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- Björnstedt, M., et al.
(författare)
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Selenium and the thioredoxin and glutaredoxin systems
- 1997
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Ingår i: Biomedical and environmental sciences. - : Elsevier. - 0895-3988 .- 2214-0190. ; 10:2-3, s. 271-279
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Tidskriftsartikel (refereegranskat)abstract
- Thioredoxin (Trx) is a small ubiquitous dithiol protein which together with the FAD-containing enzyme thioredoxin reductase (TR) and NADPH (the Trx system) is a hydrogen donor for ribonucleotide reductase essential for DNA synthesis and a general protein disulfide reductase involved in redox regulation. Selenite, selenodiglutathione (GS-Se-SG) and selenocystine are efficiently reduced by thioredoxins and also directly by NADPH and mammalian TR but not by the E. coli enzyme. Incubation of selenite or GS-Se-SG with the Trx system or with mammalian TR results in a rapid formation of selenide, which by redox cycling with oxygen may cause a large non-stoichiometric oxidation of NADPH. Selenocystine is efficiently reduced into two molecules of the selenol amino acid selenocysteine by mammalian TR with a K(m)-value (6 mumol.L-1) and a high turnover number (kappa cat 3200 min-1) almost identical to the natural substrate Trx-S2. TR also directly reduces lipid hydroperoxides and this peroxidase reaction is strongly stimulated by the presence of catalytic amounts of free selenocysteine. Glutaredoxin (Grx) which catalyzes GSH-dependent disulfide reduction also via a redox-active disulfide and Trx are both efficient electron donors to the human plasma glutathione peroxidase providing a mechanism by which human plasma glutathione peroxidase may reduce hydroperoxides in an environment almost free from glutathione. Selenate is reduced by Grx and Trx in the presence of GSH. The DNA-binding of the transcription factor AP-1 is strongly inhibited by GS-Se-SG and selenite. Furthermore, selenide formed by TR-mediated reduction of selenite and GS-Se-SG inhibits lipoxygenase and changes the electron spin resonance spectrum of the active site iron. Mammalian TR with two subunits of 57 kDa has recently been cloned and shown to be homologous to glutathione reductase. The rat enzyme contains a selenocysteine residue in a unique Cterminal position and a conserved SECIS sequence directing insertion of the selenocysteine. The discovery of selenocysteine in mammalian TR may explain the broad substrate specificity of the enzyme and the requirement of selenium for cell proliferation.
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| 2. |
- Han, Jing, et al.
(författare)
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Changing grains for the prevention and treatment of Kashin-Beck disease in children : a Meta-analysis
- 2015
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Ingår i: Biomedical and environmental sciences. - : Chinese Center for Disease Control and Prevention. - 0895-3988 .- 2214-0190. ; 28:4, s. 308-311
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the efficacy of changing grains on the prevention and treatment of Kashin-Beck Disease (KBD) in children, community-based trials were acquired from seven electronic databases (up to July 2014). As a result, the methodological quality of the six trials that have been included into our analysis was low. The pooled ORs favoring the prevention and treatment effects of changing grains were 0.15 (95% CI: 0.03-0.70) and 2.13 (95% CI: 1.44-3.16) respectively by meta-analysis. Subgroup analysis demonstrated the pooled OR favoring treatment effect of exchanging grains rather than drying grains both compared with endemic grains. The results showed that changing grains had obvious effects on the prevention and treatment of KBD in children. However, the evidences were limited by the potential biases and confounders. Large and well-designed trials are still needed.
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| 3. |
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| 4. |
- Yu, Fang Fang, et al.
(författare)
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Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test
- 2017
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Ingår i: Biomedical and environmental sciences. - 0895-3988 .- 2214-0190. ; 30:11, s. 851-854
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Tidskriftsartikel (refereegranskat)abstract
- Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone, knee joints, and costal cartilage) were significantly higher than those in the heart, liver, and kidneys (P < 0.05). The relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone and costal cartilage) were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%.
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| 5. |
- Zheng, Yi Wu, et al.
(författare)
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Indoor Allergen Levels and Household Distributions in Nine Cities Across China
- 2015
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Ingår i: Biomedical and environmental sciences. - 0895-3988 .- 2214-0190. ; 28:10, s. 709-717
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Chinese allergic subjects have high levels of sensitization to house dust mite (HDM) and other indoor allergens. This study quantifies common indoor allergen levels in Chinese households.METHODS: Dust samples were collected from nine cities. Major allergens Der p 1 and Der f 1 from Dermatophagoides pteronyssinus and D. farinae, and specific antigens of Blomia tropicalis, Tyrophagus putrescentiae, Acarus siro, and cockroach species Blattella germanica and Periplaneta americana were measured by ELISA.RESULTS: HDM allergens were found in dust samples from bedding in 95% of the Chinese households. The median levels varied from <0.006 to 9.2 µg/g of dust, depending on the city. The percentages of households having HDM allergen levels associated with the risk of developing allergy sensitization and asthma were 65% and 25%, respectively. Specific antigens of the storage mite and cockroach were only found in samples from the southern and tropical regions of China. Levels of mite allergens were generally higher in samples from bedding compared to samples from the living room, even for storage mites, whereas levels of cockroach antigens were higher in the living room samples.CONCLUSION: HDM allergens are present in bedding dust samples from most Chinese households. Cities in southern and central China have relatively high levels of HDM major allergens compared to cities in northern and western China. Antigens of storage mites and cockroaches are not as common as HDM allergens.
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