椎基底动脉缺血／再灌注对豚鼠听功能和耳蜗形态学影响

目的 探讨椎基底动脉缺血／再灌注耳蜗损伤后耳蜗病理形态学和听功能改变。方法经颅底径路建立豚鼠椎基底动脉缺血／再灌注耳蜗损伤模型。68只豚鼠随机分成6组：正常组、缺血1h组、缺血再灌注组（按再灌注时间分12h、24h、48h．7d,4组）。各组动物分别于手术前和处死前行听性脑干反应（auditory brainstem response,ABR）测定,观察ABR各波潜伏期、Ⅰ-Ⅲ波间期和Ⅲ波阈值,部分动物观察了缺血时ABR变化。耳蜗组织切片HE染色技术观察组织细胞形态变化。结果血管阻断缺血时ABR表现波形不典型,重复性差,在缺血10～20min后波形逐渐稳定;缺血组与再灌注（12h、24h、48h、7d）各组ABR各波潜伏期和Ⅰ-Ⅲ波间期较正常组延长,Ⅲ波阈值升高,尤以再灌注24h变化最为显著,48h和7d后ABR阈值有所恢复,但不能恢复正常。耳蜗病理形态学改变发现缺血组毛细胞变形肿胀,再灌注（12h、24h、48h．7d）各组损伤进一步加重,再灌注24—48h损伤最重,可见明显外毛细胞缺损,螺旋神经元胞体和神经纤维较正常组减少,血管纹变薄,均以基底转为明显。结论豚鼠椎基底动脉缺血／再灌注时可致耳蜗损伤,表现为听功能和耳蜗组织形态学改变。     

氨氯地平对高胆固醇大鼠心肌缺血再灌注时一氧化氮合酶的影响

目的 :探讨高胆固醇血症大鼠心肌缺血 再灌注损伤时氨氯地平对内皮型一氧化氮合酶 (eNOS)和诱导型一氧化氮合酶 (iNOS)在冠脉血管内皮表达的影响。方法 :雄性Wistar大鼠分 4组 :单纯高胆固醇血症组 ;氨氯地平组 ;氨氯地平 N 甲基亚硝基左旋精氨酸甲酯组 ;氨氯地平 假手术组。大鼠经高胆固醇喂养 6周后 ,开胸结扎左冠状动脉 ,缺血30min后 ,行再灌注 2 0min、2h。分别用免疫组织化学ABC法检测冠脉血管内皮eNOS和iNOS的表达水平。结果 :缺血前 ,氨氯地平可显著降低冠脉血管内皮iNOS表达 (P <0 .0 1)。缺血 30min ,高胆固醇血症组eNOS、iNOS表达明显减少 (P <0 .0 1) ,氨氯地平组eNOS表达上调 (P <0 .0 1) ,iNOS下调 ;再灌注 2 0min时 ,高胆固醇血症组冠脉血管内皮表达iNOS增多 ,氨氯地平组eNOS、iNOS表达明显下调 ;再灌注 2h时 ,氨氯地平组NO水平及eNOS、iNOS表达较高胆固醇血症组轻度降低。各时相点L NAME均可部分阻断氨氯地平对eNOS、iNOS的效应。结论 :在高胆固醇血症时、缺血期及再灌注早期 ,氨氯地平可调节eNOS、iNOS表达 ,减少心肌缺血 再灌注损伤。     

EPO对缺氧缺血性脑损伤新生大鼠脑组织TERT及BCL-2表达的影响

目的:本研究旨在在观察促红细胞生成素(EPO)对缺氧缺血性脑损伤新生大鼠脑组织TERT及Bcl-2表达的影响,探讨EPO对新生大鼠缺氧缺血性脑损伤(HIBD)的保护作用及可能机制.方法:采用单侧颈总动脉结扎后给予低浓度氧制备缺氧缺血性脑损伤动物模型.Wistar新生大鼠90只,随机选取对30只仔鼠作为对照组,剩余60只制作HIBD模型,随机分为HIBD组和EPO组.其中EPO组大鼠在缺氧缺血后立即腹腔内注射EPO5000u/kg,HIBD组给予等容积生理盐水.对造模后即刻、6h、12h、24h、72h各组大鼠每组选6只取脑组织检测TERT及Bcl-2表达情况.结果:对照组可见各时间点脑组织中Bcl-2有极少量的表达;HI BD组在脑组织中TERT于造模后6h开始增加,12h升高明显,24高峰,72h开始下降,各个时间点均高于对照组(P＜0.05).EPO组中TERT蛋白的表达规律与HIBD组相似,在12h和24h时表达量高于HIBD组(P＜0.05).HIBD组大鼠缺氧缺血后6h Bcl-2表达开始增多,12h达高峰,以后逐渐减少,各个时间点均高于对照组(P＜0.05); EPO组Bcl-2表达规律与HIBD组相似,在24h时表达量高于HIBD组(P＜0.05).结论:EPO对新生大鼠缺氧缺血性脑损伤脑组织有保护性作用,此作用可能与其调节TERT及Bcl-2表达水平有关.     

