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M Roberfroid

Publications and source records attributed to M Roberfroid.

158 records · Page 9Linked to original sources
PubMedDate not supplied

The risks of risk assessment in foods.

This report is the outcome of a workshop organized by the International Life Sciences Institute-European Branch (ILSI Europe), on the "Risks of Risk Assessment in Foods" held on 18 February 1998 in Brussels, Belgium. The meeting discussed Risk Assessment as the principal means by which the European Union evaluates the potential harm arising from the use of existing and new products. The experiences of the parties involved have often shown that the concepts underlying risk assessment are complex and not always fully understood. There is an urgent need to familiarize industry, policy makers and the scientific community with developments in the basic principles and terminology of risk assessment. Therefore, the workshop aimed to review key areas in risk assessment and to provide an open forum for learning and discussion between all interested parties.

Europe↗
PubMedDate not supplied

Biochemical basis for the resistance of guinea-pig and monkey to the carcinogenic effects of arylamines and arylamides.

1. Ag.l.c. assay for N-hydroxy-2-acetamidofluorene has been modified to measure both N-hydroxy-2-acetamidofluorene and N-hydroxy-2-aminofluorene. 2. Like guinea-pig, monkey N-hydroxylates both 2-aminofluorene and 2-acetamido-fluorene. The N-hydroxy metabolites are rapidly further metabolized even in the presence of inhibitors of deacetylase. The exact nature of this further metabolism is still unknown. Preliminary evidence indicates that, at least in the guinea-pig, 7-hydroxy-2-acetamidofluorene may be a metabolite of N-hydroxy-2-acetmidofluorene. 3. 3-Methylcholanthrene, 7,8-benzoflavone and miconazole, which have been shown to inhibit guinea-pig liver microsomal N-hydroxylase, do not significantly inhibit the monkey liver enzyme. 4. 2-Acetamidofluorene, which inhibits the guinea-pig liver microsomal N-hydroxylation of 2-aminofluorene in vitro, activates the enzyme from monkey liver. This activation, which is dose-dependent, appears to be allosteric. 5. Both guinea-pig and monkey are more efficient in N-hydroxylating 2-aminofluorene than 2-acetamidofluorene. The affinity (in term of apparent KM) of the guinea-pig liver enzyme is 4 times greater than the affinity of the monkey liver enzyme.

2-Acetylaminofluorene↗
PubMedDate not supplied

Non-toxic sensitization of cancer chemotherapy by combined vitamin C and K3 pretreatment in a mouse tumor resistant to oncovin.

The effects of combined vitamin C and K3 i.p. injected 3 hours before i.p. administration of single dose of oncovin, to which the ascites liver tumor in mouse (T.L.T.) was completely resistant, were investigated. This pretreatment sensitized the tumor resistant to oncovin, whereas a separate pretreatment with vitamin C or K3 alone was without any effect. This tumor sensitization to the chemotherapy was completely suppressed by catalase pretreatment, thus indicating that hydrogen peroxide generation with subsequent oxidative stress and its consequences may be involved here. Since this sensitization was without any increased general and organ toxicity, its possible introduction into classical protocols of human cancer treatment would be without any supplementary risk.

Animals↗
PubMedDate not supplied

Variations in serum alkaline DNase activity: a possible clinical test for therapeutic prognosis of human tumors.

Previously published histochemical observations indicated that variations in serum alkaline DNase activity (SADA) could be considered as a possible prognostic test for human tumor therapy. In more than 80 cancer patients biochemical measurements of SADA were performed using the spectrophotometrical technique. A decrease of SADA promptly after the beginning of tumor treatment (phase I) may be interpreted as an early sign of therapeutically induced tumor necrosis and as a positive response to the treatment. A delayed regain of SADA (phase II) can predict the long term evolution of the disease. In this phase (II), a regain of SADA up to values higher than the initial value corresponds to a complete tumor regression. If the regain is limited to values lower than the initial value, only a partial tumor regression is seen. No variations of SADA were observed in patients without therapeutic response and with fatal evolution.

Adenocarcinoma↗
PubMedDate not supplied

Potentiation of radiotherapy by nontoxic pretreatment with combined vitamins C and K3 in mice bearing solid transplantable tumor.

BACKGROUND: The effect of intraperitoneal and oral pretreatment with combined vitamins C and K3 on the single dose radiotherapy of a transplantable solid mouse tumor have been investigated. MATERIALS AND METHODS: Groups of mice bearing intramuscularly transplanted liver tumors, were orally and parenterally pretreated with combined vitamins C and K3 and locally irradiated with single doses of 20, 30, or 40 Gy of X-rays. After this treatment tumor dimensions were measured twice weekly and the approximate tumor volume in groups of pretreated vitamins and irradiated mice was compared to the groups of mice only irradiated and to the absolute control groups without any therapy. RESULTS: This nontoxic pretreatment produced statistically significant potentiation of radiotherapy induced by 20 to 40 Gy of X-rays doses in groups of 11 to 20 mice. Combined vitamins C with K3 most probably constitute a redox-cycling system producing hydrogen peroxide and other active oxygen species to which cancer cells are selectively sensitive due to their frequent deficiency in enzymatic defense system against free oxyradicals agression. CONCLUSIONS: A possible introduction of such nontoxic and selective potentiation procedure into classical protocols of human cancer therapy appears to be generally accessible and without any additional risk for patients.

Animals↗