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This article emphasizes the contributions that new diagnostic techniques have made toward the management of children with brain tumors. The development of computerized tomographic (CT) scanning has revolutionized both the diagnosis and management of patients with brain tumors and has obviated the previously inevitable delays in diagnosis. The development of magnetic resonance imaging (MRI) has certainly facilitated diagnosis of brain tumors in certain locations with the brain, but it remains unproven in other locations. It is clear that at least some of the early promise of MRI scanning has not been realized. Neither CT nor MRI are able to provide functional detail within the brain, nor are they able to differentiate tumor from peritumoral edema to better delineate the tumor margins. It is hoped that the currently experimental techniques of Positron Emission Tomography (PET) scanning and contrast-enhanced MRI scanning will provide such information in the near future. Neurophysiologic methods of assessing brain tumors merit greater consideration than has been afforded to date. Sensory evoked-potential monitoring provides information about nervous system function. This information is useful both in diagnosis and in monitoring of brain tumors, since the functional information can be localized to discrete regions within the brain. The value of cerebrospinal fluid (CSF) evaluation, both for cytology and tumor markers, cannot be overstated. A significant proportion of childhood brain tumors tend to seed throughout the neuraxis by the CSF pathways. Thus, evaluation of CSF cytology prior to surgical perturbation of the primary tumor should be undertaken whenever safely feasible, in order to avoid the dilemma of postoperative positive CSF cytology and its questionable significance. 相似文献
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Regulation of intracellular pH in Calu-3 human airway cells 总被引:4,自引:3,他引:1
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R B Bourne H Bitar P R Andreae L M Martin J B Finlay F Marquis 《Canadian journal of surgery》1988,31(1):43-45
Absorbable sutures are initially equal or superior to nonabsorbable sutures in terms of tensile strength but are absorbed at variable rates by the action of hydrolysis. This study demonstrated that the in-vivo half-life tensile strength of the braided absorbable sutures polyglycolic acid (Dexon Plus) and polyglactin 910 (Vicryl) is 2 weeks, whereas those of the monofilament absorbable sutures polyglyconate (Maxon) and polydioxanone (PDS) are 3 and 6 weeks respectively. The addition of a single hitch or six knots reduced the in-vitro tensile strength by 30% to 35%. Polyglyconate (Maxon) suture demonstrated the best in-vitro knot security. 相似文献
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T. K. Moroz J. B. Finlay C. H. Rorabeck R. B. Bourne 《Medical & biological engineering & computing》1988,26(3):271-276
Detailed data of the stability of external fixation devices are needed by the orthopaedic surgeon to predict successful healing
of a fracture. The stability (rigidity, yield and failure criteria) of four half-frame configurations (single, stacked, double
and delta) of the original Hoffmann and AO tubular frame have been analysed under four loading conditions: axial compression,
torsion, and both AP- and ML-bending. Overall the two systems' rigidities were the same between similar configurations. Both
systems' single half-frames were particularly weak; however, as the number of components (rods, pins, clamps, couplings) on
the frame increased, the rigidity of the frame increased. The difference in performance between the two systems lies in their
yield and failure characteristics. The AO system exhibited excellent failure criteria in all modes of loading, i.e. no configuration
failed within the test limits, whereas most Hoffman frames yielded and failed at low loads. 相似文献
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The cytotoxic effects of chemotherapeutic drugs on quiescent and actively proliferating cells of a Lewis lung carcinoma (LLTC) cell line have been examined. The sensitivities of cells in plateau-phase and exponentially growing cultures were compared with those of cells recovered from large subcutaneous tumours both immediately after tumour disaggregation and after one or 4 days in culture. Flow cytometric analysis indicated that when cells freshly prepared from tumours were placed into culture, they underwent extensive recruitment into S-phase. Several drugs were less cytotoxic towards both plateau-phase cultured cells and cells freshly isolated from tumours than they were against exponentially growing cells. These included amsacrine, its 4-methyl-5-(N-methyl)carboxamide derivative CI-921, doxorubicin, and nitrogen mustard. In contrast to these drugs, chlorambucil and plasma from cyclophosphamide-treated mice did not show decreased activity against slowly proliferating cells from cultures or tumours relative to cells in an actively proliferating state. The similar sensitivities of plateau-phase cultured cells and cells taken directly from large growing tumours is direct evidence that plateau-phase cultures are a useful approximation to the state of cytokinetic resistance to chemotherapeutic drugs that prevails in solid tumours, although they may not fully reflect the cytokinetic heterogeneity present in tumours. 相似文献
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