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BACKGROUND: The degree of neurofilament (NF) phosphorylation is closely correlated with the occurrence of Alzheimer disease (AD), and apolipoprotein E4 (apoE4) is a generally acknowledged liability factor for AD, but the effect and mechanism of apoE4 on the NF phosphorylation in neurons are not very clear. It has been reported that in the neurons cultured in vitro and in brain tissue of AD patients, the amino acid residues of apoE4 protein C terminal (272-299) could be truncated by hydrolysis,and produce truncated-apoE4 fragment. The latter interacts with the NF phosphorylation in neurofibrillary tangles (NFTs), which are the characteristic pathological changes of AD.OBJECTIVE: To observe the effect of truncated-apoE4 overexpression on the NF phosphorylation in the cultured neurons.DESIGN: A non-randomized controlled observation.SETTING: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: The experiment was carried out in the Laboratory of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology in December 2005. The mice neuroma cell strain N2a was provided by Dr. Xu.METHODS: The truncated-apoE4(△272-299) cDNA was subcloned into pEGFP-c3 to form pEGFP-T-apoE4 recombinant. Then pEGFP-c3, pEGFP-apoE4 and pEGFP-T-apoE4 were transfected into N2a cells by lipofectamine2000 respectively. NF phosphorylation was detected by Western blot assay. The activities of glycogen synthase kinase-3 (GSK-3) and cyclin-dependent kinase 5(CDK-5) were measured.MAIN OUTCOME MEASURES: The degree of NF phosphorylation and the activities of GSK-3 and CDK-5 were mainly observed.RESULTS: In the transfected groups, the contents of phosphorylated NF were significantly increased, the GSK-3 activities were significantly increased, which were the most significant in the pEGFP-T-apoE4 transfected group (P＜0.05), but the CDK-5 activities were not significantly different from that in th e control group (P＞0.05).CONCLUSION: These results indicate that in vitro overexpression of truncated-apoE4(△272-299) can lead to NF hyperphosphorylation by activating of GSK-3 but not CDK-5, which may be the underline mechanism of AD induced by truncated-apoE4(△272-299).

9.Experimental Studies on Acute Oral Toxicity, Skin Irritation and Skin Allergy of Thuja Essential Oil

Jin PENG ; Lu TANG ; Yan XIAO ; Yang CHEN ; Meihua BAO

China Pharmacist 2016;19(7):1420-1422

Objective:To evaluate the acute oral toxicity , skin irritation and skin allergy of Thuja essential oil ( TEO) , and pro-vide experimental basis for the clinical use of TEO .Methods:The acute oral toxicity was measured by Horn ’ s assay .Totally 40 KM mice were divided into four groups and intragastrically administered with TEO at different dose of 21.50, 10.00, 4.64 and 2.15 g · kg-1 .After the 14-day observation, the death number and toxic manifestations were recorded and observed , and LD50 was calculated by checking the Horn's form of LD50 .The skin irritation test was performed on healthy adult white rabbits .Totally 9 rabbits were divid-ed into 3 groups randomly , and TEO at the concentration of 100%, 50%and 25%was painted on the skin of the rabbits .Edible vege-table oil was used as the negative control .The erythema and edema of the treated skin were evaluated and scored .Delayed skin hyper-sensitivity reaction was used to investigate the allergy of TEO .Totally 30 white guinea pigs were randomly divided into 3 groups:TEO group, the negative control (edible vegetable oil) and the positive group (1%2, 4-dinitrochlorobenzene).After the intracutaneous in-duction stage and local induction stage , TEO was used to activate the hypersensitive reaction .The skin response was observed and scored after the 24-hour and 48-hour activation.Results:The mice in 21.50 g · kg-1 TEO treatment group were all dead , while only a part of the mice in 10.00 and 4.64 g · kg-1 TEO treatment groups were dead , and no mice died in 2.15 g · kg-1 TEO treatment group.According to the Horn's form of LD50 , LD50 of TEO was 9.26 g · kg -1 for male mice and 7.94 g · kg -1 for female mice.The results of skin irritation test indicated the strong irritation effects of TEO .However , the irritation of TEO was reduced after the dilution , and 25%TEO showed no irritation to the skin of rabbits .The results of delayed skin hypersensitivity reaction showed obvious erythema and edema induced by 2, 4-dinitrochlorobenzene , while no obvious erythema and edema were found in TEO treated guinea pigs , indi-cating non-allergic effect of TEO .Conclusion:TEO has strong skin irritation in rabbits , while no obvious oral toxicity in mice and skin allergy in guinea pigs .