Objective To explore the effect of folic acid on neural stem cells(NSCs) proliferation from fetal rats in vitro.Method NSCs were isolated and cultured by microdissection,mechanical blowing and serum-free suspension culture,and identified by immunofluorescent staining using antibody against nestin.BrdU(5’bromo-2’deoxyuridine) was used to mark dividing neural stem cells.Cultured NSCs were divided into four groups:control group,low,high dose group(liquid media with added 4,40 mg/L folic acid),and deficiency group(liquid media with added 0.4 mg/L methotrexate,MTX).Monotetrazolium(MTT) and double-label immunofluorescence technique detected NSCs proliferation under the condition of folic acid.Results In the serum-free suspension medium,neurospheres that consisted of a great number of nestin-positive cells could be obtained.The proliferative ability of NSCs were observed by BrdU labeling methods.MTT assay and double-label immunofluorescence for nestin+BrdU showed that the growth tendency was increased with folate concentration in the medium.Compared with control group,NSCs growth rate of folate group was significantly increased in vitro.Conclusion The culture of NSCs isolated from fetal rats possesses the abilities of proliferation and self-regeneration.Folic acid may stimulate proliferation of NSCs efficiently.

Objective To calculate the electric field intensity and transmembrane voltage of spherical cells and ellipsoi -dal red blood cells ( RBC) in an extremely low frequency electromagnetic field .Through this calculation , we can provide reference to the search for interaction targets and mechanics between the extremely low frequency electromagnetic field and organisms.Methods The Finite Element Method was used in the numerical computation for the spherical cell model and the ellipsoidal RBC model .Results The electric field intensity of the two types of cells on the cellular membrane was both significantly higher than the applied electric field strength , and the values of the induced field strength and transmembrane voltage varied with the direction of the electric field periodically .Conclusion The cell shape and direction of the applied electric field are not the main determinants of the cellular membrane electric field intensity and the transmembrane voltage compared with electromagnetic parameters .The distribution of the electric field intensity and transmembrane voltage are re-lated to the direction of the applied electric field.