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71.
If the previous restorative therapy or dental caries has resulted in substantial loss of tooth structure, the abutment teeth for fixed prosthodontic restorations require a core reconstruction or a post and core. Small dentin defects can be restored with bonded cores; more extensive dentin defects that are often accompanied by previous endodontic treatment generally require additional support for the core material. A direct procedure with a bonded post is a viable treatment method. The decision to use either light-conducting all-ceramic zirconium or titanium as a post material depends on the aesthetic requirements present. The indications for a cast post and core as an indirect procedure for prosthodontic reconstructions appear to be decreasing. The learning objective of this article is to review the past and current post and core materials and techniques. Indications for core reconstruction with vital teeth and posts and cores for pulpless teeth are discussed. 相似文献
72.
Insulin-like growth factor I activates the invasion suppressor function of E-cadherin in MCF-7 human mammary carcinoma cells in vitro 总被引:1,自引:0,他引:1
ME Bracke BM Vyncke EA Bruyneel SJ Vermeulen GK De Bruyne NA Van Larebeke K Vleminckx FM Van Roy MM Mareel 《Canadian Metallurgical Quarterly》1993,68(2):282-289
The calcium-dependent cell-cell adhesion molecule E-cadherin has been shown to counteract invasion of epithelial neoplastic cells. Using three monoclonal antibodies, we have demonstrated the presence of E-cadherin at the surface of human MCF-7/6 mammary carcinoma cells by indirect immunofluorescence coupled to flow cytometry and by immunocytochemistry. Nevertheless, MCF-7/6 cells failed to aggregate in a medium containing 1.25 mM CaCl2, and they were invasive after confrontation with embryonic chick heart fragments in organ culture. Treatment of MCF-7/6 cells with 0.5 microgram ml-1 insulin-like growth factor I (IGF-I) led to homotypic aggregation within 5 to 10 min and inhibited invasion in vitro during at least 8 days. The effect of IGF-I on cellular aggregation was insensitive to cycloheximide. However, monoclonal antibodies that interfered with the function of either the IGF-I receptor (alpha IR3) or E-cadherin (HECD-1, MB2) blocked the effect of IGF-I on aggregation. The effects of IGF-I on aggregation and on invasion could be mimicked by 1 microgram ml-1 insulin, but not by 0.5 microgram ml-1 IGF-II. The insulin effects were presumably not mediated by the IGF-I receptor, since they could not be blocked by an antibody against this receptor (alpha IR3). Our results indicate that IGF-I activates the invasion suppressor role of E-cadherin in MCF-7/6 cells. 相似文献
73.
C. E. Price G. W. Henderson 《Fatigue & Fracture of Engineering Materials & Structures》1988,11(6):493-500
Abstract— A comparison was made at room temperature of the fatigue sequence in Monel K 500 (N05500), both between the different states of solution heat treated, aged, and overaged, and with nickel that had been studied previously. The test mode was reversed bending and monitoring was by Nomarski interference contrast microscopy, in conjunction with sequential microhardness measurements. It was found that variations in Monel between the heat treated states were minor in comparison to differences with nickel. In Monel, the fatigue resistance was relatively poor because of ready intergranular, as well as transgranular, cracking. To achieve a significant life, the stress level had to be kept well below the yield strength, low enough to delay the onset of visible slip, for cracking would follow promptly. This meant that, in contrast to nickel, stress levels high enough to invoke strain hardening and obvious secondary slip led to exceedingly short lives. Also, inclusions mattered, slip occurring preferentially in their vicinity. 相似文献
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Male Swiss-Webster mice were rendered tolerant to morphine by subcutaneous implantation of a morphine pellet, each containing 75 mg morphine base, for 3 days. Mice implanted with placebo pellets served as controls. A high degree of tolerance to the analgesic effect of morphine developed as evidenced by decreased analgesic response to various doses of morphine. A selective kappa-opiate agonist, U-50,488H (8, 16 and 32 mg/kg, i.p.) produced dose-dependent analgesic and hypothermic effects in mice implanted with placebo pellets. A significant decrease in the analgesic and hypothermic effects of U-50,488H was observed in morphine tolerant mice as compared to placebo-treated mice. Mice were rendered tolerant to U-50,488H by injecting the drug (25 mg/kg, i.p.) twice daily for 4 days. Vehicle injected mice served as controls. Tolerance to the analgesic and hypothermic effects of U-50,488H in mice injected chronically with the drug was evidenced by the decreases in the intensity of these responses when compared to those observed in vehicle injected controls. Morphine produced a dose-dependent analgesic and hypothermic effects in mice injected chronically with vehicle but the intensity of these effects was significantly lower in mice injected chronically with U-50,488H. These results indicate that a substantial tolerance to analgesic and hypothermic effects of U-50,488H develops in morphine tolerant mice. The effect of chronic injections of U-50,488H on the binding of [3H]ethylketocyclazocine (EKC) and [3H]D-Ala2,MePhe4,Gly-ol5-enkephalin (DAMGO) to whole brain and spinal cord kappa- and mu-opiate receptors was determined.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
78.
Tuberculous meningitis remains an important illness that can be difficult to diagnose in a timely fashion and carries significant morbidity. We present a retrospective review of the cases of tuberculous meningitis diagnosed and treated at a single institution. Fifty-eight cases were identified and stratified according to stage of disease at presentation. Four patients (7%) died; three (5%) developed severe neurological sequelae. Poor outcomes were largely confined to cases presenting in an advanced stage and at the extremes of age. Corticosteroids were administered to 56 patients and may have contributed to the comparatively good outcome in these cases. 相似文献
79.
This work utilizes proteoliposomes reconstituted with renal Na(+)-K(+)-ATPase to study effects of electrical potential (40-80 mV) on activation of pump-mediated fluxes of Na+ or Rb+ (K+) ions and on inhibitory effects of Rb+ ions or organic cations. The latter include guanidinium derivatives that are competitive Na(+)-like antagonists (David, P., Mayan, H., Cohen, H., Tal, D. M., and Karlish, S.J.D. (1992) J. Biol. Chem. 267, 1141-1149). Cytoplasmic side-positive diffusion potentials significantly decreased the K0.5 of Na+ at the cytoplasmic surface for activation of ATP-dependent Na(+)-K+ exchange but did not affect the inhibitory potency of Rb+ (K+) or any Na(+)-like antagonist. Diffusion potentials did not affect activation of Rb(+)-Rb+ exchange by Rb+ ions at the cytoplasmic surface and had only a minor effect on Rb+ activation at the extracellular surface. Previously, we proposed that the cation binding domain consists of two negatively charged sites, to which two K+ or two Na+ ions bind, and one neutral site for the third Na+ (Glynn, I. M., and Karlish, S.J.D. (1990) Annu. Rev. Biochem. 59, 171-205). The present experiments suggest that binding of a Na+ ion in the neutral site at the cytoplasmic surface is sensitive to voltage. By contrast, binding of Rb+ ions at the extracellular surface of renal pumps appears to be only weakly or insignificantly affected by voltage. Inferences on the identity of the charge-carrying steps, based on experiments using proteoliposomes, are discussed in relation to recent evidence that dissociation of Na+ or association of K+ ions, at the extracellular surface, represent the major charge-carrying steps. 相似文献
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