Biomedical subjects

Y Akiyama

Publications and source records attributed to Y Akiyama.

At least 19 recordsLinked to original sources

PubMed2006

Surface functionalization of inorganic nano-crystals with fibronectin and E-cadherin chimera synergistically accelerates trans-gene delivery into embryonic stem cells.

Stem cells holding great promises in regenerative medicine have the potential to be differentiated to a specific cell type through genetic manipulation. However, conventional ways of gene transfer to such progenitor cells suffer from a number of disadvantages particularly involving safety and efficacy issues. Here, we report on the development of a bio-functionalized inorganic nano-carrier of DNA by embedding fibronectin and E-cadherin chimera on the carrier, leading to its high affinity interactions with embryonic stem cell surface and accelerated trans-gene delivery for subsequent expression. While only apatite nano-particles were very inefficient in transfecting embryonic stem cells, fibronectin-anchored particles and to a more significant extent, fibronectin and E-cadherin-Fc-associated particles dramatically enhanced trans-gene delivery with a value notably higher than that of commercially available lipofection system. The involvement of both cell surface integrin and E-cadherin in mediating intracellular localization of the hybrid carrier was verified by blocking integrin binding site with excess free fibronectin and up-regulating both integrin and E-cadherin through PKC activation. Thus, the new establishment of a bio-functional hybrid gene-carrier would promote and facilitate development of stem cell-based therapy in regenerative medicine.

Animals↗

PubMed2006

Hydrodynamics-based gene delivery of naked DNA encoding fetal liver kinase-1 gene effectively suppresses the growth of pre-existing tumors.

Antiangiogenic gene therapy is a promising strategy for cancer treatment, which generally requires highly efficient delivery systems. To date, success of this strategy has depended almost exclusively on the delivery of high titers of viral vectors, which can result in effective transgene expression. However, their cytotoxicity and immunogenicity are a major concern for clinical applications. Recent advances in delivery efficiency of naked DNA could potentially meet the requirement for both high transgene expression and minimal side effects. To investigate whether naked DNA can be used for antiangiogenic cancer therapy, an expression plasmid was generated that encodes a soluble form of fetal liver kinase-1 (Flk-1) gene, a receptor for vascular endothelial growth factor (VEGF). Hydrodynamic injection of this plasmid resulted in close to 0.1 mg/ml of soluble Flk-1 protein in mouse serum and blocked VEGF-driven angiogenesis in matrigel in vivo. The same delivery significantly suppressed the growth of two different pre-existing subcutaneous tumors, Renca renal cell carcinoma and 3LL lung carcinoma. CD31 immunohistochemistry revealed that the tumor-associated angiogenesis was also highly attenuated in soluble Flk-1-treated mice. Thus, expression of genes by hydrodynamics-based gene delivery of naked DNA appears to be a promising approach for antiangiogenic cancer gene therapy.

Animals↗

PubMed2006

Frequent epigenetic silencing of the bone morphogenetic protein 2 gene through methylation in gastric carcinomas.

Recently, it was reported that exogenous bone morphogenetic protein (BMP)-2 acted as an antiproliferative agent in a variety of cell lines, including normal and cancerous gastric cell lines, indicating that BMP-2 plays an important role during cell growth. However, despite the loss of BMP-2 expression in several cancers, the underlying mechanism remains unknown. Epigenetic silencing through DNA methylation is one of the key steps during carcinogenesis. In this study, we found, through analysis by the methylation-specific polymerase chain reaction technique, CpG island methylation of the BMP-2 promoter region in gastric and colon cancer cell lines. BMP-2 mRNA was found to be activated after 5-aza-2'-deoxycytidine treatment of the methylation-positive cells. Moreover, 24 of the 56 (42.9%) gastric cancer tissues exhibited promoter methylation. Immunohistochemical staining revealed that 18 of the 24 (75%) gastric cancer tissues without methylation signals exhibited BMP-2 expression, whereas among 20 cancer tissues with strong methylation signals only four (20%) expressed BMP-2 (P = 0.0003). These findings indicate that BMP-2 methylation is strongly associated with the loss of BMP-2 protein expression in the primary gastric carcinomas. BMP-2 methylation was more often observed in diffuse type (60.7%) than in intestinal type (25%) gastric carcinomas (P = 0.007). Thus, aberrant BMP-2 methylation and the resultant loss of BMP-2 expression may be related to gastric carcinogenesis, particularly in the diffuse type.

