activity of blood Superoxide dismutase (SOD) and Glutathione peroxidase (GPx) in vitiligo patients. A case–control study was conducted in which 100 patients were enrolled after written consent. 50 cases were of active vitiligo and 50 served as control (25 healthy control and 25 with stable vitiligo). SOD—In our study, among the active vitiligo cases 90% had high level of SOD and 10% had normal level of SOD. Among the stable vitiligo controls, 92% had normal level of SOD and 8% had low levels of SOD.The difference between active vitiligo cases and stable vitiligo control as well as with healthy control was statistically significant (P value < 0.05). GPx—Among the active vitiligo cases 74% had normal GPx levels, 22% had low and only 4% had high levels of GPx. Among the stable vitiligo controls, 64% had normal GPx levels, 16% had low, and 20% had high levels of GPx. The difference between active vitiligo cases and stable vitiligo control as well as with healthy control was statistically not significant (P value > 0.05). Our study shows that oxidative stress is involved in the pathophysiology of vitiligo, as indicated by the high levels of serum superoxide dismutase activity.     

Effect of Oxidized Phosphatidylcholine on Biomarkers of Oxidative Stress in Rats

In this study it was planned to investigate the effect of oxidized phosphatidylcholine (derived from egg) feeding on lipid peroxidation of different tissues in rats. Male Wistar albino rats were fed oxidized and unoxidized phosphatidylcholine for 2 and 4 weeks, respectively. During the period of study food intake and body weights of animals increased gradually. Animals fed oxidized phosphatidylcholine for 2 and 4 weeks showed 33 and 15% spontaneous hemolysis of red blood cells in vitro. Under identical experimental conditions animals given unoxidized phosphatidylcholine showed 14.5 and 13.4% hemolysis for 2 and 4 week’s period, respectively. Thiobarbituric acid reactive substances (TBARS) level in thymus, spleen, kidney, heart, liver and lung significantly increased in rats given oxidized phosphatidylcholine as compared to unoxidized group. Furthermore, in oxidized phosphatidylcholine group TBARS values in kidney, liver and lungs continued to rise for 4 weeks of treatment while TBARS level in heart, spleen and thymus was found to be decreased at the end of 4 weeks of oxidized phosphatidylcholine feeding. Plasma triacylglycerol and cholesterol was found to increase in rats who had received oxidized phosphatidylcholine for 2 weeks. These findings suggest that excess and persistent intake of oxidized phosphatidylcholine can cause significant damage to organs.     

Oxidative Stress and Skin Cancer: An Overview

Skin is the largest body organ that serves as an important environmental interface providing a protective envelope that is crucial for homeostasis. On the other hand, it is a major target for toxic insult by a broad spectrum of physical and chemical agents that are capable of altering its structure and function. There are a large number of dietary contaminants and drugs can manifest their toxicity in skin. These environmental toxicants or their metabolites are inherent oxidants and/or directly or indirectly drive the production of a variety of reactive oxidants also known as reactive oxygen species. These are short-lived entities that are continuously generated at low levels during the course of normal aerobic metabolism. These are believed to activate proliferative and cell survival signaling that can alter apoptotic pathways that may be involved in the pathogenesis of a number of skin disorders. The skin possesses an array of antioxidant defense mechanisms that interact with toxicants to obviate their deleterious effect. The “antioxidant power” of a food is an expression of its capability both to defend the human organism from the action of the free radicals and to prevent degenerative disorders. Plants like olive trees have their own built-in protection against the oxidative damage of the sun, and these built-in protectors function as cell protectors in our own body. Although many antioxidants have shown substantive efficacy in cell culture systems and in animal models of oxidant injury, unequivocal confirmation of their beneficial effects in human populations has proven elusive.     

Role of Oxidative Stress in Various Stages of Psoriasis

Psoriasis is a chronic inflammatory, proliferative skin disease characterized by pathological skin lesions due to various exogenous and endogenous factors. It is associated with a number of biochemical and immunological disturbances. Recently, it has been suggested that increased reactive oxygen species (ROS) production and compromised function of antioxidant system may be involved in the pathogenesis of this disease. In the present study, 90 psoriasis patients were selected. Disease severity was assessed by psoriasis area severity index score and grouped as mild, moderate and severe (each group consists of 30 subjects) and compared with 30 healthy controls. Serum levels of malondialdehyde, nitric oxide end products and the activities of antioxidant enzymes such as erythrocyte-superoxide dismutase, catalase and total antioxidant status were investigated in these groups/subjects. As compared to controls, we found severitywise significantly increased serum malondialdehyde, nitric oxide end products with decrease in erythrocyte-superoxide dismutase activity, catalase activity and total antioxidant status in patients with psoriasis suggesting worsening of the disease. It seems to be linked with the enhancement of Reactive Oxygen Species production and decreased antioxidant potential in psoriasis.     

