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排序方式: 共有1114条查询结果,搜索用时 15 毫秒
991.
J Fueyo C Gomez-Manzano VK Puduvalli P Martin-Duque R Perez-Soler VA Levin WK Yung AP Kyritsis 《Canadian Metallurgical Quarterly》1998,12(3):665-669
This study evaluated Epstein-Barr virus (EBV) DNA in sera of 42 patients with nasopharyngeal carcinoma (NPC) and 82 healthy individuals who had been infected previously with EBV. Thirteen of 42 NPC samples were positive for EBV DNA in their sera, whereas all 82 normal controls were negative. In addition, EBV typing between primary tumors and sera showed identical results, suggesting that serum EBV DNA represented tumor DNA. To evaluate the importance of the serum NPC DNA, clinical data and tumor phenotypes including age, sex, WHO type, EBV type, stage, tumor invasion, metastasis, and apoptosis were correlated with serum EBV DNA, and only apoptosis was found statistically significant. In conclusion, EBV DNA was detectable in the serum of some patients with NPC, represented tumor DNA, and might have clinical implications in the future. 相似文献
992.
993.
994.
Islet cell antigens have been administered orally and intravenously (I.V.) to NOD mice to assess their abilities to protect from or delay the onset of diabetes, and thereby provide insights that may have therapeutic implications in human trials. Whereas we and others have observed a delay in the onset of diabetes in NOD mice that have been fed with insulin from early life, we report here for the first time that feedings with porcine GAD65 alone (p = 0.226) or in combination with insulin (p = 0.011), have anti-diabetic effects in a prolonged study period (>400 days). While antigen-specific inhibitions of in vitro lymphocytic proliferation responses were seen (p < 0.05), antibody levels were unaffected by oral antigen treatments. IFN-gamma mRNA levels were downregulated in the islet infiltrates following oral antigen treatments while IL-2 and TNF-beta were expressed in all instances. We also observed that I.V. human recombinant GAD65, and porcine GAD given at weaning, delayed diabetes onset (p = 0.004) while similar treatments with a variety of inactive insulin preparations were generally ineffective. These findings thus indicate varying effects of oral and I.V. autoantigen administrations on the development of diabetes in NOD mice, and describe the immunological processes induced by oral autoantigen treatments. 相似文献
995.
996.
PJ Apostolides DG Karahalios RA Yapp VK Sonntag 《Canadian Metallurgical Quarterly》1998,43(2):389-90; discussion 391
The creation of various curves in bendable metallic rods remains difficult. We describe a simple instrument that uses two bending levers to provide the mechanical advantage required to easily shape up to 5.5 mm diameter bendable metallic rods with precision, control, and minimal nicking or scratching of the metal surface. We have successfully used this tool to contour primary and secondary curvatures in threaded Steinmann pins and grooved titanium rods for occipitocervical fusion. 相似文献
997.
VK Ovcharov 《Canadian Metallurgical Quarterly》1994,39(5):3-11
Bireplicon plasmids were constructed. The plasmids consist of DNAs of the streptomycete plasmid pIJ702, the Escherichia coli plasmid pUC19 and the phi C31 actinophage genome fragment encoding the function of the site-specific integration into the chromosome. Part of the plasmids transformed Streptomyces lividans TK64 to thiostreptone resistance. The DNA transforming activity depended on the mutual orientations of the blocks used for the construction and probably depended on the structural stability of the plasmids in S. lividans. The integrative vectors consisting of the pUC19 plasmid DNA and the phage genome fragment with the integrative function efficiently transformed S. lividans. No phage plagues were detected with the standard procedure of integrants' infection by phi C31 phage, despite the absence of the phi C31 phage repressor gene in the integrated DNA. The phi C31 phage mutants including clear and virulent ones were not capable of lytic growth on the integrants. The region determining the limitation of the phi C31 phage lytic development was localized by the deletion analysis of the bireplicon plasmids. As a result actinomycete monoreplicon plasmids were formed. The region is the 1.3 kb phage fragment whose right end maps at 0.2 kb preceding the right end of the phi C31 phage genome linear map. 相似文献
998.
