Antioxidants significantly affect the formation of different classes of isoprostanes and neuroprostanes in rat cerebral synaptosomes

Lipid peroxidation has been implicated in the pathogenesis of a number of diseases, including neurodegenerative disorders. Evidence that antioxidants can affect the clinical course of neurodegenerative diseases is limited. In the present study, we examined the ability of five common antioxidants or antioxidant combinations, alpha-tocopherol, gamma-tocopherol, ascorbic acid, GSH ethyl ester, and a combination of ascorbate and alpha-tocopherol, to modulate lipid peroxidation in peroxidizing rat cerebral synaptosomes, a well-characterized model of oxidant injury. In these studies, we quantified isoprostanes (IsoPs) derived from arachidonic acid as an index of whole tissue oxidation and neuroprostanes (NeuroPs) formed from docosahexaenoic acid as a marker of selective neuronal peroxidation. We report that these various antioxidants displayed markedly different capacities to inhibit IsoP and NeuroP formation with the most potent effects on IsoPs observed for ascorbate, GSH ethyl ester, and the alpha-tocopherol-ascorbate combination. alpha-Tocopherol was slightly less potent and gamma-tocopherol significantly less effective. The concentration-response relationships were significantly different for NeuroP formation with the antioxidants being significantly less potent than for IsoP generation. In particular, alpha-tocopherol did not inhibit NeuroP formation at concentrations up to 100 microM. We also determined that tocopherols, in particular alpha-tocopherol, act in vitro as reducing agents to convert IsoP and NeuroP endoperoxides to reduced F-ring compounds, a finding we have observed previously in vivo in brain. These studies are of importance because they have further defined the role of antioxidants to modulate the formation of lipid peroxidation products in peroxidizing brain tissue. In addition, they suggest that alpha-tocopherol may not be a particularly effective agent to inhibit oxidant stress in the terminal compartment of neurons in the central nervous system.     

Novel chemoattractant peptides for human leukocytes

Phospholipase A(2) plays a key role in phagocytic cell functions. By screening a synthetic hexapeptide combinatorial library, we identified 24 novel peptides based on their ability to stimulate arachidonic acid release associated with cytosolic phospholipase A(2) activity in differentiated HL60 cells. The identified peptides, that contain the consensus sequence (K/R/M)KYY(P/V/Y)M, also induce intracellular calcium release in a pertussis toxin-sensitive manner showing specific action on phagocytic leukocytes, but not on other cells. Functionally, the peptides stimulate superoxide generation and chemotactic migration in human neutrophils and monocytes. Four of the tested active peptides were ligands for formyl peptide receptor like 1. Among these, two peptides with the consensus sequence (R/M)KYYYM can induce intracellular calcium release in undifferentiated HL60 cells that do not express formyl peptide receptor like 1, indicating usage of other receptor(s). A study of intracellular signaling in differentiated HL60 cells induced by the peptides has revealed that four of the novel peptides can induce extracellular signal-regulated protein kinase activation via shared and distinct signaling pathways, based on their dependence of phospatidylinositol-3-kinase, protein kinase C, and MEK. These peptides provide previously unavailable tools for study of differential signaling in leukocytes.     

Chronic ethanol consumption impairs receptor-mediated endocytosis of MAA-modified albumin by liver endothelial cells

Alcoholic liver disease has been associated with abnormalities in receptor-mediated endocytosis (RME) which results in abnormal degradation of metabolically altered proteins. Model systems using formaldehyde-modified albumin (f-Alb) have shown an impairment in RME following chronic alcohol consumption utilizing both in situ perfused rat livers and isolated rat liver endothelial cells (LECs). The discovery that alcohol metabolite derived aldehydes can modify proteins prompted a study to determine if malondialdehyde-acetaldehyde-modified albumin (MAA-Alb) would be degraded similar to that reported for f-Alb, and whether ethanol-fed rats would demonstrate an impaired RME with respect to this ligand which occurs as a consequence of chronic ethanol consumption. MAA-Alb was degraded slightly more than f-Alb in both in situ perfused livers and at the single cell level. This degradation was completely inhibited with 100x unlabeled f-Alb, which suggests the use of a similar receptor. Following alcohol consumption there was a 50-60% decrease in MAA-Alb degradation in whole livers and isolated LECs. Utilizing isolated LECs it was determined that impairment in internalization was the most likely mechanism for the decrease in the amount of MAA-Alb that was degraded. These data show that chronic alcohol consumption by rats does in fact impair RME of alcohol metabolite-derived adducted proteins, and this impairment is due to a defect in the post-internalization step rather than the binding or degradation of the modified protein.     

