Adaptive changes in the nigrostriatal pathway in response to increased 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurodegeneration in the mouse

Although several adaptive mechanisms have been identified that mask the existence of Parkinson's disease and delay the onset and aggravation of motor symptoms, the timescale and implications of this compensatory process remain an enigma. In order to examine: (i) the nature of the dopaminergic adaptive mechanisms that come into action; (ii) their sequential activation in relation to the severity of degeneration; and (iii) their efficacy with regard to the maintenance of a normal level of basal ganglia activity, we analysed the brains of mice treated daily with 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP, 4 mg/kg, i.p.) and killed at 5-day intervals from day 0 (D0) to D20. Our results demonstrate the sequential activation of two compensatory mechanisms: (i) an increase in striatal tyrosine hydroxylase (TH) protein content attested by the persistence of TH immunolabelling up to D15, contrasting with the decrease observed in both the number of nigral TH-immunoreactive neurons (-70.2%) and striatal dopamine content (-38.4%); (ii) a downregulation of DA uptake in surviving terminals at D20 (73.4% of nigral degeneration). At this point, the failure of adaptive mechanisms to maintain striatal dopaminergic homeostasis is also illustrated by an increase in the cytochrome oxidase activity of substantia nigra pars reticulata, a marker of neuronal function. It has been postulated that an increase in dopamine release per pulse could constitute an adaptive mechanism. The data we present from our MPTP mice model infirm this hypothesis. This study explores the link between the degree of nigral degeneration and the sequential activation of dopaminergic compensatory mechanisms in the nigrostriatal pathway and, in so doing, proposes a rethink of the paradigm applied to these mechanisms.     

Efficient synthesis of [11C]befloxatone,a selective radioligand for the in vivo imaging of MAO‐A density using PET

Carbon‐11 labelled befloxatone ((5R)‐5‐(methoxymethyl)‐3‐[4‐[(3R)‐4,4,4‐trifluoro‐3‐hydroxybutoxy]phenyl]‐2‐oxazolidinone) is a reversible and selective monoamine oxidase‐A (MAO‐A) inhibitor and appears to be a new potent PET tracer for the in vivo imaging of MAO‐A density. In this paper, the radiosynthesis of befloxatone was investigated and orientated towards the preparation of multi milliCuries of radiotracer. Typically, using no‐carrier‐added [¹¹C]phosgene, 150–300 mCi (5.55–11.10 GBq) of [¹¹C]befloxatone was obtained within 20 min of radiosynthesis (including HPLC purification) with specific radioactivities ranging from 500 to 2000 mCi/µmol (18.5–74.0 GBq/µmol). The high efficiency of these radiosyntheses allows for multi‐injection protocols and kinetic approaches for absolute quantification of the tracer. Copyright © 2003 John Wiley & Sons, Ltd.     

胃肠术后1号治疗急性弥漫性腹膜炎的研究

目的　探讨胃肠术后 1号治疗急性弥漫性腹膜炎的疗效。方法　测定 2 0例急性弥漫性腹膜炎患者 (随机分为 2组 :对照组 10例 ,治疗组 10例 )血中乳酸、DAO水平。结果　急性弥漫性腹膜炎患者血中乳酸、DAO呈现不同程度升高 ,经治疗随病情好转 ,血中乳酸、DAO呈现不同程度下降 ,而治疗组血中乳酸、DAO下降幅度显著 ,优于对照组 (P <0 .0 5 )。结论　血中乳酸、DAO在急性弥漫性腹膜炎患者病理过程中起重要作用 ,可作为评估急性弥漫性腹膜炎患者严重程度的指标 ,胃肠术后 1号使乳酸、DAO水平下降 ,促进疾病恢复     

T抗原单克隆抗体法在大肠癌筛检中的应用初探

目的 探讨T抗原单克隆抗体法在大肠癌筛检中的临床价值.方法 同时采用T抗原单克隆抗体法和半乳糖氧化酶法检测207例直肠粘液中的T抗原.结果 T抗原单克隆抗体法和半乳糖氧化酶法的敏感性和特异性分别为69.2%、67.3%和64.2%、65.6%,两者的筛检价值无明显差别.结论T抗原单克隆抗体法对大肠癌筛检有较大临床价值,且操作简便.     

Regional differences in brain monoamine oxidase subtypes in an animal model of geriatric depression: effects of olfactory bulbectomy in young versus aged rats

Geriatric depression is often associated dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis, and with poor responsiveness to antidepressants that work through inhibition of monoamine reuptake; accordingly, it has been suggested that MAO inhibitors may represent a therapeutic alternative in this group. In the current study, we evaluated expression of MAO subtypes in brain regions of young and aged rats subjected to olfactory bulbectomy (OBX), a procedure that reproduces many of the biochemical and functional changes associated with human depression. Activities of both MAO A and B were elevated in aged rats as compared to young rats in most regions, but not in the midbrain, and the OBX lesion failed to produce any change in this pattern. These results stand in contrast to the differential effects of glucocorticoids, which reduce brain MAO in young animals but induce activity in aged rats. Our results support the view that the aged brain possesses biochemical characteristics that distinguish its monoamine biochemistry from that of young brain, and that these distinctions may work in conjunction with HPA axis dysregulation to influence the etiology and therapy of geriatric depression. The use of appropriate animal models for depression and for disruption of HPA axis function can allow for the testing of potential human biomarkers (such as platelet MAO) that may serve to predict treatment outcome.     

