Objective To study the protein expression levels of matrix metalloproteinases (MMPs)and their inhibitors in bone tissues of rat femoral head and to explore the relationship between necrosis of femoral head and glucocorticoid.Methods Twenty healthy adult SD rats were randomly divided into glucocorticoid group and control group,with 10 rats in each.Glucocorticoid group was treated with intramuscular injection of hydrocortisone twice a week.The control group received normal saline of the same volume.Four weeks later,bone tissues of left femoral head were collected from each group of rats for HE determination of femoral head necrosis.The expressions of matrix metalloproteinase-1 (MMP-1 ), matrix metalloproteinase-2 (MMP-2 ), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1 ),and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2 )at mRNA and protein levels were detected by RT-PCR and Western blot techniques,respectively.Results The expressions of MMP-1 and MMP-2 at mRNA and protein levels were higher in glucocorticoid group than those in the control group. However,TIMP-1 and TIMP-2 gene and protein expression levels were lower in glucocorticoid group (all P<0.05). Conclusion The expressions of MMPs in bone tissues of rat femoral head in early necrosis were increased,but their inhibitors had decreased expressions. We can draw the conclusion that glucocorticoid-induced necrosis of femoral head may be related to its regulation of the expression levels of MMPs and their related inhibitors.

Fragile X syndrome(FXS)is caused by abnormal duplication and amplification of the FMR1 gene CGG.This article reports a pair of brothers diagnosed with FXS by genetic testing.Two patients,aged 15 and 14 years old respectively,both had clinical manifestations such as language disorders,intellectual disabilities,attention deficit disorder,autism spectrum disorder,and FXS's characteristic facial features.The proband had a rare late-onset epileptic seizure,which was well treated with levetiracetam,while his younger brother had no electroencephalogram abnormalities after repeated follow-up.This pair of cases suggests that the clinical phenotype of FXS has diversity and heterogeneity.