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Articles by H Sakamoto
Total Records ( 2 ) for H Sakamoto
  T Kohno , R Kakinuma , M Iwasaki , T Yamaji , H Kunitoh , K Suzuki , Y Shimada , K Shiraishi , Y Kasuga , G. S Hamada , K Furuta , K Tsuta , H Sakamoto , A Kuchiba , S Yamamoto , Y Kanai , S Tsugane and J. Yokota
 

Estrogen has been indicated to play an etiological role in the development of lung adenocarcinoma (ADC), particularly bronchioloalveolar carcinoma (BAC), a type of ADC that develops from a benign adenomatous lesion, atypical adenomatous hyperplasia (AAH). Polymorphisms in the CYP19A1 gene cause interindividual differences in estrogen levels. Here, 13 CYP19A1 single-nucleotide polymorphisms (SNPs) were examined for associations with lung AAH risk. AAH is detected as ground-glass opacity (GGO) by computed tomography (CT) examination, and this study consisted of 100 individuals diagnosed with GGO in their lungs among 3088 CT-based cancer screening examinees and 424 without. Minor allele carriers for the rs3764221 SNP showed an elevated risk for GGO [odds ratio (OR) = 1.72, P = 0.017]. Associations of this SNP with risks for lung AAH and BAC in the lungs were next examined using 359 ADC cases whose resected lung lobes were subjected to a histological examination for AAH accompaniment and the presence of BAC components and 330 controls without cancer. The ORs were also increased for lung ADC accompanied by AAH (OR = 1.74, P = 0.029) as well as lung ADC with BAC components (OR = 1.41, P = 0.091). The minor allele was associated with an increased circulating estradiol level (P = 0.079) in a population of 363 postmenopausal women without cancer. These results indicate that CYP19A1 polymorphisms are involved in the risk for lung AAH and BAC in the lungs by causing differences in estrogen levels.

  K Akita , N Hieda , N Baba , S Kawaguchi , H Sakamoto , Y Nakanishi , M Yamanishi , K Mori and T. Toraya
 

The methods of homologous high-level expression and simple large-scale purification for coenzyme B12-dependent ethanolamine ammonia-lyase of Escherichia coli were developed. The eutB and eutC genes in the eut operon encoded the large and small subunits of the enzyme, respectively. The enzyme existed as the heterododecamer 6β6. Upon active-site titration with adeninylpentylcobalamin, a strong competitive inhibitor for coenzyme B12, the binding of 1 mol of the inhibitor per mol of the β unit caused complete inhibition of enzyme, in consistent with its subunit structure. EPR spectra indicated the formation of substrate-derived radicals during catalysis and the binding of cobalamin in the base-on mode, i.e. with 5,6-dimethylbenzimidazole coordinating to the cobalt atom. The purified wild-type enzyme underwent aggregation and inactivation at high concentrations. Limited proteolysis with trypsin indicated that the N-terminal region is not essential for catalysis. His-tagged truncated enzymes were similar to the wild-type enzyme in catalytic properties, but more resistant to p-chloromercuribenzoate than the wild-type enzyme. A truncated enzyme was highly soluble even in the absence of detergent and resistant to aggregation and oxidative inactivation at high concentrations, indicating that a short N-terminal sequence is sufficient to change the solubility and stability of the enzyme.

 
 
 
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