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J Riera

Publications and source records attributed to J Riera.

At least 55 records · Page 3Linked to original sources
PubMed1994

Activation of 4-nitro-o-phenylenediamine by the S2 fraction of Zea mays to mutagenic product(s).

Studies on plant metabolic activation with the S2 fraction from Zea mays have been developed. The 4-nitro-o-phenylenediamine (NOP) activation by S2 has been analyzed with the Ames test as a short-term assay. The NOP mutagenic potency was increased two-fold by S2, while rat liver S9 produced the contrary effect. The presence of a NADPH-generating system and the treatment of S2 with CO do not modify S2 activation of NOP. In this fraction, neither cytochrome P450 nor some enzymatic activities depending on cyt-P450 (aniline hydroxylase and aminopyrine demethylase) were detected. Therefore, the enhancement of NOP mutagenic potency by S2 is independent of the mixed-function oxidase system. On the other hand, inhibitors of the peroxidase activity such as N-acetyl-p-aminophenol caused a partial inhibition of S2 activation of NOP. Likewise, diethyldithiocarbamate produced both a reduction of the S2 peroxidase activity in biochemical assays and a partial inhibition of S2 activation of NOP. Moreover, it was possible to find a direct correlation between the activity of peroxidase per plate of both the S2 fraction and horseradish peroxidase and the number of revertants induced by NOP in the TA98 strain. On the basis of these results, we report that a HRP-like peroxidase activity must be the main pathway of NOP activation by the plant metabolic activation system studied in this work.

Biotransformation↗
PubMed1994

Histological evolution of chronic hepatitis C. Factors related to progression.

We have evaluated the histological progression of liver disease in 29 untreated patients with chronic hepatitis C. All patients were positive to antibodies to hepatitis C virus by ELISA2 and RIBA2. Two liver biopsies were carried out for each patient, with an interval ranging between 12 and 126 months (mean 50.2 +/- 30.7). In all cases the usual histological classification was applied and the histological activity index scoring system according to Knodell et al. was determined. Fifteen cases worsened (51.7%), 12 cases showed no histological changes (41.4%) and two patients improved (6.9%). Cirrhosis was found in five patients (18.5%) in the second liver biopsy. Epidemiological, clinical, biochemical and histological progression and the group with impairment in liver histology. Factors related to histological worsening were: more advanced age (p = 0.002), high levels of aspartate aminotransferase (p = 0.04), high global histological activity index (p = 0.03) and piecemeal necrosis and bridging necrosis scores (p = 0.02) at first biopsy. The histological activity index can be applied to assess the natural history of chronic viral hepatitis, and is a good tool to evaluate the prognosis. Thus chronic hepatitis C virus infection is a histologically progressive disease in at least half the cases.

Adult↗