| Selenium is an essential trace element to animal and human nutrition. Its functions include improving immunity, preventing cancer, resisting free radicals, postponing aging, detoxification from some heavy metals, and preventing some local epidemic etc. Selenium deficiency or potential deficiency is very common and serious in the world. In China, about 72% of the territory is short of selenium, people there suffer form selenium deficiency which is no benefit to health. In recent years, epidemiology dates and experimental studies indicate that selenium deficiency shows positive correlation with tumor occurring and selenium supplementation can prevent and/or reduce the incidence of naturally occurring and both chemically and virally induced cancer. Therefore, effect and mechanism study of selenium on tumor has become an important problem.Selenium-enriched malt is an organic selenium-enriched product which translated sodium selenite into organic selenium by malt growth. Comparing with inorganic selenium, selenium-enriched malt has the merits of low toxicity, high bioavailability, sample techniques, low cost, high nutrition value and only a little environmental pollution. In this experiment, selenium-enriched malt was cultivated and used as selenium sources, and its effect on the progress of hepatocarcinogenesis in rats was studied and its mechanisms on lipid peroxidation, cell cycle, apoptosis, angiogenesis were discussed.Test 1 Study on the cultivating of selenium-enriched malt and its selenium content.Cultivating of selenium-enriched malt and the determination method of its selenium content were investigated in this experiment. Seeds of wheat were soaked in different concentration of selenium from sodium selenite and selenium content in malt was determinated and the malt growth performance was observed under different conditions. The optimum conditions for the determination and the effects of digest reagents on digestion of samples and the interference from foreign ions on selenium of hydride generation atomic fluorescence spectrometry(HG-AFS) were briefly discussed and the method was compared withfluorospectrophotemeter. It demonstrated that the optimal condition of cultivating selenium-enriched malt was that seeds of wheat soaked in 250mg-L~-1 sodium selenite about 24 hours, then cultivated under 24 °C for five days. The detection limit of HG-AFS was 0.167μg.L~-1'. The recoveries of the method were 94.1%~101.6% and RSD 1.203%. The method was convenient, quick and accurate.Test 2 Effects of selenium-enriched malt on hepatocarcinogenesis induced by diethylnitrosamine in rats. The effects of selenium-enriched malt on experimental hepatocarcinogenesis induced by diethylnitrosamine(DEN) in rats were observed. Two hundred and twenty-five healthy male SD rats weighed 120~150g were randomly divided into six groups. Twenty-five rats in group I were fed with diet containing 0.lmg-kg~-1 selenium as sodium selenite, designed as normal control; forty rats in group II were fed with diet containing O.lmg.kg~-1 selenium as sodium selenite, designed as model control, group III-VI with forty rats each were fed with diet containing 0.3, 1.0, 3.0mg.kg~-1 selenium as selenium-enriched malt and 3.0mg-kg~-1 selenium as sodium selenium respectively. Rats in group II -VI with hepatocarcinoma was induced by drinking the water with 100mg-L~-1 diethylnitrosamine (DEN) for sixteen weeks. The experiment was lasted eighteen weeks. During the hepatocarcinogenesis, body weight, pathological changes of liver and alanine amiotransterase (ALT), alkaline phosphatase (ALP), albumin (ALB), γ-glutamyltransferase (γ-GT), glutathione-S-transferase (GST) in plasma were observed. When 18 weeks have passed, the rats were killed and hepatoma nodules, body weight, liver weight, ratio of liver/body weight and hepatoma incidence were recorded. The results indicated that pathological changes of liver, hepatoma nodules, ratio of liver/body weight, hepatoma incidence and plasma ALT, ALP, γ-GT, GST activities in the groups of selenium-enriched malt were lower or sig...
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