RESUMO
Objective To evaluate the effect of PTH gene polymorphisms on bone mineral density (BMD) at multiple skeletal sites in normal females.Methods PTH gene phenotype was determined by PCR-RFLP of restriction enzyme Bst BⅠin 596 females aged (46.3?13.7) years (20-80 years),and PCR products with or without enzymolytic site were considered as genotype B or genotype b respectively.BMDs of the anteropesterior spine (AP) and supine lateral spine (Lat) of lumbar vertebrae (L_1-L_4),femoral neck (FN),total hip (T-hip), Ward's triangle (Ward),Trochanter (Troch),forearm [radius+ulna ultradistal (RUUD) and total area of radius + ulna (RUT) ] were measured by DEXA (QDR4500A).Results (1) Hardy-Weinberg equilibrium was evident for PTH polymorphisms.The frequencies of genotype were BB 0.784,Bb 0.208,bb 0.008 and frequencies of alleles B,b were 0.888 and 0.112 respectively in 596 normal females.Frequencies of BB,Bb,bb genotypes were 0.781,0.210,and 0.009 respectively in 347 postmenopausal women and their frequencies of alleles B,b were 0.886,0.114.No significant difference was found between post- and premenopausal women in genotype frequen- cy.(2) Comparing their BMDs of AP,Lat,FN,T-hip,Ward,Troch,RUUD and RUT,there was no significant difference between BB and Bb genotypes of pre- and postmenopansal women groups.(3) Logistic regression analysis failed to show any statistical difference between normal and osteoporosis women with regard to PTH phenotype.Conclusion PTH gene polymorphism has little effect on BMD in normal females.
RESUMO
Objective To observe apelin and its receptor (APJ) expressions in human osteoblasts and evaluate the effect of apelin on osteoblasts.Methods The expressions of apelin and APJ in human osteoblasts were tested by RT-PCR and Western blot.After human osteoblasts were treated with apelin,cell proliferation was measured by [~3H] thymidine incorporation and cell counting.Cell function was measured by alkaline phosphatase (ALP) activity,the secreted osteocalcin level and typeⅠcollagen production .The activation of signaling cascades was tested by Western blot.Small-interfering RNA (siRNA) to blockade APJ was applied to observe effects of apelin on cell proliferation and the activation of signaling cascades.Results Both apelin and APJ were expressed in human osteoblasts.Apelin increased the proliferation and did not show the influences on ALP activity, osteocalcin secretion and type I collagen production in human osteoblasts.Apelin induced activation of phosphatidylinositol-3 kinase (PI3K) downstream effector (Akt),but not mitogen-activated protein kinase (MAPK) such as c-jun N-terminal kinase (JNK),p38 and ERK1/2 in human osteoblasts.Suppression of APJ with siRNA or LY294002 (PI3K inhibitor) abolished the apelin-induced cell proliferation and the activation of Akt.Conclusion Human osteoblasts express apelin and APJ.Apelin stimulates the proliferation of human osteoblast via APJ/PI3K/Akt pathway,but has no effect on osteoblast differentiation.