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Biomedical subjects

Lars Ove Dragsted

Publications and source records attributed to Lars Ove Dragsted.

7 recordsLinked to original sources
PubMed2006

[Selenium and health].

Selenium is an essential micronutrient. The average selenium intake in Danish adults is close to the recommended level of 40-50 mg/day. There is no scientific documentation showing that an increased selenium intake will result in disease prevention. However, a preventive effect on some cancers and hearth disease cannot be ruled out. Fortification of foods via increased selenium content in fertilizers is a possible way of increasing selenium intake. The tolerable upper intake level of 60 mg/day in children 1-3 years old must not be exceeded, which makes fortification difficult.

Adult↗
PubMed2006

Carbohydrate digestibility predicts colon carcinogenesis in azoxymethane-treated rats.

The purpose of this study was to compare the effect of carbohydrate structure and digestibility on azoxymethane (AOM)-induced colon carcinogenesis. Five groups of male Fischer 344 rats each comprising 30 animals were injected with AOM and fed a high-fat diet with 15% of various carbohydrates. The carbohydrate sources used were sucrose, cornstarch (a linear starch, reference group), potato starch (a branched starch), a short-chained oligofructose (Raftilose), and a long-chained inulin-type fructan (Raftiline). An interim sacrifice was performed after 9 wk to investigate markers of carbohydrate digestibility, including caecal fermentation (caecum weight and pH) and glucose and lipid metabolism [glucose, fructoseamine, HbA1c, triglycerides, and insulin-like growth factor (IGF) 1]. In addition potential early predictors of carcinogenicity [cell proliferation and aberrant crypt foci (ACF)] at 9 wk and their correlation to colon cancer risk after 32 wk were investigated. Tumor incidence was significantly reduced in animals fed oligofructose, and the number of tumors per animal was significantly reduced in animals fed inulin and oligofructose at 32 wk after AOM induction compared to the reference group fed sucrose. Increased caecum weight and decreased caecal pH were seen in groups fed oligofructose, inulin, and potato starch. Plasma triglyceride was decreased in rats fed oligofructose and inulin. Cell proliferation was increased in the proximal colon of rats fed sucrose, oligofructose, and inulin, and the number of cells per crypt decreased in rats fed oligofructose and inulin. The total number of ACF's was unaffected by treatment, and the size and multiplicity of ACF was unrelated to tumor development. It was concluded that less digestible carbohydrates with an early effect on caecum fermentation and plasma triglyceride decreased subsequent tumor incidence and multiplicity. This was unrelated to ACF, cell proliferation, and other markers of glucose and lipid metabolism.

Animals↗
PubMed2004

Effects of sucrose and cornstarch on 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced colon and liver carcinogenesis in F344 rats.

The purpose of the present study was to compare the effect of sucrose and cornstarch on colon and liver carcinogenesis induced by 0.02% of the food-borne carcinogen 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) in the feed. Male F344 rats were allocated to four groups. Two groups were fed diets high in either cornstarch (68%) or sucrose (34% sucrose/34% cornstarch) and were initiated with IQ. The remaining two groups received the same two diets but did not receive any IQ. In both liver and colon, administration of IQ resulted in a higher level of DNA adducts. In animals not dosed with IQ, sucrose increased the adduct level in both organs but to a lower level than IQ. However, simultaneous administration of IQ and sucrose did not further increase the adduct level. Both IQ and sucrose increased the expression of the DNA-repair enzyme ERCC1 in the liver. In the colon, the number of large and medium aberrant crypt foci (ACF) of the group fed IQ and cornstarch was significantly higher than that in the other groups. There was no statistically significant difference in any tumour incidence in IQ dosed-animals fed either cornstarch or sucrose. In conclusion, no difference in effect on liver carcinogenesis was seen between sucrose and cornstarch-based diets, however, the number of tumours per animal tended to be slightly higher in the rats fed cornstarch (P = 0.08). Cornstarch enhanced ACF development induced by IQ when compared to sucrose whereas due to a low intestinal tumour incidence no correlation to diet and tumour incidence could be established.

Animals↗
PubMed2004

The citrus-derived flavonoid naringenin exerts uterotrophic effects in female mice at human relevant doses.

