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- Verbaan, Hans, et al.
(författare)
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Hepatitis C in chronic liver disease: an epidemiological study based on 566 consecutive patients undergoing liver biopsy during a 10-year period
- 1992
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Ingår i: Journal of Internal Medicine. - 1365-2796. ; 232:1, s. 33-42
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Tidskriftsartikel (refereegranskat)abstract
- We analysed the presence of hepatitis C virus (HCV) antibodies in 566 patients undergoing liver biopsy. While over 20% of the patients were anti-HCV positive according to ELISA, only 13.8% had HCV antibodies when tested with a four-antigen recombinant immunoblot assay (RIBA 2). At the time of inclusion in the study, most patients were asymptomatic, irrespective of whether they were HCV-positive. Histological findings in anti-HCV-positive patients were chronic persistent hepatitis, chronic active hepatitis or cirrhosis in greater than 75% of cases. Only four of the patients who were anti-HCV-positive according to the RIBA 2 had autoimmune chronic active hepatitis. Risk behaviour could be identified in the majority of cases. Community-acquired sporadic cases were rare (12%). Of the 153 patients who died during follow-up, 23 subjects were anti-HCV positive. Although age- and sex-adjusted survival was not shorter in anti-HCV-positive patients than in anti-HCV-negatives, the risk of hepatocellular cancer was higher (P = 0.01). We conclude that HCV infection is associated with chronic liver disease, even when critical evidence of viral aetiology is slight. Truly sporadic cases are rare. Patients infected with HCV are at increased risk of developing hepatocellular cancer.
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| 2. |
- Eriksson, Arne S., 1961
(författare)
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Elastic Wave Scattering by Closed Cracks and Thin Flaws - Multiple Scattering and Resonances
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis we study elastic wave scattering by thin flaws and closed cracks, which finds applications in ultrasonic testing and evaluation of materials. First we consider the scattering of an SH-wave by a thin finite elastic layer between two elastic half-spaces. The layer, thin compared to the wavelengths involved, is modelled by spring boundary conditions extended with terms accounting for inertia forces. A direct integral equation method is used, with the discontinuity of displacement and traction over the thin layer as the unknowns. Numerical results are given for the scattered energy and the far field amplitude. We also investigate the elastodynamic scattering by two penny-shaped cracks with spring boundary conditions in the fully three-dimensional case. The transition matrix of a single crack is first determined by a direct integral equation method which gives the crack-opening displacement (COD) and the integral representation which subsequently gives the scattered field expanded in spherical waves. Two cracks are considered by a multi-centered T matrix approach where the matrix inverses are expanded in Neumann series. Rotation matrices are employed so that the cracks may have an arbitrary orientation. The numerical procedures are very stable and it has been possible to go to quite high frequencies. The back-scattered longitudinal far field amplitude is computed both in the frequency and time domain in a few cases and the effects due to multiple scattering are in particular explored. The natural frequencies of one partially closed penny-shaped crack are calculated for the symmetric part of the problem. The natural frequencies are given as the complex SEM (singularity expansion method) poles of the symmetric part of the T matrix. A clear correlation is shown between the migration of the poles, as the crack gets more closed, and the frequencies at which the scattering cross section has its peaks.
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