Protective effect of paeonol on beta-amyloid 25-35- induced toxicity in PC12 cells**☆

BACKGROUND：Paeonol is a primary phenolic component of the Chinese medicinal herb Cortex moutan. Recent studies have shown that paeonol has anti-inflammatory, analgesic, and antioxidative effects as well as a significant cardioprotective effect against myocardial ischemia. OBJECTIVE： To investigate the protective effect of paeonol on β-amyloid 25-35-induced toxicity in PC12 cells and analyze its mechanism of action. DESIGN, TIME AND SETTING： A controlled repeated-measures cell-based study was performed in the Department of Pharmacology of Guangdong Medical College between September 2006 and December 2007. MATERIALS： Paeonol was supplied by Xuancheng Baicao Plant Industry and Trade Company, China. PC12 cells were a kind gift from Dr. Haitao Zhang at Guangdong Medical College. β-amyloid 25-35 was purchased from Sigma Company, USA. Lactate dehydrogenase （LDH） and malondialdehyde （MDA） kits were purchased from Nanjing Jiancheng Bioengineering Research Institute, China. METHODS： PC12 cells were maintained in Dulbecco＇s modified eagle＇s medium （DMEM） supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum at 37 ℃ and cultured in an incubator with 5% CO2. The medium was renewed every other day. Batches of cells were assigned into three groups. （1） Paeonol group： cells were preincubated with different concentrations of paeonol （12, 25 or 50 μmol/L） for one hour and β-amyloid 25-35 was added to the medium; （2） control group： cells were cultured in DMEM supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum; and （3） β-amyloid 25-35 group： β-amyloid 25-35 was added to the medium. MAIN OUTCOME MEASURES： When PC12 cells in each group were cultured for 24 hours, the cell viability was determined using the MTT reduction assay, LDH release into the culture media was measured by 2,4-dinitrophenylhydrazine chromatometry and MDA content was measured using a thiobarbituric acid assay. RESULTS： When PC12 cells wer     

Effect of Panax notoginseng saponins on the expression of beta-amyloid protein in the cortex of the parietal lobe and hippocampus, and spatial learning and memory in a mouse model of senile dementia

BACKGROUND： The pharmacological actions of Panax notoginseng saponins （PNS） lie in removing free radicals, anti-inflammation and anti-oxygenation. It can also improve memory and behavior in rat models of Alzheimer＇s disease. OBJECTIVE： Using the Morris water maze, immunohistochemistry, real-time PCR and RT-PCR, this study aimed to measure improvement in spatial learning, memory, expression of amyloid precursor protein （App） and β -amyloid （A β ）, to investigate the mechanism of action of PNS in the treatment of AD in the senescence accelerated mouse-prone 8 （SAMP8） and compare the effects with huperzine A. DESIGN, TIME AND SETTING： A completely randomized grouping design, controlled animal experiment was performed in the Center for Research ＆ Development of New Drugs, Guangxi Traditional Chinese Medical University from July 2005 to April 2007. MATERIALS： Sixty male SAMP8 mice, aged 3 months, purchased from Tianjin Chinese Traditional Medical University of China, were divided into four groups： PNS high-dosage group, PNS low-dosage group, huperzine A group and control group. PNS was provided by Weihe Pharmaceutical Co., Ltd. （batch No.： Z53021485, Yuxi, Yunan Province, China）. Huperzine A was provided by Zhenyuan Pharmaceutical Co., Ltd. （batch No.： 20040801, Zhejiang, China）. METHODS： The high-dosage group and low-dosage group were treated with 93.50 and 23.38 mg/kg PNS respectively per day and the huperzine A group was treated with 0.038 6 mg/kg huperzine A per day, all by intragastric administration, for 8 consecutive weeks. The same volume of double distilled water was given to the control group. MAIN OUTCOME MEASURES： After drug administration, learning and memory abilities were assessed by place navigation and spatial probe tests. The recording indices consisted of escape latency （time-to-platform）, and the percentage of swimming time spent in each quadrant. The number of A β 1-40, A β 1-42 and App immunopositive neurons in the brains of SAMP8 mice w     

