ABSTRACT
Objective To evaluate the biological toxicity of heavy metals by using Caenorhabditis elegans. Methods The C. elegans at L4 stage were exposed to CdCl2 CrCl3 As2O3 PbCl2 HgCl2 with low concentrations and M9 buffer the control group for 72 h respectively and the effects of heavy metals with different concentrations on the survival time and reproduction of C. elegans were evaluated. Results After exposure to 2.5 10μmol/L HgCl2 and PbCl2 10μmol/L CdCl2 and 50μmol/L CrCl3 for 72 h respectively the life spans and survival curves of the C. elegans were different from those in the control group the differences were statistically significant all P<0.05 . After exposure to CdCl2 CrCl3 As2O3 PbCl2 and HgCl2 with the con?centrations of 2.5 50 100μmol/L for 72 h respectively the generational time and brood size of C. elegans were all different from those in the control group all P<0.01 . Among the 5 heavy metals at low concentrations the reproduction toxicity of Hg was bigger than Pb Cd Cr and the toxicity of As was the weakest. Conclusion Heavy metal exposure can affect the life span and reproductive toxicity of C. elegans.
ABSTRACT
Objective To evaluate the application effect of‘incorrect cases’in medical statis-tics teaching. Methods The junior students (n=307)of clinical medicine were selected as research subjects by random cluster sampling. They were divided into the teaching improving group (n=151) who accepted case teaching and control group (n=156)who accepted traditional teaching. At the end of the term,the teaching effect was surveyed by questionnaires and compared between the two groups. Measurement data was analyzed by t test,enumeration data by χ2 test and ranked data by rank sum test. Results Students' interests of medical statistics and understanding the importance of the course in teaching improving group were significantly higher than that in control group (Z=-2.375,P=0.018;Z=-2.971,P=0.003). The proportion of students with learning difficulties in teaching improving group was obviously lower than that in control group (Z=-2.488,P=0.013). The satisfaction with theory and practical teaching in teaching improving group (84.10% and 88.74%,respectively)was significantly higher that in control group (73.08%and 71.79%,respectively)(χ2=5.530,P=0.013;χ2=13.841,P<0.001). Although no difference was observed in the test score between the two groups (t=1.230,P=0.220),knowledge of parameter estimation,hypothesis testing and science research design in teach-ing improving group was significantly higher than that in control group (χ2=6.829,P=0.009;χ2=5.835, P=0.016). Conclusions Application of ‘incorrect cases’in medical statistics teaching could arouse students' learning interests and improve clinical medical students' comprehensive analy sis ability of medical statistics.
ABSTRACT
Objective To explore the risk factors of cerebral schistosomiasis japonica. Methods A total of 37 confirmed cases,diagnosed during 1999-2004 in Anhui Province,were involved in the study as case group. Three controls for each case were selected from the general population either without schistosomiasis,with chronic schistosomiasis or with acute schistosomiasis. The relevant risk factors on the disease were analyzed. Results Four factors with labour intensity, physical, economical and nutritional conditions before illness between case group and normal control group, 7 factors including epilepsy history, hypersensitivity,intensity and times of infection between case group and acute schistosomiasis control group,10 factors including intensity of infection,times of infection and treatment between case group and chronic schistosomiasis control group, all showed statistical significance (p