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Numerical simulations of geometrical and electromagnetic effects on the distributions of the magnetic induction, the electric field, the current density, the power loss density, and the hysteretic ac loss of a type-II superconductor strip exposed to an oscillating transverse magnetic field are performed by resorting to the quasistatic approximation of a vector potential approach. The underlying definition of the superconducting constituent makes use of a generalized 'smoothed' Bean model of the critical state, which includes the field dependence of the induced current as well. Based on the Jacobian-free Newton-Krylov approach and the backward Euler scheme, the numerical analysis at hand is tailored to the problem of a variable width/thickness aspect ratio of the superconductor strip. Assigning representative materials characteristics and conditions of the applied magnetic field, the main findings include: (i) at high amplitudes of the applied magnetic field, variations of the magnetic induction, the induced electric field, the induced current density, and the power loss density across the thickness of the strip die away as the latter quantity abates; (ii) at low and moderate amplitudes of the applied magnetic field, the hysteretic ac loss abates rapidly, as the aspect ratio of the strip augments, the field dependence of the induced current merely playing an insignificant part thereby; conversely, whereas the geometrical effect controlled by the aspect ratio of the strip is minute at high amplitudes of the applied magnetic field, a reduction of the hysteretic ac loss occurs due to Kim's extended Ansatz for the critical state. [ABSTRACT FROM AUTHOR]

The stable levitation above permanent magnet is an important characteristic of the bulk high- Tc superconductor (HTS). When an external force pushes the bulk HTS up, down or sideways, or tries to tilt it, a restoring force can return it to its initial position. The HTS Maglev relied on this characteristic can overcome the external force from wind or pass the curve lines successfully. The change of guidance force (GF) during many times lateral movement is studied. Experiments show that GF increases during the lateral movement, no matter what kind of PMG or HTS is used, and the change of the GF slows down after 5 times lateral movement. The pre-load method can reduce the levitation force decay during lateral movement. So the influence of GF by the pre-load method is needed to be studied. It is found that the pre-load method can increase GF and reduce the change of the GF during lateral movement. The Halbach permanent magnetic guideway (PMG) can offer much more GF but the change is larger just as the levitation force decays. The GF of cylindrical bulk HTS increases more than of the rectangular bulk HTS in the pre-load case. The characteristics of the GF during the lateral movement are explained. These results are important for further HTS Maglev vehicle system designs. [ABSTRACT FROM AUTHOR]

Intravenous leiomyomatosis is a rare type of tumor that is histologically benign but biologically invasive. It originates from the smooth muscle of the uterine or the uterine vein. It can grow through the uterus and extend into the pelvic cavity, or grow along the veins without invading the wall of the venous vessel itself. The tumors are estrogen-dependent and can metastasize through the bloodstream. Thus, in addition to continuous growth, some tumors exhibit isolated growths in the venous system and heart chambers or show disseminated growth in the lungs, although distant metastasis to other regions usually do not occur. Currently, there is limited research on this disease, the majority of which are case reports, surgical experience summaries, and differentiation from ordinary gynecological myomas in terms of pathogenesis and radiological diagnostic experience. There are two main theories on the origin of the disease: uterine smooth muscle and smooth muscle of the uterine veins. Some studies have verified the role of estrogen, progesterone receptor-related pathways, and angiogenesis in the development of the disease. The clinical symptoms of this disease are varied, depending on the affected area. In the early stages, when the tumor only affects the pelvic cavity, patients show mild symptoms resulting from pelvic organ compression. When it progresses to the inferior vena cava and heart, patients show more complex symptoms resulting from venous return obstruction, cardiac obstruction, and hemodynamics appearing. Different institutions have proposed different disease staging and classification strategies for different clinical purposes. Some are based on the affected area of the lesion; others are based on the size of the tumor. Although surgery remains the main treatment for this disease, the specific surgical approach, adjuvant drug therapy, and prognosis still need further exploration.

