A low calcium medium developed for epidermal keratinocytes were prepared according to the MCDB 153 modified formula and used in human epidermal keratinocyte culture compared with DMEM culture system. The observation by contrast microscopy and electron microscopy showed that in the low calcium medium keratinocytes grew as a monolayer of high proliferation and had many characteristics of basal cells, with a more rounded shape and large intercellular spaces. Increasing the calcium ion concentration in the medium or changing the other culture conditions the cells in these cultures could be induced stratification and terminal differentiation. The results suggest that the growth, proliferation and differentiation of cultured human epidermal keratinocytes can be controlled and regulated someway.

Citrulline which is a nonprotein amino acid,synthesizes the peptide bond,but it is not incorporated into proteins. It's used to be known as no point, but there is a difficult result that citrulline is related to many diseases in recent research.Citrulline is a biomaker in gastrointestinal injury,a supplement of arginine in arginine deficiency patients,and the evidence of sepsis.Citrulline,as an antigen among the process of its creation ,is one of the nosogenesis of rheumatoid arthritis,and checking the antibodies of citrulline is effective in diagnosing the rheumatoid arthritis early. Citrulline is also meaningful in diagnosing and treatment of some unfrequent diseases. Citrulline is widely used.