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排序方式: 共有970条查询结果,搜索用时 29 毫秒
91.
92.
This paper describes an interactive system for specifying robotic tasks using virtual tools that allow an operator to reach into a live video scene and direct robots to use corresponding real tools in complex scenarios that involve integrating a variety of otherwise autonomous technologies. The attribute rich virtual tools concept provides a human-machine interface that is robust to unanticipated developments and tunable to the specific requirements of a particular task. This Interactive Specification concept is applied to intermediate manufacturing tasks. 相似文献
93.
FJ Garcia-Criado N Eleno F Santos-Benito JJ Valdunciel M Reverte FS Lozano-Sánchez MD Lude?a A Gomez-Alonso JM López-Novoa 《Canadian Metallurgical Quarterly》1998,66(8):982-990
BACKGROUND: Tissue subjected to a period of ischemia undergoes morphological and functional damage that increases during the reperfusion phase. The aim of the present work was to assess the possible improvement induced by exogenous administration of nitric oxide (NO) on renal injury and inflammatory reaction in an experimental animal model of renal ischemia-reperfusion (I-R). METHODS: Ischemia was achieved by ligation of the left arteria and vein for 60 min, followed first by contralateral nephrectomy and then reestablishment of blood flow. Molsidomine, used as an NO donor, was administered by systemic injection 30 min before reperfusion. The effect of molsidomine was compared with the effect of hydralazine, a non-NO donor hypotensive agent. RESULTS: Treatment with molsidomine improved the renal dysfunction (increase in plasma creatinine and urea levels) caused by I-R. Moreover, molsidomine blunted the enhanced production of proinflammatory cytokines (tumor necrosis factor [TNF]-alpha and interleukin [IL] 1alpha), the increase in tissular levels of superoxide anions and oxygen free radical scavengers, and the neutrophilic infiltration observed in the ischemic kidney. One hundred percent survival was achieved in the group of animals treated with the NO donor, whereas the groups of animals undergoing I-R that did not receive molsidomine showed a 40% mortality from the second day after reperfusion. CONCLUSIONS: The present work demonstrated that systemic treatment with an NO donor before reperfusion improved renal function and diminished inflammatory responses in a kidney subjected to an I-R process. 相似文献
94.
BS Atiyeh AM Hamdan SI Nassar FS Hanbali HA Hashim 《Canadian Metallurgical Quarterly》1996,37(4):422-427
The capabilities of current protein structure prediction methods have been assessed from the outcome of a set of blind tests. In comparative modeling, many of the numerical methods did not perform as well as expected, although the resulting structures are still of great practical use. The new methods of fold identification ('threading') were partially successful, and show considerable promise for the future. Except for secondary structure data, results from traditional ab initio methods were poor. A second blind prediction experiment is underway, and progress in all areas is expected. 相似文献
95.
D Donnini AM Zambito G Perrella FS Ambesi-Impiombato F Curcio 《Canadian Metallurgical Quarterly》1996,219(2):412-417
It has been reported that glucose may autooxidize generating free radicals which have been hypothesized to induce important cellular abnormalities. To investigate the cell damage induced by glucose-dependent oxidative stress, the FRTL5 cell strain was incubated in 10 or 20 mM glucose, either alone or in the presence of buthionine-sulfoximine, a transition state inhibitor that blocks glutathione synthesis. We found indeed that buthionine-sulfoximine greatly inhibited glutathione production and increased malondialdehyde (a marker of oxidative cell damage) levels, especially in 20mM glucose. We also found that, when glutathione production was inhibited, 10mM glucose induced apoptosis and 20 mM glucose induced necrosis. These data show that the glucose-dependent cell damage is a function of glutathione production. They also show that such glucose-dependent free radical production may be critical for determining cell damage, even for small variations as the ones we tested (from 10 to 20 mM glucose). 相似文献
96.
