Blood brain barrier is the main obstacle for drug delivery to the brain.To overcome the limited access of drugs to the brain,three methods have been developed at present:neurosurgical-based strategies,chemistry-based strategies to increase the lipid solubility of the drug,and biology-based strategies of endogenous BBB transporters-mediated drug delivery.PTD transport system to delivery drug across BBB is an emerging technology,which conveniently and efficiently deliver various molecules into spinal cord and brain via blood,intraperitoneally etc.PTD transport system offers a new approach to central nervous system disease with quick,convenient and safe charcteristics.

Some basic nuclear localization signals(NLS) have the capability of penetrating cell membrane and deliverying recombinant proteins, DNA, oligonucleotide into living cells. NLS based delivery system prohaps can satisfy most of major requirement in cargoing exogenous macromolecules or charged compounds. Different internalization mechanisms were found for different NLSs. Endocytosis or electrostatic binding of the anionic membranes and cationic NLSs probably induce celluar uptake.

Aim To determine TAT-Tcntf penetration ability and to investigate the effects of the fusion protein on SH-SY5Y cells against toxicity induced by β-amyloid peptide 25-35(Aβ_(25-35) ).Methods The conjugate(TAT-tCNTF)of TAT(47-57)of HIV-1 and the truncated human CNTF active fragment was genetic engineered and expressed in E.Coli.Immunofluorescence was used to identify cell permeation ability across membrane.MTT assay was used to measure the survival of SH-SY5Y cells injured by Aβ_(25-35).And Hoechst 33342/PI double staining was used to observe the morphology of cell apoptosis and necrosis.LDH was measured by spectrophotometric method.Results The expression vector of pBV220-TAT-tCNTF was constructed successfully.Western blot showed the recombinant fusion protein could bind specifically with CNTF antibody.The immunofluorescence assay clearly demonstrated that TAT-tCNTF did penatrate into the cells while little rhCNTF pass across the cells.Double staining and LDH release assay demonstrated that TAT-tCNTF could promote significantly the survival of the cells.Conclusion sTAT-tCNTF with high activities and effective transmembrane ability is obtained for the first time.The fusion protein protects SH-SY5Y cells from death after Aβ25-35 exposure.

Aim To determine TAT-tCNTF penetration ability and to investigate the effects of the fusion protein on SH-SY5Y cells against toxicity induced by ?-amyloid peptide 25-35(A?25-35 ).Methods The conjugate(TAT-tCNTF)of TAT(47-57)of HIV-1 and the truncated human CNTF active fragment was genetic engineered and expressed in E.Coli.Immunofluorescence was used to identify cell permeation ability across membrane.MTT assay was used to measure the survival of SH-SY5Y cells injured by A?25-35.And Hoechst 33342/PI double staining was used to observe the morphology of cell apoptosis and necrosis.LDH was measured by spectrophotometric method.Results The expression vector of pBV220-TAT-tCNTF was constructed successfully.Western blot showed the recombinant fusion protein could bind specifically with CNTF antibody.The immunofluorescence assay clearly demonstrated that TAT-tCNTF did penatrate into the cells while little rhCNTF pass across the cells.Double staining and LDH release assay demonstrated that TAT-tCNTF could promote significantly the survival of the cells.Conclusions TAT-tCNTF with high activities and effective transmembrane ability is obtained for the first time.The fusion protein protects SH-SY5Y cells from death after A?25-35 exposure.

The mode of action of V-type organophosphate poisons on acetylcholinesterase has been studied. It shows that the leaving group of V-type poisons is dialkylamino-ethyl-thio radical,and the phosphonyla-ting site on the enzyme molecule is similar to that of the G-type poison soman, as shown by the competition experiments.

OBJECTIVEInhibition of acetylcholinesterase (AChE) in human brain caused by phoxim or phoxim oxon, their reactivation with oxime and aging of phosphorylated AChE were studied and compared in vitro.

METHODSMicro-colorispectrophotometric assay was used to determine the activity of AChE.

RESULTSThe pI(50) of inhibition of AChE in human brain by phoxim and phoxim oxon were 5.39 and 5.77, respectively, whereas the pI(90) were 4.60 and 5.00, respectively. The reactivation rate of 0.1 mmol/L of pralidoxime (2-PAM), obidoxime (LüH(6)), trimedoxime (TMB-4) and pyramidoxime (HI-6) for phoxim-inhibited AChE in human brain was 65%, 97%, 91% and 56%, respectively, and their reactivation rate for phoxim oxon-inhibited AChE in human brain was 97%, 87%, 99% and 89%, respectively. The optimal reactivator for phoxim and phoxim oxon-inhibited AChEs was LüH(6) and TMB-4, respectively. The half aging time of phoxim and phoxim oxon inhibited phosphorylated AChEs were 39 and 28 hours, respectively, and the 99% aging time were 256 and 186 hours, respectively.

CONCLUSIONSLüH(6) or TMB-4 should be used at the earlier as possible after poisoning with phoxim and phoxim oxon, and the reactivator should be consecutively used for more than seven days, even after their acute symptoms have been well controlled.

Acetylcholinesterase ; metabolism ; Brain ; drug effects ; enzymology ; Cholinesterase Inhibitors ; pharmacology ; Cholinesterase Reactivators ; pharmacology ; Enzyme Stability ; Humans ; In Vitro Techniques ; Obidoxime Chloride ; pharmacology ; Organothiophosphorus Compounds ; pharmacology ; Oximes ; pharmacology ; Paraoxon ; pharmacology ; Pralidoxime Compounds ; pharmacology ; Time Factors ; Trimedoxime ; pharmacology