Generation and characterization of a novel single-chain antibody fragment specific against human fibrin clots from phage display antibody library

A novel single-chain fragment variable (scFv) antibody was developed directed against human fibrin clots by using the human single fold scFv libraries I+J (Tomlinson I+J). Three positively binding scFvs were evaluated by scFv-phage enzyme-linked immunosorbent assay (ELISA) and DNA sequencing. Then the positive scFv was expressed in soluble form in Escherichia coli HB2151 and purified by immobilized metal affinity chromatography (IMAC) with a yield of about 1 mg/l, the expression of soluble scFv was verified by Western blot analysis. The purified scFv could specifically recognize human fibrin clots and indicate no binding ability with human fibrinogen shown by ELISA. Furthermore, we will amplify the gene of the positive scFv by polymerase chain reaction (PCR) for future study of its role in diagnosis and therapy of thrombus-correlated diseases.     

抗乙酰胆碱受体单链抗体基因克隆与表达

目的重建含有抗乙酰胆碱受体(AChR)单链抗体1929#(single-chain Fv antibody 1929#,scFv1929#)基因的载体并在大肠杆菌(E.coli)进行表达,提高scFv1929#的可溶性表达量。方法用聚合酶链反应法(PCR)扩增载体pHEN1中的scFv1929#结构基因,将扩增产物定向克隆至载体pET32a(+)的多克隆位点中构建新的载体pET32a(+)-scFv1929#,经EcoR v和NotⅠ双酶切后进行鉴定,并将所构建载体转化入表达宿主E.coli BL21(DE3)plysS菌株内诱导表达后集菌并裂菌,将诱导前菌体、诱导后菌体,以及裂菌后所得诱导后上清、诱导后沉淀进行十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)分析,并采用Western blot(WB)法进行鉴定。结果鉴定结果显示载体pET32a(+)-scFv1929#中所插入的scFv1929#基因片段大小为730bp,与预计相符,经测序确定该基因序列无误。SDS-PAGE电泳结果显示37℃下诱导前菌体、诱导后菌体、诱导后上清、诱导后沉淀中均可在相对分子质量(Mr)接近44 000处见到蛋白条带,其中诱导后菌体及诱导后沉淀中的条带较粗大。经WB法证实融合蛋白scFv1929#具有较高特异性。结论 scFv1929#表达载体pET32a(+)-scFv1929#被成功构建,并可在大肠杆菌中高效表达,其表达产物具有较好特异性。     

Fusion protein of single-chain variable domain fragments for treatment of myasthenia gravis

Single-chain variable domain fragment(scFv)637 is an antigen-specific scFv of myasthenia gravis.In this study,scFv and human serum albumin genes were conjugated and the fusion protein was expressed in Pichia pastoris.The affinity of scFv-human serum albumin fusion protein to bind to acetylcholine receptor at the neuromuscular junction of human intercostal muscles was detected by immunofluorescence staining.The ability of the fusion protein to block myasthenia gravis patient sera binding to acetylcholine receptors and its stability in healthy serum were measured by competitive ELISA.The results showed that the inhibition rate was 2.0–77.4%,and the stability of fusion protein in static healthy sera was about 3 days.This approach suggests the scFv-human serum albumin is a potential candidate for specific immunosuppressive therapy of myasthenia gravis.     

