Objective To study the closure time of neonatal ductus venosus and the Z score regression equation, and to explore the variation of closure time of neonatal ductus venosus with gestationalage.Methods Color doppler ultrasound was applied to detect the closure time of neonatal ductus venosus in normal newborns, Z score regression equation ( lnY =a +bX +cX2 ) for the closure time of neonatal ductus venosus ( Y ) was developed by regression analysis which used gestational age ( X) as an independent variable. The Z scores of the closure time of neonatal ductus venosus in different gestational age were calculated by the formula [ Z = ( M - Y )/S x , M for observation value, Y for predictivevalue].Results There were 432 cases in our study.The closure time of neonatal ductus venosus was negatively related to gestational age ( r = -0. 938 , P <0. 001 ) . The nonlinear regression equation was lnY= -5. 228+0. 089X-0. 000228X2, R2 =0. 854, Sx =0. 214(P<0. 001). Based on the predicted mean of the closure time and Sx related to different gestational age, Z scores for specific closure time of neonatal ductus venosus could be calculated by the formula [ Z =( M -Y)/Sx ] . The Z scores were normally distributed,and did not change with gestational age.Conclusions Theclosure & nbsp;time of neonatal ductus venosus is negatively related to gestational age. The Z scores obtained by the predicted nonlinear regression equation are normally distributed.

Objective In order to study the biological characteristics of macrophages and provide the materials to study the survival mechanism of intracellular parasites, we conducted this study to establish a high-purity alveolar macrophage isolation and culture method.Methods Goat lungs were lavaged with normal saline in sterile environment several times, and cells were collected and then goat alveolar macrophages were purified by density gradient centrifugation using peripheral blood mononuclear cells (PBMC) solution.The isolated goat alveolar macrophages were cultured in cell culture medium containing 10% fetal bovine serum and cell morphology was observed under an inverted microscope every day,and the phagocytic activity of the cells was detected by chicken red blood cell phagocytosis test.Flow cytometry was used to detect CD14, a characteristic monocyte-macrophage surface marker.Results The adherent cells were characterized by typical macrophage morphology, pseudopodia and protrusions, showing round and irregular shape, rich cytoplasm, and large cell body.Of the cultured macrophages, 54.5% could phagocytize chicken erythrocytes and showed good phagocytic activity.After one month of in vitro culture, 93.7% of the cells were able to express CD14 antigen, which had a macrophage-specific immunophenotype.Conclusions The alveolar macrophages obtained in this study have high purity and good bioactivity, thus provide a cell model for studying the immune mechanism of intracellular parasites.