The vnf-encoded apodinitrogenase (apodinitrogenase 2) from Azotobacter vinelandii is an alpha2beta2delta2 hexamer. The delta subunit (the VNFG protein) has been characterized in order to further delineate its function in the nitrogenase 2 enzyme system. Two species of VNFG were observed in cell-free extracts resolved on anoxic native gels; one is composed of VNFG associated with the VNFDK polypeptides, and the other is a homodimer of the VNFG protein. Both species of VNFG are observed in extracts of A. vinelandii strains that accumulate dinitrogenase 2, whereas extracts of strains impaired in the biosynthetic pathway of the iron-vanadium cofactor (FeV-co) that accumulate apodinitrogenase 2 (a catalytically inactive form of dinitrogenase 2 that lacks FeV-co) exhibit only the VNFG dimer on native gels. FeV-co and nucleotide are required for the stable association of VNFG with the VNFDK polypeptides; this stable association can be correlated with the formation of active dinitrogenase 2. The iron-molybdenum cofactor was unable to replace FeV-co in promoting the stable association of VNFG with VNFDK. FeV-co specifically associates with the VNFG dimer in vitro to form a complex of unknown stoichiometry; combination of this VNFG-FeV-co species with apodinitrogenase 2 results in its reconstitution to dinitrogenase 2. The results presented here suggest that VNFG is required for processing apodinitrogenase 2 to functional dinitrogenase 2. 相似文献
999.
BE Miller SR Tosone VK Tam KR Kanter NA Guzzetta JM Bailey JH Levy 《Canadian Metallurgical Quarterly》1998,66(2):535-40; discussion 541
BACKGROUND: Aprotinin consistently reduces blood loss and transfusion requirements in adults during and after cardiac surgical procedures, but its effectiveness in children is debated. We evaluated the hemostatic and economic effects of aprotinin in children undergoing reoperative cardiac procedures with cardiopulmonary bypass. METHODS: Control, low-dose aprotinin, and high-dose aprotinin groups were established with 15 children per group. Platelet counts, fibrinogen levels, and thromboelastographic values at baseline and after protamine sulfate administration, number of blood product transfusions, and 6-hour and 24-hour chest tube drainage were used to evaluate the effects of aprotinin on postbypass coagulopathies. Time needed for skin closure after protamine administration and lengths of stay in the intensive care unit and the hospital were recorded prospectively to determine the economic impact of aprotinin. RESULTS: Coagulation tests performed after protamine administration rarely demonstrated fibrinolysis but did show significant decreases in platelet and fibrinogen levels and function. The thromboelastographic variables indicated a preservation of platelet function by aprotinin. Decreased blood product transfusions, shortened skin closure times, and shortened durations of intensive care unit and hospital stays were found in the aprotinin groups, most significantly in the high-dose group with a subsequent average reduction of nearly $3,000 in patient charges. CONCLUSIONS: In children undergoing reoperative cardiac surgical procedures, aprotinin is effective in attenuating postbypass coagulopathies, decreasing blood product exposure, improving clinical outcome, and reducing patient charges. 相似文献
1000.
The main purpose of the present paper is to give an exact and correct expression describing the properties of the proper length
in arbitrary relativistic translationally moving media in Minkowski space. We show, in particular, that the standard solution
of Bell’s well-known problem [1] must be revised. A new solution has been found, describing the behavior of a finite physical
length in the Lagrangian non-inertial reference frame comoving to the medium. This solution is absent in the existing literature.
We conclude that, in the case of large enough accelerations a
0 and initial distances between some points of the medium, i.e., under the condition u ≡ a
0
L
0/c
2 ≫ 1, where c is the speed of light, the calculations presented in some well-known papers (namely, [1, 2, 10–12]) are incorrect and should
be revised. For the velocity values u ≪ 1, our results and those of all the enumerated papers coincide. 相似文献