丹参素对新生大鼠缺氧缺血性脑损伤组织iNOS、NOS、NO的影响

目的:观察丹参素对新生大鼠缺氧缺血性脑损伤组织iNOS、NOS、NO的影响并探讨其脑保护作用机制.方法:将78只SD新生大鼠随机分成假手术组(n=6),缺氧缺血模型组(n=18),丹参素低剂量组(n=18),丹参素中剂量组(n=18),丹参素高剂量组(n=18).通过结扎左颈总动脉和吸入8%低氧混合气制备缺氧缺血性脑损伤(HIBD)动物模型.假手术组不进行缺氧缺血处理.丹参素各治疗组按低、中、高剂量分别于造模后0、24 h两个时点按15,30,60 mg·kg-1腹腔注射用生理盐水稀释至0.5 mL的丹参素注射液.缺氧缺血模型组及假手术组于相应时点腹腔注射生理盐水0.5 mL.假手术组于缺氧缺血后6 h,缺氧缺血模型组与各丹参素治疗组于缺氧缺血后6,24,48 h断头取脑,测定脑组织匀浆iNOS、NOS、NO浓度.结果:与假手术组比较,缺氧缺血模型组新生大鼠大脑中iNOS在缺氧缺血后6 h时变化不大;而在缺氧缺血24 h后升高,应用丹参素治疗后回降,呈一定的量效关系,差异有统计学意义(P＜0.05);NOS及NO在缺氧缺血后6,24,48 h均升高,应用丹参素治疗后回降,且呈一定的量效关系,差异有统计学意义(P＜0.05).结论:丹参素能抑制nNOS、iNOS的产生,从而减少过高的NO的产生,而发挥对新生鼠HIBD时脑的保护作用.     

新生鼠脑缺血预处理后海马CA1区脑源性神经营养因子的表达和意义

目的观察脑缺血预处理对新生Wistar大鼠脑缺血再灌注后海马CAl区脑源性神经营养因子(BDNF)表达的影响和意义。方法通过阻断7日龄新生Wistar大鼠右侧颈总动脉45分钟制备脑缺血模型,设置假手术组、缺血再灌注组和预缺血-缺血再灌注组。采用免疫组化方法和计算机图像分析技术检测3组新生鼠不同时点海马CAl区脑组织BDNF的动态变化及3组光镜下脑组织病理改变。结果(1)脑组织病理改变:预缺血组病理损伤较缺血再灌注组轻。(2)BDNF表达: 预缺血-缺血再灌注组BDNF表达在再灌注后3h开始增高,12h达高峰,24h开始下降,与假手术组和缺血再灌注组比较均有显著性差异(P<0．05),3天降至假手术组水平。结论新生鼠脑缺血预处理早期可诱导海马CAl区BDNF表达和合成增加,对防止再次严重的脑缺血损伤有明显的保护作用, 可能与脑缺血后神经细胞的内源性保护机制有关。     

褪黑素对新生鼠缺氧缺血性脑损伤表达NF-κB的影响

目的：探讨褪黑素（melatonin,MT）对新生大鼠缺氧缺血性脑损伤的神经保护作用及作用机制。方法：新生健康7日龄Wistar大鼠120只,随机分为3组：假手术组（40只）、缺氧缺血模型组（40只）、MT治疗组（40只）,参照经典方法建立新生大鼠缺氧缺血性脑损伤（HIBD）模型,MT治疗组于模型制作完成后立刻注射MT10mg/kg1次于腹腔内,脑损伤组则于腹腔内注射等量的0.9%氯化钠注射液。各组分别于手术后6、24、48、72 h取脑组织切片,免疫组织化学方法检测核因子-κB（NF-κB）的表达.结果：与假手术组相比,缺氧缺血组NF-κB表达随时间的变化增加显著（P〈0.01）。与缺氧缺血组相比较,MT治疗组NF-κB表达在12,24,48h三个时间点中下降显著（P〈0.01）。结论：MT对HIBD后海马区神经细胞具有保护作用,其作用机制可能与抑制NF-κB在海马区的持续活化有关。     