Chronic glucocorticoid therapy causes rapid bone loss and clinical osteoporosis. We found that although the glucocorticoid, dexamethasone, stimulated osteoblast maturation, it also inhibited proliferation of a preosteoblastic cell line, MBA-15.4. The dexamethasone-induced decline in preosteoblast proliferation correlated with a 30-40% reduction in protein kinase C/TPA-stimulated mitogen-activated protein kinase (MAPK) activity. These steroid effects only became evident after 6-24 h treatment, implying that dexamethasone acts on de novo synthesis of proteins. Because MAPK is inactivated by dephosphorylation of tyrosine and threonine residues, cells were treated concomitantly for 24 h with dexamethasone and inhibitors of tyrosine (sodium orthovanadate) and/or serine/threonine phosphatases (sodium fluoride). MAPK activity and cell proliferation were restored when MBA-15.4 cells were treated with vanadate, suggesting that dexamethasone up-regulates tyrosine phosphatase activity. Inactivation of serine/threonine phosphatases with sodium fluoride had no effect. Inhibition of the PKA pathway (which is growth inhibitory in mature osteoblasts) with H-89 did not reverse the effects of dexamethasone. Pretreatment with dexamethasone inhibited both peak- and extended activation plateau-phases of MAPK activity. Both phases were fully restored by pretreatment with vanadate, implicating more than one tyrosine phosphatase. Cycloheximide, alone or in combination with dexamethasone, prevented drop-off from plateau to basal levels, suggesting that an inducible dual-specificity phosphatase regulates the plateau-phase. We conclude that dexamethasone may inhibit preosteoblast growth via a novel tyrosine phosphatase pathway. 相似文献
97.
98.
We have demonstrated the presence of epidermal growth factor (EGF) and its receptors in human non-gestational corpora lutea. To determine further the characteristics of EGF receptor binding, we examined 30 human corpora lutea throughout the luteal phase and during pregnancy. Scatchard plots of EGF binding in 29 of the 30 corpora lutea were curvilinear, suggesting negative co-operativity. The mean +/- SE of the association constant Ka was (0.9 +/- 0.2) x 10(9) l/mol, the dissociation constant Kd was (2.2 +/- 0.3) x 10(-9) mol/l and the number of binding sites (Rt) was (15.8 +/- 2.1) x 10(-19) mol/micrograms protein for non-gestational corpora lutea. The Kd increased significantly in late pregnancies compared to early pregnancies (P = < 0.005), while Rt was significantly higher in term pregnancies than in either early pregnancy (P < 0.01) or the menstrual cycle (P < 0.001). Corpora lutea atretica (n = 2) and ovarian stroma (n = 6) did not show any EGF binding activity. Our findings demonstrate the presence of specific EGF receptors in human corpora lutea of both the menstrual cycle and pregnancy. The changes in EGF binding parameters in early pregnancy suggest that there may be a relationship between the role of EGF and ovarian steroidogenesis. 相似文献
99.
100.
OBJECTIVE: To investigate the role of tumor persistence in patients submitted to irradiation therapy and radical hysterectomy. DESIGN: A retrospective analysis of prognostic factors. LOCATION: Hospital A.C. Camargo, S?o Paulo, Brazil, a private non-profitmaking foundation and tertiary referral centre. PATIENTS: A total of 629 cases of invasive squamous cell carcinoma of the cervix were studied. Criteria for inclusion in the study were: confirmed histological diagnosis of squamous cell carcinoma and no previous treatment (except for preoperative radiotherapy carried out at the Hospital A.C. Camargo itself). At the end of the follow-up period, 410 patients (65%) had no evidence of disease and 219 (34.8%) had died because of the tumor. INTERVENTION: The patients were submitted to radical surgery and radiation therapy, separately or in combination between 1953 and 1982. MAIN OUTCOMES MEASURES: Multivariate analysis of the different variables was performed according to the Cox regression method. RESULTS: The variables of prognostic value were, in decreasing order of importance: the decade of patient admission (p = 0.0001), the modality of therapy employed (p = 0.0005), the presence of residual tumor in the surgical specimens (p = 0.0055) and the clinical stage of the disease (p = 0.0575). CONCLUSION: Radiation therapy controlled a considerable number of local tumors and pelvic lymph nodes but not all of them in every patient. There is a specific group of patients for whom radical surgery is necessary to achieve control of the disease. 相似文献