Objective: To investigate the effect and mechanism of hydroxyfasudi (HF), a specific Rho kinase inhibitor, on lipopolysaccharide(LPS)induced endothelial dysfunction. Methods: A total of 24 male Sprague Dawley rats were randomly divided into control group( n =6), HF group( n =6), LPS group( n =6) and LPS + HF group( n =6) with random number table method. There was no special treatment in control group. HF (30 mg/kg) was injected intraperitoneally in HF group. LPS (1 mg/kg) were injected intravenously in LPS group. In LPS+ HF group, HF (30 mg/kg) was injected intraperitoneally, followed by intravenous LPS injection (1 mg/kg) 30 minutes later. All rats were sacrificed after 8 hours, and aortic tissue was extracted. RT-PCR was performed to detect mRNA levels of Rho-associated coiled-coil protein kinase (ROCK)1, connexin (Cx)43 and caveolin (Cav)1. The protein levers of ROCK1, Cx43 and Cav-1 were assessed by Western blot and immunohistochemical staining respectively. Results: (1) RT-PCR experiments showed that mRNA levels of ROCK1(2.67±0.03 vs. 1.00±0.04), Cx43(1.73±0.03 vs. 1.00±0.08), and Cav1(1.85±0.04 vs. 1.0±0.03) in LPS group were significantly higher than in control group(all P <0.05). mRNA levels of ROCK1(0.38±0.02), Cx43(0.58±0.02), and Cav1(0.27±0.01) in LPS + HF group were significantly lower than in LPS group(all P <0.05). (2)Western blot analysis showed that protein levels of ROCK1(3.46±0.82 vs. 2.19±0.56), Cx43(0.33±0.09 vs.0.11±0.06), and Cav1(3.45±0.74 vs. 2.25±0.91) in LPS group were significantly higher than in control group(all P <0.05). Protein levels of ROCK1(1.09±0.52), Cx43(0.01±0.06), and Cav1(2.06±0.40) in LPS + HF group were significantly lower than in LPS group(all P <0.05). (3) Immunohistochemical staining showed that protein levels of ROCK1(84.1±0.953.7±2.9), Cx43(99.1±2.1 vs. 46.2±0.8), and Cav1(167.0±6.4 vs. 84.9±1.0) in LPS group were significantly higher than in control group(all P <0.05). Protein levels of ROCK1(30.4±0.6), Cx43(21.4±1.3), and Cav1(55.8±2.8) in LPS + HF group were significantly lower than in LPS group(all P <0.05). Conclusion: HF attenuates LPS induced endothelial dysfunction probably via suppressing the expression of ROCK1, Cx43 and Cav1.

Nodal has been thought to be an embryo-specific factor that regulates development, but nodal is also expressed in the mouse placenta beginning at midgestation, specifically in the spongiotrophoblasts. In an insertional null nodal mutant, not only is embryonic development disrupted, but mouse placental development is also grossly altered with the loss of the diploid spongiotrophoblasts and labyrinth and an expansion of the polyploid giant cell layer. A hypomorphic mutation in nodal results in an expansion of the giant cell and spongiotrophoblast layers, and a decrease in labyrinthine development. Expression of nodal in trophoblast cell cultures is sufficient to inhibit trophoblast giant cell differentiation, demonstrating that nodal can act directly on trophoblasts. The mechanism of nodal action includes the inhibition of junB gene transcription. These results suggest that nodal may be involved in redirecting trophoblast fate towards the midgestational expansion of the labyrinth region while maintaining the thin layer of trophoblast giant cells and the underlying layer of spongiotrophoblasts that form the boundary between the maternal and extraembryonic compartments., (Copyright 2001 Academic Press.)

An analysis of the pattern of expression of the mouse placental hormone prolactin-like protein A (PLP-A) has revealed that this hormone is expressed exclusively in secondary trophoblast giant cells but not in primary giant cells. Thus, PLP-A serves as a marker for a subset of giant cells. Recent results have indicated that PLP-A binds to and inhibits the activity of natural killer cells, and thus, the localized expression of PLP-A may be important for regulating the activity of this class of T lymphocytes in a restricted region of the implantation site. Previous studies indicated that the transcription factor GATA-2 is required for the trophoblast giant cell-specific expression of two other hormones in the prolactin family, placental lactogen I and proliferin. In the absence of GATA-2, PLP-A continues to be expressed, but in this mutant background, PLP-A mRNA is detected in both primary and secondary giant cells. Thus, GATA-2 contributes both to positive and negative regulation of trophoblast giant cell-specific gene expression, and this factor apparently plays an important role in generating or maintaining the distinct functions of secondary, compared with primary, trophoblast giant cells.

Heterodimeric quaternary structures for two enzyme complexes from Lactobacillus acidophilus R-26 exhibiting deoxycytidine kinase/deoxyadenosine kinase (I) and deoxyguanosine kinase/deoxyadenosine kinase(II) activities have been proven by the following steps: (1) separation of each complex into two components on SDS-PAGE at pH 6.6; (2) N-terminal amino acid sequencing of each component; (3) functional assignment of each component by differential limited proteolysis. The third step was facilitated by the finding that the binding of a specific end-product inhibitor dNTP, to each kinase active site makes the corresponding kinase subunit resistant to trypsin, while leaving the heterologous kinase subunit susceptible to proteolysis. Analysis on SDS-PAGE has revealed only two fragments (15.8 and 11.0 kDa) following proteolysis of dCyd kinase/dAdo kinase (I) with trypsin in the presence of dATP. This may indicate that the kinase polypeptide chain (27.2 kDa) not protected by dNTP is cut by trypsin at a single specific site, with concomitant loss of activity. Thus, this work presents a unique approach to the clarification of structure and function of enzymes composed of heterologous subunits.