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Articles by S. Y Park
Total Records ( 3 ) for S. Y Park
  S Rajan , S. C Eames , S. Y Park , C Labno , G. I Bell , V. E Prince and L. H. Philipson
 

Permanent neonatal diabetes mellitus is a rare form of insulin-requiring diabetes presenting within the first few weeks or months of life. Mutations in the insulin gene are the second most common cause of this form of diabetes. These mutations are located in critical regions of preproinsulin and are likely to prevent normal processing or folding of the preproinsulin/proinsulin molecule. To characterize these mutations, we transiently expressed proinsulin-GFP fusion proteins in MIN6 mouse insulinoma cells. Our study revealed three groups of mutant proteins: 1) mutations that result in retention of proinsulin in the endoplasmic reticulum (ER) and attenuation of secretion of cotransfected wild-type insulin: C43G, F48C, and C96Y; 2) mutations with partial ER retention, partial recruitment to granules, and attenuation of secretion of wild-type insulin: G32R, G32S, G47V, G90C, and Y108C; and 3) similar to (2) but with no significant attenuation of wild-type insulin secretion: A24D and R89C. The mutant insulin proteins do not prevent targeting of wild-type insulin to secretory granules, but most appear to lead to decreased secretion of wild-type insulin. Each of the mutants triggers the expression of the proapoptotic gene Chop, indicating the presence of ER stress.

  S. Y Ryu , S. I Park , B. H Nam , I Kim , C. W Yoo , J. H Nam , K. H Lee , C. H Cho , J. H Kim , S. Y Park , B. G Kim and S. B. Kang
 

Background: This study was to investigate the prognostic significance of clinicopathologic characteristics in patients with clear-cell carcinoma (CCC) of the ovary.

Materials and methods: Two hundred and one patients with CCC of the ovary were registered in the Korean Gynecologic Oncology Group. The Korean Gynecologic Pathology Study Group reviewed the pathological slides centrally, using a universal grading system. The prognostic significances of clinicopathologic factors were evaluated by multivariate analysis.

Results: Most of the patients were diagnosed at an early stage (stage I, 61.3%), and the overall 5-year survival rate was 57%. Early-stage disease showed a favorable prognosis, but advanced diseases showed poor prognosis. Stage of disease was the only significant prognostic factor on multivariate analysis (P < 0.001). However, universal grade and residual tumor also showed prognostic significance on the forward stepwise likelihood ratio test. There was no survival difference observed between patients treated with paclitaxel-based and those treated with platinum-based combination chemotherapy.

Conclusions: The stage, residual tumor, and universal grade were significant prognostic factors in patients with CCC of the ovary. The universal grading system is applicable in determining prognosis of CCC of the ovary. Further clinical trials for optimal chemotherapy are in need.

  N Nakanishi , M. M Rahman , Y Sakamoto , M Miura , F Takeuchi , S. Y Park and M. Tsubaki
 

Cytochromes b561 constitute a novel class of proteins in eukaryotic cells with a number of highly relevant common features including six transmembrane -helices and two haem groups. Of particular interest is the presence of a large number of plant homologues having putative ascorbate- and monodehydroascorbate radical-binding sites. We conducted a diethylpyrocarbonate-modification study employing Zea mays cytochrome b561 heterologously expressed in Pichia pastoris cells. Pre-treatment of cytochrome b561 with diethylpyrocarbonate in oxidized form caused N-carbethoxylation of His86, His159 and Lys83, leading to a drastic inhibition of the electron transfer from ascorbate. The activity was protected by the inclusion of ascorbate during the treatment. However, midpoint potentials of two haem centres did show only slight decreases upon the treatment, suggesting that changes in the midpoint potentials were not the major cause of the inhibition. Present results indicated that Zea mays cytochrome b561 conducted an ascorbate-specific transmembrane electron transfer by utilizing a concerted H+/e transfer mechanism and that the specific N-carbethoxylation of haem axial His86 that would inhibit the removal of a proton from the bound ascorbate was a major cause of the inhibition. On the other hand, Lys83 might be important for an initial step(s) of the fast electron acceptance from ascorbate.

 
 
 
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