Objective To investigate the effects of low doses 147Pm internal irradiation against hereditary mutation in mouse cells induced by subsequent high dose of 147Pm irradiation. Methods The frequencies of micronucleated polychromatic erythrocytes (mn-PCE) micronucleated normochromatic erythrocytes (mn-NCE) and chromosome aberration in bone marrow and peripheral blood cells were observed. Results The frequencies of nm-PCE、mn-NCE and chromosome aberration induced by high dose of 147Pm irradiation showed a highly significant increase over the control at 24 h after irradiation (P＜0.05 or 0.01).However, the frequencies in cells pre-exposed to 0.37-37 Bq/g of 147Pm were decreased significantly (P＜0.05 or 0.01),as compared with those of the group without pre-exposure. Conclusion Low doses of in vivo 147Pm β-irradiation can induce a radioadaptive response of the lymphocytes and erythroblasts.The induction of the adaptive response has a wide dose range.The mn-PCE and mn-NCE are more sensitive indexes for revealing biological effects of radiation as compared with the chromosome aberration.

Aim To study the expression of β-NGF gene in the mammlian cells and the biological activity of its expression products. Methods The β-nerve growth factor (β-NGF) cDNA which obtained from the plasmid pGEM-β-NGF by enzyme digestion analysis was cloned into the expression vector pcDNA3 to construct the recombinant plasmid pcDNA3-β-NGF. COS-7-cell line grown to log phase was transfected using lipofectamine reagent. The expression level of β-NGF mRNA and the biological activity were analyzed by Northern blot and observation of neurite outgrowth of PC12 cell line stimulated by supernatant, respectively. Results The β-NGF gene was expressed successfully in COS-7 cell lines. The culture supernatant of the positive COS-7 cells transfected with pcDNA3-β-NGF could stimulate the neurite outgrowth of PC12 cell line. Conclusion The target gene expressed successfully in the transfected COS-7 cell line and had good biological activity.

To test the hypothesis that the controlled reperfusion of warm blood cardioplegiacontaining mannitol would result in more effectively improved recovery of myocardial function by prevent-ing or reducing a potentially harmful component of reperfusion. Methods: Thirty-two cats were divided in-to four groups. Group Ⅰwas not subjected to ischemia or reperfusion injury. Group Ⅱ was subjected to60 min hypothermic ischemia. Group Ⅲwas subjected to 60 min hypothermic ischemia and 60 min reperfu-sion. Group Ⅳ was controlled reperfusion with warm blood cardioplegia containing mannitol. Results:Myocardial functlon was significantly depressed after 60 min reperfusion- Increased myocardial water con-tent and low ATP c0ntent were observed also. Controlled reperfusion with warm bl0od cardioplegia con-taining mannitol was helpful to improve the recovery of myocardial function and ATP content, and to re-duce the myocardial water content. Conclusion: These results indicate that controlled reperfusion after is-chemia provides benefit in avoiding myocardium from reperfusion injury.