Thiamine Deficiency Induced Dietary Disparity Promotes Oxidative Stress and Neurodegeneration

Thiamine or vitamin B1 is a well known coenzyme and nutrient necessary for the assembly and right functioning of several enzymes involved in the energy metabolism. The present study evaluates oxidative stress and prevalence of neurodegenerative conditions in the brain following TD. The study was carried out on mice (Musmusculus) in three groups, namely control and thiamine-deficient group for 8 (TD 8) and 10 (TD 10) days. Lipid peroxidation was determined in terms of reduced glutathione (GSH) and thiobarbituric acid reactive substance (TBARS). The level of antioxidant enzymes such as catalase (CAT), glutathione reductase, glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione transferase (GST) were measured along with histopathological studies in all the groups. There was significant increase in the TBARS levels in group II (TD 8) and group III (TD 10) animals in comparison to controls (Group I). The GSH levels were found to be lower in both the treated groups. The level of antioxidant enzymes CAT (p < 0.001), glutathione reductase (p < 0.001), GPx (p < 0.001), SOD (p < 0.0001) were found to be significantly reduced in group III (TD 10) in comparison to controls. Histopathological studies showed moderated to extensive neuronal loss in group II and group III in comparison to control group. The increase in LPO and reduction in enzymes CAT, glutathione reductase, GPx, SOD, and GST following TD suggests mitochondrial dysfunction, neuronal loss acute oxidative stress that may impair the functioning of the brain along with the rise of neurodegenerative conditions in the affected animals.     

合成生物学工业应用的现状和展望

通过合成生物学技术可以实现化学品的生物合成,从而为摆脱石油资源依赖提供了可能。合成生物学技术的发展极大地提高了微生物细胞工厂生产化学品的能力,创造的新菌种、新工艺可以有效替代传统工艺,显著降低污染,大幅减少能耗,提升传统发酵行业的技术水平。文章对利用合成生物学技术构建细胞工厂以及构建多酶分子机器来生产化学品的关键因素和典型案例进行了综述,并对合成生物学技术工业应用的未来进行了展望。     

Idiopathic Fetal Growth Restriction: Repercussion of Modulation in Oxidative Stress

Oxidative stress has been proposed as one of the causes involved in idiopathic fetal growth restriction (IFGR). However, the exact relationship between oxidative stress and IFGR is not understood. This study aimed at understanding the role of oxidative stress and antioxidant status in IFGR materno-fetal dyads and matched controls. 75 materno-fetal dyads with IFGR were enrolled with equal number of normal low risk controls. Malondialdehyde (MDA) levels were measured as marker of oxidative stress, while paraoxonase-1 (PON1) activity and total antioxidant capacity (TAC) of serum were measured as markers of antioxidant status. MDA levels were increased in both maternal and cord blood of IFGR neonates as compared to controls (p < 0.001). TAC of serum were found to be decreased in IFGR (both maternal and cord blood) as compared to controls (p < 0.001; p < 0.05, respectively). PON1 activity was found to be decreased in the IFGR mothers while it was found increased in IFGR cord blood (p < 0.01; p < 0.001)). IFGR is a state of increased oxidative stress. Decreased PON1 enzymatic activity in mothers is also associated with IFGR.     

Evaluation of Oxidative Stress and Antioxidant Status in Pregnant Anemic Women

The present study was conducted to investigate the oxidant–antioxidant status in iron deficient pregnant anemic women. One hundred thirty pregnant women with iron deficiency anemia (IDA) were divided into three groups, namely mild (50), moderate (50) and severe (30) anemic along with pregnant healthy women as controls (50). The complete blood count, plasma lipid peroxidation products, enzymatic and non-enzymatic antioxidants were measured according to respective protocols. The levels of complete blood count, iron, ferritin along with antioxidant enzymes namely catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and reduced glutathione were significantly reduced in all IDA groups. However, the level of oxidized glutathione, lipid peroxides, protein carbonyls, conjugated dienes were found significantly increased in all anemic patients. Antioxidant vitamins, namely C, E and A were also found significantly decreased in IDA patients. On the basis of our results, it may be concluded that IDA tends to increase the pro-oxidant components, which may result in various complications including peroxidation of vital body molecules resulting in increased risk for pregnant women as well as fetus.