Gavage administration of the citrus flavonoid naringenin, 3',4,5,7-tetrahydroxyflavanon for 4 consecutive days, to immature female mice (postnatal day 17-20) at 4 or 100 mg/kg b.wt. significantly increased uterine weights 3 and 4 times, respectively. Analysis of uterine oestrogen receptor alpha revealed that naringenin significantly increased the cytosolic concentration of oestrogen receptor alpha, whereas in nuclei the oestrogen receptor alpha concentration was significantly decreased as compared to the solvent control. This was in contrast to the positive control 17 beta-oestradiolacetate which acted as a true oestrogen by increasing the concentration of both total and nuclear oestrogen receptor alpha. Both naringenin and 17 beta-oestradiolacetate, however, significantly, induced nuclear oestrogen receptor alpha in the liver, suggesting a tissue specific effect of naringenin on oestrogen receptor alpha distribution. In order to investigate the tissue levels at which the uterotrophic effect was observed, the distribution of an oral dose of tritiated naringenin (4 mg/kg) was investigated in 3-week-old female mice. The radioactivity content (ng naringenin equivalents/g tissue) was found to be highest in the gastrointestinal-tract, followed by the kidneys and liver. Uterus and ovaries were also found to contain relatively high and approximately equal amounts of naringenin. The concentration of naringenin in uterus and ovaries was found to be ten times higher as compared to the mammary tissue. The urinary excretion of more than 25% of the administered dose, within 8 hr after dosing indicated that naringenin is absorbed extensively in mice. The plasma concentration of 0.5 microM found in the present study is similar to the peak plasma concentration of naringenin (0.6 microM) observed in man following ingestion of 400-760 ml of orange juice (Erlund et al. 2001). This could be taken to suggests that ingestion of orange juice and other citrus fruits and juices may give rise to sufficiently high tissue levels of naringenin in man to exert a biological effect.

Administration, Oral↗
PubMed2003

In vitro antioxidant activities of edible artichoke (Cynara scolymus L.) and effect on biomarkers of antioxidants in rats.

Artichoke (Cynara scolymus L.), an edible vegetable from the Mediterranean area, is a good source of natural antioxidants such as vitamin C, hydroxycinnamic acids, and flavones. The antioxidant activity of aqueous-organic extracts of artichoke were determined using three methods: (a) free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) scavenging, (b) ferric-reducing antioxidant power (FRAP), and (c) inhibition of copper(II)-catalyzed in vitro human low-density lipoprotein (LDL) oxidation. In addition, the present study was performed to investigate the ability of the edible portion of artichoke to alter in vivo antioxidative defense in male rats using selected biomarkers of antioxidant status. One gram (dry matter) had a DPPH(*) activity and a FRAP value in vitro equivalent to those of 29.2 and 62.6 mg of vitamin C and to those of 77.9 and 159 mg of vitamin E, respectively. Artichoke extracts showed good efficiency in the inhibition in vitro of LDL oxidation. Neither ferric-reducing ability nor 2,2'-azinobis(3-ethylbenzothiazolin-6-sulfonate) radical scavenging activity was modified in the plasma of the artichoke group with respect to the control group. Among different antioxidant enzymes measured (superoxide dismutase, gluthatione peroxidase, gluthatione reductase, and catalase) in erythrocytes, only gluthatione peroxidase activity was elevated in the artichoke group compared to the control group. 2-Aminoadipic semialdehyde, a protein oxidation biomarker, was decreased in plasma proteins and hemoglobin in the artichoke-fed group versus the control group. In conclusion, the in vitro protective activity of artichoke was confirmed in a rat model.

Animals↗
PubMed2003

DNA adduct formation and oxidative stress in colon and liver of Big Blue rats after dietary exposure to diesel particles.

Exposure to diesel exhaust particles (DEP) via the gastrointestinal route may impose risk of cancer in the colon and liver. We investigated the effects of DEP given in the diet to Big Blue rats by quantifying a panel of markers of DNA damage and repair, mutation, oxidative damage to proteins and lipids, and antioxidative defence mechanisms in colon mucosa cells, liver tissue and the blood compartment. Seven groups of rats were fed a diet with 0, 0.2, 0.8, 2, 8, 20 or 80 mg DEP/kg feed for 21 days. DEP induced a significant increase in DNA strand breaks in colon and liver. There was no effect on oxidative DNA damage (8-oxodG) in colon or liver DNA or in the urine. However, the mRNA expression of OGG1, encoding an enzyme involved in repair of 8-oxodG, was increased by DEP in both liver and colon. DNA adduct levels measured by 32P-post-labelling were elevated in colon and liver, and the expression of ERCC1 gene was affected in liver, but not in colon. In addition to these effects, DEP exposure induced apoptosis in liver. There was no significant change in mutation frequency in colon or liver. The levels of oxidative protein modifications (oxidized arginine and proline residues) were increased in liver accompanied by enhanced vitamin C levels. In plasma, we found no significant effects on oxidative damage to proteins and lipids, antioxidant enzymes or vitamin C levels. Our data indicate that gastrointestinal exposure to DEP induces DNA adducts and oxidative stress resulting in DNA strand breaks, enhanced repair capacity of oxidative base damage, apoptosis and protein oxidation in colon mucosa cells and liver.

Animals↗