Objective To establish an efficiency calibration method without a radioactive source for Inspector 2000 gamma spectroscopy system.Methods At the fwst step,geometry parameters of the detector were properly specified by comparisons of FEPE(Full Energy Peak Efficiency)between Monte Carlo(MC)calculations and the average measured values of HPGe and NaI detectors using point sources(137 Cs).The differences between calculations and measurements were generally within ±10% for gamma rays.Then,Monte Carlo simulation was used to evaluate the counting efficiency of Nal(TI)and HPGe detectors for BOMAB phantoms.Corresponding efficiency curves and functions were fitted.Results The counting efficiency received from the fitted efficiency functions had a good agreement with those from MC simulation.The bias for Nal detector ranged from-19% to 18%,while the bias for HPGe detector ranged from-11% to 17%.The above errors were totally acceptable in the on-site deployment during nuclear and radiological emergency events.Conclusions Monte Carlo method is simple,time and laborsaving in determing the counting efficiency of gamma spectroscopy system.

BACKGROUND: Secretion of various neurotrophic factors by Schwann cells plays important roles in neural regeneration. However, the secretion capability is affected by many factors. To seek a feasible method for promoting nerve growth factor secretion by Schwann cells is a key of regeneraion following neurologic defect.OBJECTIVE: To explore the effects of methylprednisolone(solu-medrol) on the secreted function of Schwann cells of cultured rats.METHODS: Schwann cells were isolated and cultured by enzyme digestion method. Cell growth was observed under an inverted phase contrast microscope. Following passage, purity of some Schwann cells was identified using S-100 protein immunity. Other Schwann cells were regulated using cell counting plate into 1×10~9/L, and incubated in a 6-well culture plate (15 wells) for further incubation. Following 4 days of culture, different concentrations of solu-medrol (10~(-3), 10~(-4), 10~(-6), 10~(-8) mol/L) were administrated to the cell, while blank control group (1 well) was given no drug. 24, 48 and 72 hours after administration, reverse trancription-polymerase chain reaction (RT-PCR) was used in the detection of the levels of nerve growth factor mRNA.RESULTS AND CONCLUSION: Number of primarily cultured cells was significantly increased at day 7, and 80% cells were confluent. Subcultured cells were spindle-shaped, with 2 thin long processes, showing positive fluorescence staining. Fibroblasts were round or flat, showing negative reaction of fluorescence staining. Reserve transcription-polymerase chain reaction demonstrated that nerve growth factor number at 72 hours affected by 10~(-8) mol/L radiosone was increased compared with the blank control group and other concentrations and other time points (P < 0.05). Number of nerve growth factor was reduced following treatment of 10~(-3) mol/L radiosone compared with the blank control group and other concentrations (P < 0.05). These results suggested that high concentration of solu-medrol prohibits secreted function of Schwann's cells, but long time and low dosage solu-medrol promotes secreted function of Schwann's cells.

ObjectiveTo evaluate the efficacy of mini-incisional double-tsuge suture method with 0-0 absorbable polydioxanone-cord (PDS-Ⅱ)in repair of acute achilles tendon rupture.MethodsA total of 34 patients were subjected to acute closed achilles tendon ruptures,including 25 males and 9 females at a mean age of 32 years ( range,20-45 years).Injury causes included sports injuries in 27 patients,falling injuries in six and heavy object impingement injury in one.The time from injury to operation was average 3 days (range,1-6 days).All patients underwent minimally invasive repair with double-tsuge suture method by using PDS-Ⅱ.The ankle joint was fixed with short leg plaster cast at 30° plantar flexion position and the cast was removed six weeks later to take functional exercise.The patients could walk with full weight-bearing 8-10 weeks later and could gradually return to activity 3-4 months later.Results There was one patient with poor incision healing and one patient with reflex sympathetic dystrophy postoperatively.The rest patients had stage Ⅰ incision healing without skin adhesions.No complications such as infection,lower extremity deep venous thrombosis or sural nerve injury occurred postoperatively.All the patients received follow-up of 12-24 months (average 15 months),which showed no complications like tendon rerupture occurred.According to clinical evaluation criterion of Termann,the average score was 92 points (range,76-96 points).The result was excellent in 28 patients,good in five and fair in one,with excellence rate of 97％.ConclusionsSmall incisional double-tsuge suture method achieves low rate of complications and good outcomes for repairing acute achilles tendon rupture and is an ideal tendon surgery approach.

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.