抗坏血酸对细菌脂多糖引起发育毒性保护作用

目的研究抗坏血酸（AA）对细菌脂多糖（LPS）引起宫内胎儿死亡（IUFD）、生长发育迟缓（IUGR）和骨骼发育迟缓的保护作用。方法实验1：LPS组小鼠于妊娠第15～17d经腹腔注射LPS，LPS＋AA组在LPS处理前和／或处理后经腹腔注射给予AA，对照组给予等容量的生理盐水或从。所有孕鼠于妊娠第18d处死。实验2：LPS组小鼠于妊娠第16d注射LPS，LPS＋AA组在LPS处理前和／或处理后经腹腔注射给予AA，对照组给予等容量的生理盐水或AA。LPS处理后6h处死孕鼠。结果LPS＋AA预处理组平均每窝死胎数明显低于单纯LPS处理组，LPS＋从后和预＋后处理组平均每窝死胎数与单纯LPS组比较差异无统计学意义；AA预、后和预＋后处理均显著抑制LPS引起IUGR和枕骨骨化不全。从预和后处理均显著抑制LPS引起母肝、胎肝和胎盘组织脂质过氧化。但从预处理的作用强于后处理。结论从预处理通过抑制LPS引起的氧化应激，预防LPS引起IUFD、IUGR和骨骼发育迟缓；AA后处理和预＋后处理对抗LPS引起IUGR和骨骼发育迟缓，但对LPS引起的IUFD无明显保护作用。     

重组人白细胞介素11对两种血小板减少症患儿骨髓巨核系祖细胞的作用

目的研究重组人白细胞介素11（recombinant human interleukin 11，rhIL-11）对慢性特发性血小板减少性紫癜（chronic idiopathic thrombocytopenic purpura，CITP）与再生障碍性贫血（aplastic anemia，AA）患儿骨髓巨核系祖细胞（megakaryocyte progenitor）体外生长的影响。方法收集17例CITP患儿及14例AA患儿骨髓，对照组为骨髓检查三系造血功能正常、排除血液系统疾病儿童10例。无血清培养各组骨髓单个核细胞（mononuclear cells，MNC），培养体系中包含血小板生成素（TPO）、可溶性补体结合（SCF），IL-3，rhIL-11，或TPO，SCF，IL-3。培养第14天，用流式细胞仪测定CD41^＋细胞率，CD41结合的碱性磷酸酶抗碱性磷酸酶（alkaline phosphatase—anti—alkaline phosphatase，APAAP）桥联酶标技术鉴定半固体培养的巨核细胞集落形成单位（megakaryocyte colony forming unit，CFU—MK）和巨核细胞爆式集落形成单位（megakaryocyte burst forming unit，BFU—MK）。结果rhIL-11联合TPO等细胞因子，可促进对照组、CITP组CFU—MK和BFU—MK生成（P〈0．01），提高CD41^＋细胞率（P〈0．01）；但对AA组，CFU—MK和CD41^＋细胞率无明显的作用（P〉0．05）。结论rhIL-11联合TPO等细胞因子，可促进CITP患儿骨髓巨核系祖细胞在体外无血清培养条件下的增殖，提示rhIL-11具有治疗CITP的潜在价值，但对AA患儿的骨髓巨核系祖细胞生成并无明显的效果。     

Differential development of behavioral tolerance and the subsequent hedonic effects of alcohol in AA and ANA rats

