Emi Yamaoka

Hiroshima University, Hiroshima-shi, Hiroshima-ken, Japan

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Publications (4)7.93 Total impact

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    ABSTRACT: Amplification of neuroblastoma derived (avian) v-myc myelocytomatosis viral related oncogene (MYCN) is an important risk-stratified indicator in neuroblastoma. To evaluate the feasibility of noninvasive measurement of MYCN amplification, we analyzed MYCN amplification in stored blood plasma samples. We used quantitative real-time PCR to determine MYCN copy numbers in plasma-derived DNA of 10 healthy volunteers and 50 neuroblastoma cases. The copy number was calculated as the ratio of copies of MYCN to those of a reference gene. Plasma samples obtained after surgery or neoadjuvant therapy were also analyzed in five cases and four cases, respectively. In 34 neuroblastoma cases, MYCN was non-amplified in both tumor tissue and blood plasma. In 16 neuroblastoma cases, MYCN was amplified in both tumor tissue and blood plasma; 13 of the 16 cases showed poor outcomes. MYCN amplification was undetectable in blood plasma shortly after surgery or neoadjuvant therapy. The correlation coefficient between MYCN copy numbers in tumor tissue and in blood plasma was approximately 0.9. We can detect MYCN amplification of tumor tissue noninvasively and quantitatively by measuring the MYCN copy number in blood plasma. Determination of MYCN copy number in plasma may be useful when evaluating surgery and neoadjuvant chemotherapy.
    Pediatric Surgery International 09/2013; · 1.22 Impact Factor
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    ABSTRACT: Mesenchymal stem cells (MSCs) could be useful for regenerative medicine because they can beharvested easily from the bone marrow of living donors and the cells can be differentiated into adipogenic, osteogenic, and chondrogenic lineages in vitro. To apply MSCs for the medical treatment of human diseases as regenerative medicine, detailed experimental characterization of the cells is required. Recently, a New World primate, the common marmoset (Callithrix jacchus), has been widely used as a new human disease model because of its ease of handling and breeding. Although common marmoset MSCs have been established and will be used in preclinical studies of regenerative medicine, the characteristics of these cells remain unclear. Aiming to characterize common marmoset MSCs further, we harvested common marmoset bone marrow-derived cells (cmBMDCs) from the femurs of newborn males. We revealed that the morphology of the cells was similar to common marmoset fibroblasts, and extracellular matrix components, such as gelatin and fibronectin, were effective for their proliferation and formation of colony-forming unit fibroblasts. Furthermore, we were able to differentiate cmBMDCs into adipocytes, osteocytes, and chondrocytes in vitro, and they expressed the MSCmarkers CD44, CD73, CD90, and CD105, but their expression decreased with increasing passage number. The data demonstrate that cmBMDCs exhibit characteristics of MSCs and thus it would be beneficial to use these cells in preclinical studies.
    Folia Histochemica et Cytobiologica 01/2013; 51(4):292-9. · 1.10 Impact Factor
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    ABSTRACT: Previous reports suggested that the urine trypsinogen 2 (U-TRP2) test might be a valuable method for the diagnosis of postoperative pancreatitis after pancreatic surgery. We hypothesize that the elevation of U-TRP2 level after pancreaticoduodenectomy (PD) could be associated with the occurrence of postoperative pancreatic fistula (POPF). A total of 130 consecutive patients undergoing PD with duct-to-mucosa pancreaticogastrostomy were included. Urine samples for evaluation of U-TRP2 levels were collected prospectively. Risk factors for POPF were evaluated using univariate and multivariate analyses. Of 130 patients, 19 developed POPF; grade A in 14 (11%), grade B in 3 (2%), and grade C in 1 (1%). Univariate analysis demonstrated that a nonobstructed main pancreatic duct, a pancreatic duct less than 3 mm, soft texture of the pancreatic gland, a PD with antrectomy, PD with hepatic resection, hyperamylasemia, and elevation of U-TRP2 levels (>50 μg/L) were significantly associated with POPF (P < 0.05). By multivariate analysis, elevation of U-TRP2 levels (odds ratio = 4.544, P = 0.029) was the only independent risk factor that correlated with POPF. Elevation of U-TRP2 level is an independent risk factor for POPF after PD. Elevated U-TRP2 level might be the consequence of the postoperative pancreatitis, and postoperative pancreatitis may play an important role in the pathogenic mechanism of POPF after PD.
    Pancreas 02/2012; 41(6):876-81. · 2.95 Impact Factor
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    ABSTRACT: The low percentage of human mesenchymal stem cells (hMSCs) in bone marrow necessitates their in vitro expansion prior to clinical use in regenerative medicine. We evaluated the effect of long-term culture of hMSCs on telomere length and transformation capacity by TERT transfection. hMSCs were isolated from the bone marrow aspirates of 24 donors and cultured with fibroblast growth factor-2 (FGF-2). Six cell lines with >500 population doubling levels were considered immortalized. TERT was transfected into two of the six lines for a comparison of telomere length, telomerase activity, differential capacity, colony formation capacity in soft agar and tumorigenicity in immunodeficient (NOD-SCID) mice. hMSC lines exhibited elongated telomeres without the activation of telomerase and retained multi-lineage differentiation potential upon chondrogenic or adipogenic differentiation, while non-immortalized hMSCs showed a marked reduction in telomere length in the differentiation process. Immortalized hMSCs showed anchorage-independence and formed tumors in NOD-SCID mice. Histologically, these tumors consisted of differentiated cells such as fat tissue and cartilage. Two TERT-transfected hMSC lines showed high rates of tumor formation in NOD-SCID mice. These tumors were histologically similar to teratocarcinoma without differentiated cells. These cells may provide a model for the origin of cancer stem cells from adult stem cells, and indicate the possibility that telomerase activation has a major role in the malignant transformation of human stem cells. These data suggest that adult hMSCs have a potential for neoplastic transformation and have implications for the use of hMSCs in tissue engineering and regenerative medicine.
    International Journal of Oncology 07/2011; 39(1):5-11. · 2.66 Impact Factor