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Superoxide dismutases in the human colorectal cancer sequence (1999)

Janssen, A. M. L. ; Bosman, C. B. ; Kruidenier, L. ; [et al.]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 327-335

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ISSN: 1432-1335

Keywords: Key words Adenomas ; Colorectal cancer ; Liver metastases ; Superoxide dismutases

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Purpose : The oxidant-antioxidant balance within tissues is thought to contribute to the development and progression of cancer. Previous investigations have indicated changes in this balance during the colorectal oncogenic process that merit further investigation. The aim of the present study was to evaluate whether the human colorectal cancer sequence is accompanied by changes in the protein and activity levels of the antioxidant enzymes manganese- and copper/zinc-superoxide dismutase (Mn-SOD and Cu/Zn-SOD). Patients and methods : SOD levels were assessed in colorectal adenomas, carcinomas, and liver metastases and were compared with those in the corresponding normal tissues (n=35 in each group). Mn- and Cu/Zn-SOD expression was first evaluated semiquantitatively by electrophoretic activity analysis, immunoblotting, and immunohistochemistry and was subsequently quantified by enzyme-linked immunosorbent assays (ELISAs) and spectrophotometric activity assays. Results : The semiquantitative analyses showed enhanced Mn-SOD levels, primarily localized in (neoplastic) epithelial cells, in carcinomas, and in liver metastases as compared with adenomas and normal mucosa, whereas no consistent pattern was observed for Cu/Zn-SOD. Normal liver tissue expressed the highest levels of both SODs. The quantitative SOD analyses confirmed these observations and revealed that carcinomas and liver metastases expressed 2–4 times more Mn-SOD protein and enzymatic activity (0.0005 〈 P ≤ 0.01) than did the normal mucosa. Adenomas expressed intermediate Mn-SOD levels, which increased significantly with the diameter and tended to increase with the grade of dysplasia and presence of a villous component. In contrast, adenomas, carcinomas, and the corresponding normal mucosa were found to have a similar Cu/Zn-SOD content, whereas liver metastases contained significantly (P 〈 0.02) more Cu/Zn-SOD as compared with these tissues. In addition, the Cu/Zn-SOD content was not related to any histopathological characteristic of the carcinomas or adenomas. Conclusions : Our study indicates that the development of neoplasia in the human colorectum is accompanied by major changes in the level and activity of Mn-SOD. This observation illustrates that Mn-SOD might have a functional role in human colorectal carcinogenesis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004320050282

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General considerations of numerical stability and accuracy in inviscid, compressible flow calculations employing primitive variables (1982)

Bosman, C. ; Ahrabian, D. ; Kahrom, M.

Chichester : Wiley-Blackwell

International Journal for Numerical Methods in Fluids 2 (1982), S. 123-149

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ISSN: 0271-2091

Keywords: Three-dimensional ; Flow ; Computation ; Scheme ; Time ; Marching ; Conventional ; Damping ; Old Time Level ; Current Time Level ; Fourier Perturbation ; Staggered Grid ; Engineering ; Engineering General

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: The numerical stability of a number of computation schemes currently used for three-dimensional, inviscid, compressible flow is analysed using one-dimensional Fourier analysis. Whereas Reference 1 analysed schemes which were modified to render them amenable to simple analysis, the present work analyses the stability of schemes as actually used by Highton,3 Ahrabian,1 Denton2 and Spalding.6 The use of current values of the variables as they become available is shown to bring a general improvement to stability margin. The manner of damping introduced by the time marching formulation is shown to be deleterious to modifications which reduce truncation error. Staggered grid schemes can be formulated to second order accuracy with better stability margin than the corresponding first order scheme. While unstaggered grid schemes can be formulated to second order error and remain stable, their stability margin becomes very small. Agreement of the theory with numerical experiments continues to be of a high order for both one and three-dimensional disturbances.

Additional Material: 12 Ill.