RATIONALE: There at least two ways in which tolerance development to alcohol's behavioral effects could interact with its subsequent intake: 1) tolerance to alcohol's reward or reinforcing effects per se could lead to increased consumption, and 2) tolerance to alcohol's aversive effects could unmask alcohol's rewarding effects. These two mechanisms may differentially interact with preexisting genetic traits underlying alcoholism. OBJECTIVES: Alcohol's subjective attributes were assessed in selectively bred AA and ANA rats after the development of tolerance to alcohol's behaviorally disruptive effects on lever-press performance. METHODS: Rats were trained to press a lever under an FR30 schedule of food presentations. Group-dependent differential access to intoxicated practice, using a typical pre-post drug administration design, was utilized to promote the development of alcohol tolerance in only the group receiving intoxicated practice sessions. Subsequently, rats were trained to associate alcohol with unique place and taste stimuli in order to assess the relative changes in the approach towards, or avoidance of alcohol-related cues in each group. RESULTS: Groups of AA and ANA rats given access to intoxicated practice demonstrated tolerance development. These groups subsequently conditioned place preferences and failed to develop conditioned taste aversions to alcohol. Passive alcohol exposure in the ANA rats set the occasion for the development of a place preference and delayed taste conditioning. AA rats exposed to passive alcohol exposure failed to condition place preferences and developed rapid taste aversions. Saline control rats failed to develop tolerance or place preferences but did condition a robust alcohol-induced taste aversion. CONCLUSIONS: AA and ANA rats differ in their behavioral and pharmacokinetic response to chronic alcohol exposure. Compensatory responses interacting with approach-avoidance behaviors appear to be learned during intoxicated practice in the AA rats and during both intoxicated practice and passive exposure in the ANA rat line.     

大鼠脑梗死面积定量检查的一种方法

脑血管病发病机制及有效的治疗研究均需借助于理想的动物模型,动物模型观测的一个指标是测量不同时期的脑梗死面积;作者采用光化学法诱导的大鼠脑梗死模型,脑梗死灶应用扫描仪按比例扫描入计算机,利用灰度对比,计算梗死面积。1　方法　　雄性SD大鼠20只,由第四军医大学实验动物研究中心提供,体重240±50g,鼠龄12周左右,二级动物。1模型制做方法:大鼠1%戊巴比妥钠(0.3ml/100g)腹腔注射麻醉,尾静脉注射CPD4后10min内,将鼠俯卧位于脑立体定位仪上,沿头颅正中线偏右切开头皮暴露颅骨前沿部位,在前囟门后1.8mm,正中线旁开约2mm,部位为上下肢皮…     

Streptozotocin induced activation of oxidative stress responsive splenic cell signaling pathways: Protective role of arjunolic acid

Present study investigates the beneficial role of arjunolic acid (AA) against the alteration in the cytokine levels and simultaneous activation of oxidative stress responsive signaling pathways in spleen under hyperglycemic condition. Diabetes was induced by injection of streptozotocin (STZ) (at a dose of 70 mg/kg body weight, injected in the tail vain). STZ administration elevated the levels of IL-2 as well as IFN-γ and attenuated the level of TNF-α in the sera of diabetic animals. In addition, hyperglycemia is also associated with the increased production of intracellular reactive intermediates resulting with the elevation in lipid peroxidation, protein carbonylation and reduction in intracellular antioxidant defense. Investigating the oxidative stress responsive cell signaling pathways, increased expressions (immunoreactive concentrations) of phosphorylated p65 as well as its inhibitor protein phospho IκBα and phosphorylated mitogen activated protein kinases (MAPKs) have been observed in diabetic spleen tissue. Studies on isolated splenocytes revealed that hyperglycemia caused disruption of mitochondrial membrane potential, elevation in the concentration of cytosolic cytochrome c as well as activation of caspase 3 leading to apoptotic cell death. Histological examination revealed that diabetic induction depleted the white pulp scoring which is in agreement with the reduced immunological response. Treatment with AA prevented the hyperglycemia and its associated pathogenesis in spleen tissue. Results suggest that AA might act as an anti-diabetic and immunomodulatory agent against hyperglycemia.     

20AA复方氨基酸注射液细菌内毒素检查法的研究

目的研究20AA复方氨基酸注射液对细菌内毒素检查试验的干扰情况，建立其细菌内毒素的限量检查方法。方法参照《中国药典》2005年版二部附录细菌内毒素凝胶限量检查法进行实验，以不同生产厂家、不同批号的鲎试剂对多批供试品进行干扰试验。结果20AA复方氨基酸注射液经4倍稀释后对检测无干扰作用。结论该制剂可用细菌内毒素检查法替代家兔热原检查法控制产品质量，其内毒素限值为含内毒素量应〈1．2EU·ml^-1。