Objective To observe the effects of 860 MHz microwave radiation on an established dual task model of trace and delay eyeblink conditioning in guinea pigs.Methods Twenty-four guinea pigs with an established dual task model of trace and delay eyeblink conditioning were assigned randomly into four groups : a microwave-exposed 1 h group, a microwave-exposed 20 min group, a sham-exposed group and a normal control group.The guinea pigs in the 1 h and 20 min groups were irradiated on the head daily for 3 days using 860 MHz electromagnetic radiation at a power density of 1 mW/cm2 for 1 h and for 20 min, respectively. After radiation the guinea pigs were trained with classical dual task eyeblink conditioning.Results Compared with the normal control group, the behavioral parameters (acquisition rate and peak amplitude of trace and delay eyeblink) of guinea pigs in the microwave-exposed 1 h group had decreased significantly with no obvious change in latency. The behavioral parameters of guinea pigs in the microwave-exposed 20 min group, the sham-exposed group and the normal control group showed no obvious change.Conclusions Microwave radiation at 860 MHz and 1.0 mW/cm2 for 1 h can cause changes in dual trace and delay eyeblink conditioning in guinea pigs and decrease learning and memory capacity.

Objective To observe and analyze the role of different subfields of medial prefrontal cortex (mPFC) in the expression course of startle reflex.Methods 24 healthy male British kind of albino guinea pigs were randomly divided into 4 groups:anterior cingulated cortex lesion ( n =6) and sham-lesion ( n =6) ( Experiment 1 ) ; prelimbic cortex lesion/joint lesion of prelimbic cortex and anterior cingulated cortex(n=6) and sham-lesion ( n =6) ( Experiment 2 ).The animals were injected lidocaine ( lesion ) or physiological saline ( sham-lesion ).Each group received paired training of conditioned stimulus( CS,a tone) and unconditioned stimulus (US,a air puff),to observe the acoustic startle reflex(ASR) change of these groups.Results As the results of experiment 1 suggested,SR rate did not change significantly after anterior cingulated cortex lesion ( time effect:F =15.421,P =0.098 ; group effect:F =14.753,P =0.084).As the results of experiment 2 suggested,SR rate did not change significantly after prelimbic cortex lesion ( time effect:F =14.975,P =0.178 ; group effect:F =18.643,P =0.089).When prelimbic cortex and anterior cingulated cortex were lesioned at the same time,SR rate declined significantly and didn ' t recover with the following training ( group effect:F =67.743,P =0.009 ).ConclusionLesions of the prelimbic cortex and anterior cingulated cortex in mPFC cause the significantly decline of acoustic startle reflex( ASR),which don' t recover with the following training.This study indicates that mPFC involves in the regulation of ASR,but the regulation mechanism needs to be discussed.

Objective To explore Chongqing migrant workers Suiqian children′s mental health status and related factors .Meth-ods In this study 740 children from grade 7 to grade 9 in 3 schools which specify recruit migrant workers′children ,including the 399 migration children of migrant workers and 341 urban household registration students were involved .They were investigated with symptom rating scale(SCL-90) and self-made general questionnaire .Results There were no significant differences in SCL-90 scores between the migrant workers migration children group and urban household registration students group (P>0 .05) .Conclu-sion Generally speaking ,Chongqing migrant workers Suiqian children′s mental health status is good ,but there are still some prob-lems .We need do some further study on the mode of psychological intervention to maintain their physical and mental health .

Background The benchmark dose (BMD) method calculates the dose associated with a specific change in response based on a specific dose-response relationship. Compared with the traditional no observed adverse effect level (NOAEL) method, the BMD method has many advantages, and the 95% lower confidence limit of benchmark dose lower limit (BMDL) is recommended to replace NOAEL in deriving biological exposure limits. No authority has yet published any health-based guideline for rare earth elements. Objective To evaluate genotoxicity threshold induced by acute exposure to neodymium nitrate in mice using BMD modeling through micronucleus test and comet assay. Methods SPF grade mice (n=90) were randomly divided into nine groups, including seven neodymium nitrate exposure groups, one control group (distilled water), and one positive control group (200 mg·kg⁻¹ ethyl methanesulfonate), 10 mice in each group, half male and half female. The seven dose groups were fed by gavage with different concentrations of neodymium nitrate solution (male: 14, 27, 39, 55, 77, 109, and 219 mg·kg⁻¹; female: 24, 49, 69, 97, 138, 195, and 389 mg·kg⁻¹) twice at an interval of 21 h. Three hours after the last exposure, the animals were neutralized by cervical dislocation. The bone marrow of mice femur was taken to calculate the micronucleus rate of bone marrow cells, and the liver and stomach were taken for comet test. Results The best fitting models for the increase of polychromatophil micronucleus rate in bone marrow of female and male mice induced by neodymium nitrate were the exponential 4 model and the hill model, respectively. The BMD and the BMDL of female mice were calculated to be 31.37 mg·kg⁻¹ and 21.90 mg·kg⁻¹, and those of male mice were calculated to be 58.62 mg·kg⁻¹ and 54.31 mg·kg⁻¹, respectively. The best fitting models for DNA damage induced by neodymium nitrate in female and male mouse hepatocytes were the exponential 5 model and the exponential 4 model, respectively, and the calculated BMD and BMDL were 27.15 mg·kg⁻¹ and 11.99 mg·kg⁻¹ for female mice, and 16.28 mg·kg⁻¹ and 10.47 mg·kg⁻¹ for male mice, respectively. The hill model was the best fitting model for DNA damage of gastric adenocytes in both female and male mice, and the calculated BMD and BMDL were 36.73 mg·kg⁻¹ and 19.92 mg·kg⁻¹ for female mice, and 24.74 mg·kg⁻¹ and 14.08 mg·kg⁻¹ for male mice, respectively. Conclusion Taken the micronucleus rate of bone marrow cells, DNA damage of liver cells and gastric gland cells as the end points of genotoxicity, the BMDL of neodymium nitrate is 10.47 mg·kg⁻¹, which can be used as the threshold of genotoxic effects induced by acute exposure to neodymium nitrate in mice.