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951.
952.
Octylphenols, widely used in a variety of detergents and plastics, are known to exhibit estrogenicity in vivo. The details of their metabolism are needed to better understand the endocrine disruptions. We have previously shown that alkylphenols, having short alkyl chains, are glucuronidated and readily excreted into the bile from the liver, while 4-n-nonylphenol, having longer alkyl chains, remains as the alkylphenol's glucuronide in the tissue. This study elucidated the dependence of the metabolism on the shape of the alkyl chains by comparing 4-n-octylphenol and 4-tert-octylphenols in a perfused rat liver. Both octylphenols were highly glucuronidated by the liver microsomal fractions. The Vmax value of 4-tert-octylphenol glucuronidation was twice as high as that of 4-n-octylphenol in the liver microsomes. On the other hand, the Km values, being measures of enzymatic activity against these chemicals, were similar. 4-n-Octylphenol and 4-tert-octylphenol were both glucuronidated by a UDP-glucuronosyltransferase isoform, UGT2B1, expressed in the liver. In the liver perfusion, almost all of the 4-n-octylphenol perfused was metabolized directly to the glucuronide, whereas a portion of 4-tert-octylphenol was hydroxylated and then glucuronidated. The glucuronide of 4-n-octylphenol accumulated in the liver tissue in the same manner as 4-n-nonylphenol, but 4-tert-octylphenol and the hydroxylated metabolites were excreted readily into the bile. Only a small amount of 4-n-octylphenol-glucuronide and glucuronides of 4-tert-octylphenol and its hydroxylated metabolites could be excreted into the bile of Eisai hyperbilirubinemic rats (EHBR). These animals are deficient in xenobiotic conjugate transporter, multidrug resistance-associated protein (MRP-2), indicating that the glucuronides of both octylphenols are transported by MRP-2. These results indicate that the differences in metabolism of these octylphenols are due to the shape of their alkyl chains, suggesting that the estrogenic activities of not only the parent chemicals but also these metabolites must be taken into consideration. 相似文献
953.
954.
Hepatocyte nuclear factor 4alpha contributes to thyroid hormone homeostasis by cooperatively regulating the type 1 iodothyronine deiodinase gene with GATA4 and Kruppel-like transcription factor 9 下载免费PDF全文
955.
Raman H Ryan PR Raman R Stodart BJ Zhang K Martin P Wood R Sasaki T Yamamoto Y Mackay M Hebb DM Delhaize E 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(3):343-354
Allele diversities of four markers specific to intron three, exon four and promoter regions of the aluminum (Al) resistance
gene of wheat (Triticum aestivum L.) TaALMT1 were compared in 179 common wheat cultivars used in international wheat breeding programs. In wheat cultivars released during
the last 93 years, six different promoter types were identified on the basis of allele size. A previous study showed that
Al resistance was not associated with a particular coding allele for TaALMT1 but was correlated with blocks of repeated sequence upstream of the coding sequence. We verified the linkage between these
promoter alleles and Al resistance in three doubled haploid and one intercross populations segregating for Al resistance.
Molecular and pedigree analysis suggest that Al resistance in modern wheat germplasm is derived from several independent sources.
Analysis of a population of 278 landraces and subspecies of wheat showed that most of the promoter alleles associated with
Al resistance pre-existed in Europe, the Middle East and Asia prior to dispersal of cultivated germplasm around the world.
Furthermore, several new promoter alleles were identified among the landraces surveyed. The TaALMT1 promoter alleles found within the spelt wheats were consistent with the hypothesis that these spelts arose on several independent
occasions from hybridisations between non-free-threshing tetraploid wheats and Al-resistant hexaploid bread wheats. The strong
correlation between Al resistance and Al-stimulated malate efflux from the root apices of 49 diverse wheat genotypes examined
was consistent with the previous finding that Al resistance in wheat is conditioned primarily by malate efflux. These results
demonstrate that the markers based on intron, exon and promoter regions of TaALMT1 can trace the inheritance of the Al resistance locus within wheat pedigrees and track Al resistance in breeding programmes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
956.
957.
Tanisaka H Kizaka-Kondoh S Makino A Tanaka S Hiraoka M Kimura S 《Bioconjugate chemistry》2008,19(1):109-117
Nonionic amphiphilic copolypeptides, which were composed of hydrophilic poly(sarcosine) and hydrophobic poly(gamma-methyl L-glutamate) blocks, were synthesized with varying chain lengths of the blocks. The polypeptides having a suitable hydrophilic and hydrophobic balance were found to form vesicular assemblies of 100 nm size in buffer, which was evidenced by the TEM observation, the DLS analysis, and the encapsulation experiment. The genuine peptide vesicles, peptosomes, were labeled with a near-infrared fluorescence (NIRF) probe. In vivo retention in blood experiment showed long circulation of the peptosome in rat blood as stable as the PEGylated liposome. NIRF imaging of a small cancer on mouse by using the peptosome as a nanocarrier was successful due to the EPR effect of the peptosome. Peptosome is shown here as a novel excellent nanocarrier for molecular imaging. 相似文献
958.
959.
Hiroki Nishimura Gen Komaki Tetsuya Ando Toshihiro Nakahara Takakazu Oka Keisuke Kawai Toshihiko Nagata Aya Nishizono Yuri Okamoto Kenjiro Okabe Masanori Koide Chikara Yamaguchi Satoshi Saito Kazuyoshi Ohkuma Katsutaro Nagata Tetsuro Naruo Masato Takii Nobuo Kiriike Toshio Ishikawa 《BioPsychoSocial medicine》2008,2(1):1-8
Background
Over the last five to ten years there has been an increase in psychosomatic complaints (PSC) in Swedish children. The objective of the study was to examine the relation between PSC and sense of coherence (SOC). 相似文献960.
He XS Holmes TH Sasaki S Jaimes MC Kemble GW Dekker CL Arvin AM Greenberg HB 《PloS one》2008,3(7):e2574