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- Sjödin, P, et al.
(författare)
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Effect of dietary fiber on the disposition and excretion of a food carcinogen (2-14C-labeled MeIQx) in rats
- 1992
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Ingår i: Nutrition and Cancer. - : Informa UK Limited. - 0163-5581 .- 1532-7914. ; 17:2, s. 139-151
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Tidskriftsartikel (refereegranskat)abstract
- We studied to what extent dietary fiber may affect uptake, retention, and excretion of a food carcinogen (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, MeIQx) occurring in fried meat. Four diets--one fiber-free control and three containing either insoluble dietary fiber isolated from sorghum (100 g/kg) and wheat bran (100 g/kg) or the highly soluble pectin (50 g/kg)--were investigated. The fiber diets were given in amounts of 10 g/day to rats. Thus, each rat received 1 or 0.5 g fiber and 100 micrograms 2-14C-labeled MeIQx uniformly mixed in its daily diet. A 4-day adaptation period with unlabeled MeIQx was followed by a 5-day experimental period with 14C-labeled MeIQx, during which urine and feces were collected separately for analysis of radioactivity and mutagenicity. Furthermore the composition and the fermentability of the dietary fiber were determined. The present study shows that a diet containing fiber, especially fiber isolated from sorghum and wheat bran, affects the excretion pattern of the food carcinogen MeIQx in a manner suggesting a lower uptake and a decreased transit time through the gastrointestinal tract in a more diluted form than a nonfiber diet. Furthermore, less radioactivity was retained in the kidneys with sorghum and wheat bran than with the other two diets. On the other hand, none of these types of dietary fiber affected the retention of the hepatocarcinogen MeIQx in the liver 24 hours after the last oral intake. DNA adducts were formed to a higher extent in the kidney than in the liver. The highest levels were found in animals given the wheat bran diet.
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- Skagerlund, J., et al.
(författare)
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Evaluation of an automatic method to extract the grating coupling coefficient in different types of fabricated DFB lasers
- 1998
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Ingår i: IEEE Journal of Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9197 .- 1558-1713. ; 34, s. 141-146
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Tidskriftsartikel (refereegranskat)abstract
- Distributed feedback (DFB) laser parameters such as grating coupling coefficient, effective indices, facet reflectances, and the phases of facet reflectances have been determined using a method based on least-square fitting of theoretical spectra to measured, subthreshold DFB laser emission spectra. The only inputs needed are geometrical parameters such as length, grating period, and internal grating phase shifts. A larger number of devices have been successfully characterized, and consistent results have been obtained in both 1.3- mu;m multi-quantum-well (MQW) DFB lasers with both facets as-cleaved, and in 1.55- mu;m MQW DFB lasers with no, one, or two facets as-cleaved
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- Wallin, H, et al.
(författare)
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Altered aromatic amine metabolism in epileptic patients treated with phenobarbital
- 1995
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Ingår i: Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. - 1055-9965. ; 4:7, s. 3-771
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Tidskriftsartikel (refereegranskat)abstract
- The fate of carcinogens differs among individuals who have different activities of drug-metabolizing enzymes that are important in activating and detoxifying carcinogens. A drug that profoundly alters the metabolism of the drugs and carcinogens is the anticonvulsive agent phenobarbital. To investigate why epileptic patients appear to have a low risk of cancer of the urinary bladder, and on the basis of the observation that levels of aromatic amine-hemoglobin adducts are strongly associated with various risk factors for cancer at that site, we determined aromatic amine-hemoglobin adducts in 62 epileptic patients as a surrogate measure of the reaction of carcinogenic metabolites with DNA in target tissue. Although adducts were detected in all subjects, the levels were proportional to daily tobacco consumption. When the subjects were stratified into groups smoking 20 g tobacco/day or more, smoking <20 g/day, and not smoking, an effect of medication was detected. Epileptic patients treated chronically with phenobarbital or primidone, which is effectively metabolized to phenobarbital, were found to have lower levels of 4-aminobiphenyl adducts than patients on the other treatment (P = 0.02; ANOVA). In nonsmokers, no effect of medication could be demonstrated above background variation; however, an increasing effect was seen with tobacco consumption with only one-half the increase in adducts per g of tobacco smoked as epileptic patients on other treatment. The difference in the increases (slopes of regression lines) was highly significant statistically. This reduction in the level of hemoglobin-aromatic amine adducts is probably due to induction of detoxification enzymes in the patients treated with phenobarbital.
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