ABSTRACT
Objective@#To evaluate the occupational health risk of key posts exposed to cement dust in four cement production enterprises, and to provide reference for cement pneumoconiosis prevention and control. @*Methods@#Four Chinese typical cement enterprises and key posts exposed to cement dust were selected to carry out occupational health investigation and detection, and three risk assessment methods were used to assess their occupational health risk levels, including semi-quantitative comprehensive index method, semi-quantitative contact ratio method and risk rating method of International Mining and Metal Commission ( ICMM ). Meanwhile, the differences and consistencies among different assessment methods were compared. @*Results@#Dust free silica content ranged from ( 4.70±2.01 ) % to ( 5.63±2.48 ) %,and the total and respirable dust concentrations exposed by bagged cement loaders and cement baggers exceeded Chinese permissible concentration-time weighted average（ PC-TWA ）. The results of semi-quantitative comprehensive index method showed that all the types of work were at high risk of total and respirable dust, while the results of the other two assessment methods showed that bagged cement loaders and cement baggers were at a extremely high or intolerable risk. There were no significant differences among three risk assessment methods whether in terms of total dust or respirable dust ( P>0.05 ). ICMM risk rating method and contact ratio method showed highly positive correlation in term of respirable dust ( rs=0.894, P=0.016 ), but not in term of total dust ( rs=0.733, P=0.097 ). However, the correlations of comprehensive index method with the other two methods were unable to conduct.@*Conclusion@#Bagged cement loaders and cement baggers are at high occupational health risk levels. Moreover, semi-quantitative contact ratio method and ICMM risk rating method have high positive correlation in term of respirable dust, the applicability of comprehensive index method still needs further study.
ABSTRACT
Skeletal muscle development is regulated by Six1, an important myogenic transcription factor. However, the functional analysis of duck Six1 has not been reported. Here, we cloned the coding domain sequence (CDS) region of the duck Six1 gene using RT-PCR and RACE methods. Bioinformatics analysis revealed that duck Six1 CDS region comprised of 849 bp and encoded 282 amino acids and had a high degree of homology with other species, suggesting that the functions of duck Six1 gene are conserved among other animals. Real-time PCR used to determine the mRNA expression profiles of duck Six1 in different tissues and different developmental stages showed that Six1 was highly expressed in skeletal muscle and the embryonic stage. Furthermore, the eukaryotic expression vector pEGFP-duSix1 was constructed and transfected into the duck myoblasts; the MTT assay revealed an obvious increase of cell proliferation after transfection. The expression profiles of Six1, Myf5 and MyoD showed that their expression levels were significantly increased. These results together suggested that pEGFP-duSix1 vector was constructed successfully and overexpression of duck Six1 in the myoblasts could promote cell proliferation activity and significant up-regulate expression of Myf5 and MyoD.