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31.
Pleiotrophin (PTN) is a heparin-binding cytokine that functions as a neurite outgrowth promoting and mitogenic activity in vitro. PTN is highly conserved and its gene is widely expressed in mammalian tissues during development, suggesting important roles of PTN in vivo. However, the mechanisms by which PTN mediates its functional activities are unknown. We now report that an approximately 200 kDa (p200) protein is phosphorylated (pp200) in PTN stimulated NIH 3T3 and NB41A3 cells five minutes after stimulation with PTN. Phosphorylation is maximum at 15 minutes and is PTN concentration dependent. pp200 is recognized by antiphosphotyrosine antibodies and contains both phosphotyrosine and phosphoserine by phosphoamino acid analysis. The results suggest that PTN functions in part through activation of protein kinase(s) in NIH 3T3 and NB41A3 cells. 相似文献
32.
In multiple pregnancies, survival of remaining fetuses after premature death and delivery of one fetus is uncommon. We report a case of a triplet pregnancy that was reduced to twins at the 14th gestational week and then had preterm premature rupture of membranes and intrauterine fetal death of one twin at the 17th gestational week. To save the surviving fetus, delivery of the dead fetus and ligation of the umbilical cord at the cervical level were performed. We also performed McDonald cervical cerclage to keep the placenta of the dead fetus as well as that of the surviving one in the uterine cavity. After a series of aggressive procedures, including immediate administration of tocolytic agents, and antibiotic prophylaxis to prevent infection and preterm labor, the surviving fetus was delivered vaginally 73 days later due to intractable uterine contractions. After a 10-week hospital stay, the infant boy, weighing 2,500 g, was discharged without any sequelae. To our knowledge, this was the longest interval between deliveries in a triplet pregnancy reported in Taiwan. With adequate intensive management, a satisfactory outcome of the fetus and mother in such cases is possible. 相似文献
33.
34.
Kim S. Jeong S. Lee Y.T. Kim D.-H. Lim J.-S. Seo K.-S. Nam S. 《Electronics letters》2002,38(13):622-623
A new ultra-wideband, low-loss and small-size coplanar waveguide (CPW) to coplanar strip (CPS) transition which can be used from DC to 110 GHz is presented. The proposed transition connects CPW with CPS by the reformed air-bridge. Two ground planes of CPW are tied at their ends by a line and the centre of the line is connected to the ground strip of CPS by another line. Owing to the symmetry of the proposed structure, the currents of two ground planes of CPW are combined with the same phase and transferred to the ground strip of CPS. With height of 3 μm, the signal line of CPW passes over two connecting lines and is connected to the signal strip of CPS. For the back-to-back transition structure, insertion loss <1 dB and return loss >15 dB are obtained from 0.5 to 110 GHz 相似文献
35.
A chimeric dopamine transporter (DAT) cDNA encoding mutant human DAT (hDAT) protein in which the intracellular carboxyl-terminal tail is replaced by that of the bovine dopamine transporter (bDAT) was constructed. The chimeric hDAT cDNA was expressed in COS-7 cells, and [3H]dopamine and [3H]MPP+ uptake and [3H]CFT binding capacities were assessed. Substrate transport and ligand binding of bDAT were reduced by 32-43% as a result of substitution of the carboxyl tail in hDAT, suggesting that the functional characteristics of bDAT arise from differences in the carboxyl tail between human and bovine DAT. Thus, it appears that the sequences encoded within the carboxyl terminal of DAT would be one of the important determinants for its functions. 相似文献
36.
The purpose of this study was to evaluate the relationship between the number of yolk sacs and amnionicity in monochorionic twin pregnancies scanned early in the first trimester. We retrospectively reviewed images of all monochorionic twins scanned between 6 and 9.5 weeks' gestation and with pathologic or sonographic confirmation of chorionicity-amnionicity. Each film was reviewed for the number of yolk sacs present, as well as for the gestational age at which the amniotic membrane was first visualized. Twenty monochorionic-diamniotic pregnancies and two monochorionic-monoamniotic pregnancies met the criteria for inclusion in the study. In diamniotic pregnancies scanned at less than 8 weeks' gestation, only the yolk sacs were identified; none of the dividing amniotic membranes were detected. Two yolk sacs were identified in all but one case. In this case, although one yolk sac was seen at 6 weeks, follow-up scanning at 8 weeks revealed two yolk sacs. In each of the monochorionic-monoamniotic twin pregnancies, one yolk sac was seen at 9 weeks and a single amnion encircled both embryos. We conclude that the sonographic identification of two yolk scas in monochorionic twins enables us to make the diagnosis of diamniotic twins early in the first trimester, before the amniotic membrane can be imaged. The presence of one yolk sac should prompt a follow-up ultrasonogram to assign amnionicity definitively. 相似文献
37.
Young Nam Chun Jen-Shih Chang Alexander A. Berezin J. Mizeraczyk 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(1):119-124
Numerical modelling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. Solutions of the steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The CFD code coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force, was used for the numerical simulation with the Chen-Kim k-epsiv turbulent model. The numerical results show that EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode (Re cw=12.4). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases 相似文献
38.
39.
Degradation of analog device parameters such as drain conductance, gd, due to hot carrier injection has been modeled for NMOSFET's. In this modeling, mobility reduction caused by interface state generation by hot carrier injection and the gradual channel approximation were employed. It has been found that gd degradation can be calculated from linear region transconductance, gm, degradation which is usually monitored for hot carrier degradation of MOSFET's. The values of gd degradation calculated from gm degradation fit well to the measured values of gd degradation The dependence of the gd degradation lifetime on Leff has been also studied, this model also provides an explanation of the dependence on Leff. The model is then useful for lifetime predictions of analog circuits in which gd degradation is usually more important than gm degradation 相似文献
40.
Spectrally stable Er-fiber laser for application in phase-sensitive optical time-domain reflectometry 总被引:3,自引:0,他引:3
Kyoo Nam Choi H.F. Taylor 《Photonics Technology Letters, IEEE》2003,15(3):386-388
A high degree of frequency stability in an Er-fiber laser with the Fabry-Perot configuration was achieved using a long (25-km) optical-feedback loop. The frequency-drift rate was determined to be <1 MHz/min by observing temporal fringes in an unbalanced Mach-Zehnder interferometer. Instantaneous linewidth measured with a delayed self-heterodyne interferometer was less than the 3-kHz resolution limit. The laser was utilized in an optical time-domain reflectometry experiment to detect and locate a time-varying phase perturbation applied to an optical fiber. 相似文献