神经生长因子对新生大鼠缺氧缺血性脑损伤后脑组织Fas/FasL表达的影响

目的探讨神经生长因子对新生大鼠缺氧缺血性脑损伤后(HIBD)脑组织Fas/FasL表达的影响。方法新生7d Wistar乳鼠120只随机分为3组,每组40只:A组(假手术组),B组(缺血缺氧组),C组[缺血缺氧+神经生长因子(NGF)]干预组。每组根据处死时间不同又分为5个亚组:6h组,12h组,24h组,48h组,72h组,每组各8只。建立HIBD模型,C组在缺血缺氧后即刻给予腹腔注射NGF(50μg·kg-1·d-1)1次/d,连续3d。各组在不同的时间点取脑组织,假手术组也在相应时间点取脑组织,并用免疫组织化学法测定Fas及FasL含量。结果①Fas的表达:A组脑组织在各个时间点均无或有少量表达;B组脑组织在各个时间点均有Fas的表达,且24～48h为表达高峰,以后逐渐下降;C组脑组织在各个时间点均有Fas的表达,但均较B组表达减少。3组各时间点比较差异均有统计学意义(P<0.01)。②FasL的表达:A组脑组织各个时间点均无表达或有弱表达;B组脑组织在各个时间点都有表达,且24～48h为表达高峰,以后逐渐下降;C组脑组织在各个时间点均有FasL的表达,但均较B组表达减少。3组各时间点比较差异均有统计学意义(P<0.01)。结论①新生大鼠HIBD后6,12,24,48,72h脑组织Fas及FasL表达增加,可能与脑缺氧缺血损伤后神经组织的凋亡有关;②NGF治疗后可明显减少新生大鼠HIBD后脑组织Fas及FasL的表达,从而减少脑组织缺氧缺血损伤后凋亡的发生。     

丹参素对新生大鼠缺氧缺血性脑损伤脑组织SOD、MDA的影响

目的 观察丹参素对新生大鼠缺氧缺血性脑损伤脑组织SOD、MDA的影响及探讨丹参素的脑损伤保护作用机理.方法 7日龄SD新生大鼠78只,随机分成5组:假手术组(n =6);缺氧缺血模型组(n =18);丹参素低剂量组(n =18);丹参素中剂量组(n =18);丹参素高剂量组(n =18).通过结扎左颈总动脉和吸入8%低氧混合气制备缺氧缺血性脑损伤(HIBD)动物模型.假手术组不进行缺氧缺血处理.丹参素各治疗组按低、中、高剂量分别于造模后0、24 h两个时点按15 mg/kg、30 mg/kg、60 mg/kg腹腔注射用生理盐水稀释至0.5 ml的丹参素注射液.缺氧缺血模型组及假手术组于相应时点腹腔注射生理盐水0.5 ml.假手术组于缺氧缺血后6 h,HIBD组与各丹参素组于缺氧缺血后6 h、24 h、48 h断头取脑,测定脑组织匀浆SOD、MDA.结果 与假手术组比较,缺氧缺血模型组新生大鼠大脑中MDA水平升高,SOD活性降低;应用丹参素治疗后MDA水平回降,SOD活性回升,且呈剂量效应.差异有统计学意义(P<0.05).结论 丹参素有减轻新生大鼠缺血再灌注时氧自由基引起的氧化损伤作用,从而发挥脑保护作用.     

