福建产舟山眼镜蛇毒细胞毒素的快速分离纯化及鉴定

目的 从舟山眼镜蛇毒中分离纯化细胞毒素(CTX)，并鉴定其理化性质。方法 采用SP—Sephadex C-25阳离子交换色谱及Sephasil Peptide C18反相高效液相色谱法从舟山眼镜蛇毒中分离纯化CTX，SDS—PAGE(Tris—Tricine系统)鉴定纯度，Edman降解法测定N端氨基酸序列。结果 粗毒经阳离子交换色谱，得到14个蛋白峰，其中第X～XⅢ峰具CTX活性；再分别经反相色谱纯化，得到4个CTX．总得率为32.48％；SDS—PAGE显示为均一蛋白，分子量依次为：7．28，7．33，7．24和7．38kD；测定它们N端20个氨基酸序列。结论 采用阳离子交换和反相高效液相色谱可快速、高效地从眼镜蛇毒中获得4个CTX纯品。     

A型肉毒毒素多表位串联体的设计、表达、纯化及鉴定

目的:设计、表达两个A型肉毒毒素多表位串联体.方法:从文献报道的A型肉毒毒素(botulinum neurotoxin type A,BoNT/A)的表位及生物信息学方法预测得到的B细胞表位中遴选表位,并加入适当的辅助性元件,设计多表位串联体A、B.对其基因进行优化后,经重叠PCR方法合成串联体A、B的全长基因.分别插入原核表达载体pQE-30,再转化E.coli M15[pREP4]感受态细胞中进行诱导表达,以金属螯合亲和层析法纯化重组蛋白,并进行鉴定.结果与结论:成功设计并构建了两个多表位串联体A、B,并在E.coli中以包涵体形式获得高效表达.Ni-NTA法纯化后分别获得纯度大于92.2%、99%的重组串联体A、B蛋白,并经透析复性法复性.Western印迹和间接ELISA显示纯化、复性后的重组蛋白与抗天然BoNT/A马血清有特异性结合反应.     

A cyclic peptide–polymer probe for the detection of Clostridium botulinum neurotoxin serotype A

A Botulinum neurotoxin serotype A (BoNT/A) ELISA detection system was developed based upon an 11-mer cyclic peptide, termed C11-019, that was identified through peptide phage display technology. The assay employs a sandwich format using the C11-019 cyclic peptide attached to a PEMA (poly(ethylene maleic anhydride)) matrix as the capture phase and anti-BoNT/A polyclonal antibodies as the detection phase. Results reported demonstrate that the C11-019 peptide–polymer can specifically bind to BoNT/A with no cross-reactivity to other serotypes examined in assay buffers and a variety of body fluids and foodstuffs. When a highly sensitive chemiluminescent substrate was engaged, the detection of 1 pg/mL could be readily achieved within 3 h with a linear range of 0.1–1 ng/mL. These results demonstrate that an inexpensive peptide–polymer-based capture ELISA system can be used for rapid, sensitive and highly specific BoNT detection.     

Increase in levels of total free fatty acids in rat brain regions following 3-nitropropionic acid administration

Acute exposure to a neurotoxin, 3-nitropropionic acid (3-NPA), in rats results in an increase in total free fatty acid (FFA) concentration in selective brain regions. We investigated the effect of 3-NPA administration on the cerebral concentrations of FFA used as a marker of oxidative stress. Rats (n=3/group) were dosed subcutaneously (s.c.) either with a vehicle (phosphate buffer) or 3-NPA in phosphate buffer at 30 mg/kg body weight. Animals were sacrificed after 1, 2, 3, and 6 h of injection. Brains were then dissected into frontal cortex (FC), caudate nucleus (CN), and hippocampus (HIP). The concentration of total FFA increased from 130 to 300% within 1–2 h after 3-NPA injection in all brain regions when compared with the baseline level obtained from the control rats and taken as 100%. In CN, FFA returned to the baseline level within 3 h of treatment. However, in FC and HIP the concentration of FFA remained significantly elevated above the baseline until 6 h. The released FFA provide a substrate for free radicals formation. The results of this study suggest a role of oxidative stress in the mechanism of 3-NPA toxicity.     

Binding of botulinum neurotoxin to pure cholinergic nerve terminals isolated from the electric organ of Torpedo

Summary Torpedo electric organ has been used to study the binding of botulinum neurotoxin type A to pure cholinergic synaptosomes and presynaptic plasma membrane.¹²⁵I-labeled botulinum neurotoxin type A exhibits specific binding to cholinergic fractions. Two binding sites have been determined according to data analysis: a high affinity binding site (synaptosomes: K_d=0.11±0.03 nM, B_max=50±10 fmol · mg prot^–1; presynaptic plasma membrane: K_d=0.2±0.05 nM, B_max=150±15 fmol · mg prot^–1) and a low affinity binding site (synaptosomes: K_d 26 nM, B_max 7.5 pmol · mg prot^–1; presynaptic plasma membrane: K_d 30 nM, B_max 52 pmol · mg prot^–1). The binding of¹²⁵I-botulinum neurotoxin type A is decreased by previous treatment of synaptosomes by neuraminidase and trypsin, and by a preincubation with bovine brain gangliosides or antiserum raised against Torpedo presynaptic plasma membrane. When presynaptic plasma membranes are blotted to nitrocellulose sheet, either¹²⁵I-botulinum neurotoxin or botulinum toxin-gold complexes bind to a M_r 140,000 protein. Botulinum toxin-gold complexes have also been used to study the toxin internalization process into Torpedo synaptosomes. The images fit the three step sequence model in the pathway of botulinum neurotoxin poisoning.     