抗NI-35重组单链抗体基因cDNA的合成与克隆

目的抗NI-35抗体(anti-NI-35antibody)作为神经再生抑制因子(NI-35)的拮抗剂对神经再生促进作用的研究是近年的热点,研究表明,抗NI-35抗体能促进体内外受损伤神经元的存活和突起生长。我们重新设计并人工合成抗NI-35重组单链抗体(anti-NI-35-scfv)的cDNA克隆构建其表达载体,在原核系统中实现初步表达。方法参照genebank中发表的抗NI-35抗体的轻链重链序列,重新设计适于在大肠杆菌中表达的目的基因片段,将该基因双链分成35个小片段合成,经退火、复性连接成目的片段后,克隆到经过BamHI和HindIII双酶切的克隆载体pUC18中,并转化大肠杆菌DH5a,抽提重组子pUC18/744进行克隆PCR、酶切鉴定及测序分析。结果测序结果证明获得的基因序列与实验设计仅差一个碱基。结论正确合成了抗NI-35重组单链抗体(anti-NI-35-single-chainantibody)为抗NI-35抗体应用于治疗弥漫性轴索损伤提供了实验基础。     

Screening and characterization of human single-chain Fv antibody against beta-amyloid peptide 40

Expression of single-chain variable fragment antibody on the surface of filamentous bacteriophage is widely used to make antibodies with pre-defined specificities. Using direct selection on solid phase-bound amyloid-beta 40 peptide, which is a main pathogenic feature of Alzheimer's disease, we obtained single-chain Fv antibody with specific binding activity. The binding epitope of the antibody is located between amino acids 1 and 16 of the peptide antigen. DNA sequencing showed that the gene coding for the single chain Fv antibody consists of 768 bp, and the complementarity-determining regions were deduced.     

Hyperhomocysteinemic Alzheimer's mouse model of amyloidosis shows increased brain amyloid beta peptide levels

Recent epidemiological and clinical data suggest that elevated serum homocysteine levels may increase the risk of developing Alzheimer's disease (AD), but the underlying mechanisms are unknown. We tested the hypothesis that high serum homocysteine concentration may increase amyloid beta-peptide (Abeta) levels in the brain and could therefore accelerate AD neuropathology. For this purpose, we mated a hyperhomocysteinemic CBS(tm1Unc) mouse carrying a heterozygous dominant mutation in cystathionine-beta-synthase (CBS*) with the APP*/PS1* mouse model of brain amyloidosis. The APP*/PS1*/CBS* mice showed significant elevations of serum homocysteine levels compared to the double transgenic APP*/PS1* model of amyloidosis. Results showed that female (but not male) APP*/PS1*/CBS* mice exhibited significant elevations of Abeta40 and Abeta42 levels in the brain. Correlations between homocysteine levels in serum and brain Abeta levels were statistically significant. No increases in beta secretase activity or evidence of neuronal cell loss in the hyperhomocysteinemic mice were found. The causes of neuronal dysfunction and degeneration in AD are not fully understood, but increased production of Abeta seems to be of major importance. By unveiling a link between homocysteine and Abeta levels, these findings advance our understanding on the mechanisms involved in hyperhomocysteinemia as a risk factor for AD.     

Intranasal delivery of ESBA105, a TNF-alpha-inhibitory scFv antibody fragment to the brain

Intranasal drug administration is an attractive route for targeted delivery of large molecular weight compounds to the central nervous system (CNS). The purpose of this study was to assess the feasibility of this non-invasive application method in mice, for delivery of ESBA105, a TNF-alpha inhibitory single-chain antibody fragment (scFv) with a molecular weight of 26.3 kDa, to the brain. Pharmacokinetic parameters were determined for different brain regions (olfactory bulb, cerebrum, cerebellum, brain stem) and for serum, following both, intranasal and intravenous administrations of 400 μg and 40 μg ESBA105, respectively. ESBA105 efficiently migrated from the nasal cavity to the brain and maximum ESBA105 concentrations (C_max) in the brain were measured between 1.1 and 12.2 μg/mg of the total protein. Although a 10-fold higher dose was given intranasally, systemic exposure was about 33-fold lower for the intranasal route than following systemic application. Addition of a penetration enhancing peptide to the formulation enhanced the delivery of ESBA105 to the olfactory bulb and the cerebrum, without increasing systemic exposure.