孕酮干预对缺氧缺血性脑损伤新生鼠脑组织胶质纤维酸性蛋白表达的影响

目的:观察胶质纤维酸性蛋白(GFAP)在缺氧缺血性脑损伤新生鼠脑组织中的表达及孕酮对其影响,从分子水平探讨孕酮对新生鼠缺氧缺血性脑病星形胶质细胞的保护机制。方法:24只新生Wistar大鼠随机均分成3组,假手术组、缺氧缺血组和药物预防组动物,建立缺氧缺血脑病动物模型。假手术组仅分离左侧颈总动脉,不结扎,亦不做缺氧处理。药物预防组动物于建立模型前30min按8mg/kg腹腔注射0.5g/L的孕酮溶液,24h后动物被全部处死,采用免疫组化和RT-PCR方法检测各组大鼠脑组织中GFAP表达的变化。结果:各组大鼠星形胶质细胞中都有GFAP表达,缺氧缺血组的GFAP阳性细胞数和GFAPmRNA的表达水平明显高于假手术组(均P<0.05),药物预防组的GFAP阳性细胞数和GFAPmRNA的表达明显低于缺氧缺血组(均P<0.01)。结论:缺氧缺血性脑损伤可引起新生鼠脑组织GFAP大量表达,孕酮可抑制缺氧缺血后脑组织星形胶质细胞过度表达,发挥抗缺氧缺血性脑损伤的作用。     

α-硫辛酸对顺铂致小鼠耳蜗毛细胞损伤的保护作用的体外研究

目的:研究α-硫辛酸(LA)对顺铂致离体小鼠耳蜗毛细胞损伤的保护作用。方法:分离3～5d的新生昆明种小鼠耳蜗基底膜,在含有1%牛血清白蛋白培养基中培养24h,分为对照组、模型组(顺铂16μg.mL-1)、药物对照(LA0.5mmol.L-1)组和低、高浓度LA(顺铂16μg.mL-1+LA0.2、0.5mmol.L-1)组(n=10),分别加入含相应药物的新鲜培养基2mL,培养24h,观察各组耳蜗毛细胞组织形态变化,计算内、外毛细胞缺失百分率,检测Bax、Bcl-2的表达情况。结果:与对照组比较,模型组小鼠耳蜗毛细胞出现纤毛倒伏、排列紊乱,内、外毛细胞缺失百分率、Bax表达水平明显增加(P<0.01),Bcl-2表达明显减弱(P<0.01);与模型组比较,低、高浓度LA组小鼠耳蜗毛细胞的形态改变明显减轻,内、外毛细胞缺失百分率、Bax表达明显减弱(P<0.05或P<0.01),Bcl-2表达明显增强(P<0.05),且高浓度组改善效果明显优于低浓度组(P<0.05);对照组与药物对照组比较无明显差异(P>0.05)。结论:LA对离体培养的顺铂致小鼠耳蜗毛细胞损伤具有保护作用。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

2-(Acetoxyphenyl)-(Z)-styryl sulfides as cyclooxygenase inhibitors

2-(Acetoxyphenyl)-(Z)-styryl sulfides are described as selective cyclooxygenase-2 (COX-2) inhibitors, useful for treating inflammation and COX-2-mediated disorders including neoplasia. 2-(Acetoxyphenyl)-(Z)-styryl sulfide is claimed to be the most potent COX inhibitor in the series with a COX-2 selectivity ratio of 33. This compound is also claimed to be superior to celecoxib (Celebrex^®, Pfizer) in inhibiting cell growth of colorectal carcinoma cells. In this evaluation, the COX inhibitory activity of this compound is compared to that previously disclosed for diarylheterocycles and 2-(acetoxyphenyl)alkyl sulfides. The validity of the DLD-1 cell line in the growth inhibition studies is questioned based on recent literature reports indicating the lack of COX-2 expression in this cell line.     

Sleep-disordered breathing with chronic opioid use

Chronic opioid use for pain relief or as substitution therapy for illicit drug abuse is prevalent in our societies. In the US, retail distribution of methadone and oxycodone has increased by 824 and 660%, respectively, between 1997 and 2003. μ-Opioids depress respiration and deaths related to illicit and non illicit chronic opioid use are not uncommon. Since 2001 there has been an emerging literature that suggests that chronic opioid use is related to central sleep apnoea of both periodic and non-periodic breathing types, and occurs in ～ 30% of these subjects. The clinical significance of these sleep-related abnormalities are unknown. This review addresses the present knowledge of control of ventilation mechanisms during wakefulness and sleep, the effects of opioids on ventilatory control mechanisms, the sleep-disordered breathing found with chronic opioid use and a discussion regarding the future research directions in this area.     

Drug targets for cognitive enhancement in neuropsychiatric disorders

The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4β2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA_A α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.