神经生长因子偶联物对老年性痴呆动物模型的保护作用

目的　探讨神经生长因子偶联物 (NGF -Tf)对老年性痴呆 (AD)大鼠的影响 .方法　以手术切断大鼠双侧隔 -海马胆碱能通路的方法建立AD动物模型 ,每天从大鼠尾静脉注射NGF -Tf .通过水迷路试验观察大鼠的记忆和方向辨别能力 ;对海马和隔区行神经组织学检查 ;应用酶组织化学技术显示相应区域的ChAT ,采用计算机病理图像分析系统测定酶活性以判断其胆碱能功能状态 .结果　水迷路试验中 ,NGF -Tf组在 10s内抵达平台的正确反应平均数提高 (p <0 .0 5 ) .光镜下 ,NGF -Tf组隔区仅见轻微萎缩性改变 ,而模型组隔区萎缩性改变较明显 ,表现为神经元数目明显减少 ,细胞轮廓不清 ,有胶质细胞增生 ;正常对照组、NGF -Tf组和模型组的海马区未见明显病理性改变 .ChAT染色统计结果显示 ,正常对照组、NGF -Tf组大鼠的海马区及隔区IOD值与模型组比较 ,均有显著性差异 (p <0 .0 1) .结论　NGF -Tf能穿透血脑屏障 ,有效防止模拟AD病变的大鼠的基底前脑胆碱能神经元的变性和死亡 ,改善其记忆和方向辨别能力 ,促进其胆碱能神经元的功能恢复     

PCR 检测产 A、B、E、F 和 G 型肉毒神经毒素梭菌的神经毒素基因

肉毒神经毒素分为Ａ、Ｂ、Ｃ、Ｄ、Ｅ、Ｆ和Ｇ七个血清型，其中Ａ、Ｂ、Ｅ和Ｆ型引起人类肉毒中毒。为此，选取肉毒神经毒素的保守序列设计了一对简并引物，对１８株肉毒梭菌和８株相关梭菌进行了检测，表明该引物可特异扩增Ａ、Ｂ、Ｅ、Ｆ和Ｇ型肉毒梭菌及产Ｅ型肉毒神经毒素的丁酸梭菌，产物为２６４ｂｐ，敏感性达１０ｐｇ细菌ＤＮＡ。采有酚－氯仿抽提法、固相载体捕获法和热裂解法处理产毒菌株，结果表明热裂解法安全、简便、快速，所制模板扩增效果明显。因此，此ＰＣＲ方法可用于快速敏感地检测引起人类肉毒中毒的梭菌。     

Classical and alternative pathway complement activation are not required for reactive systemic AA amyloid deposition in mice

During induction of reactive systemic amyloid A protein (AA) amyloidosis in mice, either by chronic inflammation or by severe acute inflammation following injection of amyloid enhancing factor, the earliest deposits form in a perifollicular distribution in the spleen. Because the splenic follicular localization of immune complexes and of the scrapie agent are both complement dependent in mice, we investigated the possible complement dependence of AA amyloid deposition. In preliminary experiments, substantial depletion of circulating C3 by cobra venom factor had little effect on experimental amyloid deposition. More importantly, mice with targeted deletion of the genes for C1q or for both factor B and C2, and therefore unable to sustain activation, respectively, of either the classical complement pathway or both the classical and alternative pathways, showed amyloid deposition similar to wild type controls. Complement activation by either the classical or alternative pathways is thus not apparently necessary for the experimental induction of systemic AA amyloid in mice.     

眼镜蛇毒因子对豚鼠-大鼠异种心脏移植的影响

目的 :研究眼镜蛇毒因子 (CVF)对豚鼠 -大鼠非协调性异种心脏移植的影响 ,探讨其应用的可能性。方法 :给受者大鼠进行 CVF (16 0 μg/ kg)、CVF+ CYP(16 0 μg/ kg+ 2 0 m g/ kg)、CYP(2 0 mg/ kg)腹腔注射处理 ,耗竭其体内补体 ,随后对耗竭体内补体的受者大鼠进行颈部豚鼠 -大鼠异种心脏移植。测定移植供心的存活时间。结果 :经 CVF处理后移植供心存活时间获得延长至 (36 .3± 5 .1) m in。加用环磷酰胺 (CYP)延长尤为明显 [(5 3.4± 7.4) m in],CYP对移植供心存活时间也有一定的延长作用 [(31.7± 6 .0 ) min]。结论 :CVF可延长供心的存活时间 ,对非协调性异种心脏移植具有一定的应用价值。     

眼镜蛇蛇毒因子与大鼠中性白细胞吞噬功能减退的量效研究

:研究中华眼镜蛇的蛇毒因子(CVF)与中性白细胞吞噬功能的量效关系及CVF在非协调性异种心脏移植应用中的意义。方法:①用不同剂量的CVF腹膜腔内注射(i.p.)SD大鼠,测定大鼠血液中性白细胞噬菌率;②经CVFi.p.处理后大鼠进行颈部豚鼠—大鼠异种心脏移植,然后测定移植前后大鼠不同时点的血液中性白细胞噬菌率。结果:①CVF能使大鼠血液中性白细胞噬菌功能减退,并呈量效关系;②经CVF处理的大鼠移植后无发生超急排斥反应(HAR),且血液中性白细胞噬菌率明显减退,至术后3d内仍未恢复。结论:①CVF有抑制中性白细胞噬菌功能,且呈量效关系;②CVF可抑制非协调性异种心脏移植的HAR,测定中性白细胞噬菌功能是一种简便测定CVF体内抗补体活性的方法。