Modulation of dihydroxyphenylacetaldehyde extracellular levels in vivo in the rat striatum after different kinds of pharmacological treatment

We recently identified the direct product of dopamine (DA) by monoamine-oxidase (MAO) activity, dihydroxyphenylacetaldehyde (DOPALD) in the trans-striatal dialysate. Based on these findings, in this work, we directly measured the variations in DOPALD levels after various kinds of pharmacological treatment in rat striatal extracellular fluid. Using both reversible and irreversible MAO inhibitors, we found that MAO-A inhibition suppressed, whereas MAO-B inhibition did not modify DOPALD levels in the dialysate. The vesicular DA uptake blocker Ro 4-1284 led to an increase in extracellular DA and DOPALD, whereas the increase in extracellular DA obtained after administration of the plasma membrane DA uptake blocker GBR-12909 occurred without concomitant changes in DOPALD extracellular levels. Microinfusions of DA through the dialysis probe or systemic administration of L-DOPA increased striatal DOPALD to a greater extent compared with other DA metabolites, both in intact and in 6-hydroxydopamine (6-OHDA)-lesioned striatum. This study indicates that the direct product of MAO activity within the rat striatum derives from the activity of the isoenzyme MAO-A. The assay of DOPALD, together with DOPAC, represents a reliable tool to measure directly, in freely moving animals, DA oxidative metabolism. As recent studies have shown that microinfusions of exogenous DOPALD might induce cell death, pharmacological modulation of DOPALD levels might also be relevant for an understanding of the mechanisms involved in DA neurotoxicity.     

平肝熄风汤对脑出血大鼠海马细胞色素C氧化酶活性和细胞凋亡影响同步研究

目的 从神经元线粒体能量代谢和细胞凋亡的角度探讨中药复方的平肝熄风汤对脑出血神经元损伤的保护作用机制。方法 采用Ⅶ型胶原酶诱导大鼠脑出血模型，以组织化学方法结合灰度值半定量测定细胞色素C氧化酶(cytochromc c oxidase，CCO)活性，采用Tunel法检测细胞凋亡结果造模12h，脑出血大鼠海马CA1区CCO活性较假手术组明显降低(P＜0.01)，凋亡细胞较假手术组明显增多(P＜0．01)随后均呈进行性加重。用平肝熄风汤治疗后町维持其CCO活性，减少细胞凋亡。结论 脑出血神经元损伤与神经元CCO活性降低及细胞凋亡有关平肝熄风汤能维持线粒体关键酶CCO活性，改善细胞有氧代谢，减少细胞凋亡，此可能为本方对脑出血继发性神经元损伤保护机制之一。     

900MHz微波电磁辐射对原代培养的大鼠脑皮质神经元能量代谢的影响

目的　研究 90 0MHz微波电磁辐射对原代培养的大鼠脑皮质神经元能量代谢的影响。方法　将大鼠脑皮质神经元暴露于 90 0MHz的连续性微波电磁辐射 (SAR =3 2 2mW g、PD =9mW cm2 ) ,每天暴露 2h ,连续 4d或 5d ,及一次性 1 2h暴露 ,以细胞色素氧化酶为观察指标 ,研究微波对神经元能量代谢的影响。结果　微波电磁辐射可使神经元细胞色素氧化酶活性降低。结论　神经元细胞色素氧化酶活性的改变并非“致热效应”所致 ;微波电磁辐射对神经元细胞色素氧化酶活性影响有蓄积毒性作用 ,其影响在一定程度上是可恢复的 ,并且与神经元接受微波辐射时细胞培养年龄关系不密切。     

银杏叶提取物对兔缺血再灌注损伤后视网膜线粒体功能的保护作用

目的　观察新西兰兔缺血再灌注时视网膜细胞线粒体功能的改变及银杏叶提取物对此改变的影响。方法　 30只 (6 0眼 )动物随机分为假手术组 10只 (2 0眼 )、模型对照组10只 (2 0眼 )和银杏叶提取物治疗组 10只 (2 0眼 )。造模后取视网膜组织 ,分离视网膜细胞线粒体。用氧电极法测定线粒体的呼吸功能及还原性辅酶Ⅰ (NADH)氧化酶、琥珀酸氧化酶和细胞色素氧化酶的活性。结果　新西兰兔缺血后视网膜细胞线粒体的呼吸功能有所损伤 ,表现为呼吸控制率、磷氧比和氧化磷酸化效率均较假手术组有不同程度的降低 ,各种氧化酶的活性亦有明显下降。银杏叶提取物组动物的这种改变明显减轻。结论新西兰兔视网膜缺血再灌注后视网膜细胞线粒体的功能明显受损 ,而银杏叶提取物对此损伤具有一定的保护作用。     

乙醇氧化酶两点速率法测定血清微量乙醇

目的：建立一个灵敏、准确、特异、试剂稳定的乙醇氧化酶法用于测定血清微量乙醇浓度。方法：利用乙醇氧化酶与过氧化物酶偶联，通过优化反应体系及自动生化分析仪分析参数，采用两点速率法对乙醇进行分析。结果：乙醇浓度在2000mg／L以下线性良好；批内RSD小于2．81％，批间RSD小于4．51％；平均回收率为100．7％；本法（Y）与气相色谱法（X）比较具有良好的相关性，Y=0．996X＋3．58，r=0．981。胆红素159．1μmol／L、甘油三酯14．31mmol／L、血红蛋白5．8g／L以下对本法测定乙醇结果无干扰。结论：建立的两点速率法测定乙醇灵敏度高、准确度、特异性均较好，特别适合于血清乙醇浓度处于轻度超标的疑似酒后者的标本检测。