Aged↗

PubMed2006

A novel endoscopic marker: safety experiments in the rat stomach.

BACKGROUND AND STUDY AIMS: The study aimed to assess a newly developed endoscopic marker designed to cause only minor inflammatory reactions. MATERIALS AND METHODS: Chitosan and carbon powder were used in the marker substance. The product was a viscoelastic solution, which was injected into the submucosa in rat stomach walls. The tissue reactions were then examined histopathologically. The structure of the injected marker substance was examined with electron microscopy into rat stomach walls. India ink, which is currently used as an endoscopic marker, served as the control. RESULTS: Histopathological examination showed that inflammatory reactions with the novel agent were remarkably mild in the rat organs, while submucosally applied india ink caused severe inflammation in situ. The electron-microscopic findings showed that the carbon particles used were completely spherical in shape and that the carbon in the marker substance was entrapped in the chitosan networks. The india ink was shown to consist of a mixture of fine carbon particles and adhesive additives. CONCLUSIONS: The chitosan-carbon solution appears to be a promising endoscopic marker substance, causing significantly reduced inflammation.

Animals↗

PubMed2006

Aberrant maspin expression in gallbladder epithelium is associated with intestinal metaplasia in patients with cholelithiasis.

OBJECTIVE: Aberrant expression of maspin protein related to DNA hypomethylation in the promoter region is frequently observed in gallbladder carcinomas, whereas the non-tumorous gallbladder epithelium is maspin negative. We investigated maspin expression in non-tumorous gallbladder epithelium in patients with cholelithiasis. METHODS: An immunohistochemical study of maspin expression was performed in 69 patients with cholelithiasis and 30 patients with gastric cancer without cholelithiasis. RESULTS: Immunoreactivity for maspin was observed in focal and patchy regions of the gallbladder epithelium. Positive immunoreactivity for maspin was significantly associated with the presence of intestinal metaplasia in patients with cholelithiasis (p<0.05). CONCLUSION: The high incidence of aberrant maspin expression in both intestinal metaplasia and carcinoma of the gallbladder supports the assumption that intestinal metaplasia of the gallbladder may predispose to gallbladder carcinoma.

Adult↗

PubMed2005

Gene expression profiles in human gastric cancer: expression of maspin correlates with lymph node metastasis.

To seek for a candidate gene that would regulate tumour progression and metastasis in gastric cancer, we investigated gene expression profiles by using DNA microarray. Tumour tissue and adjacent normal tissue were obtained from 21 patients with gastric cancer and then examined for their gene expression profiles by the Gene Chip Human U95Av2 array, which includes 12 000 human genes and EST sequences. A total of 25 genes were upregulated and two genes were downregulated by at least four-fold in the tumour tissue. In a further analysis according to lymph node metastasis, the expressed levels of maspin, as well as carcinoembryonic antigen and nonspecific crossreacting antigen were significantly higher in tumours with lymph node metastasis than in those without it. Maspin expression in 85 gastric cancer patients was further investigated by using immunohistochemistry. Maspin expression was not observed in normal gastric epithelia without intestinal metaplasia. In contrast, maspin was expressed in 74 of 85 tumour tissues. There was a significant correlation between the incidence of maspin-positive tumour staining and lymph node metastasis. These results suggest that maspin has a potential role for tumour metastasis in gastric cancer.

Adult↗

PubMed2005

Therapy-related myelodysplastic syndrome in childhood: a retrospective study of 36 patients in Japan.

We report here a retrospective analysis of 36 children with therapy-related myelodysplastic syndrome (t-MDS) diagnosed between 1990 and 1999 in Japan. Their median age was 7.7 years and the median latency period for the development of t-MDS was 38.5 months. The primary tumors were hematologic in 15 of the cases and nonhematologic in 21. Chromosomal abnormalities were detected in 32/34(94%) patients: abnormalities of chromosomes 5and/or 7 in 41% and notably, 11q23 abnormalities in 31%. The prognosis of children with t-MDS was very poor as compared to children with primary MDS (5 year survival: 16% versus 54%, p<0.0001).

Adolescent↗

PubMed2005

Effects of noninherited maternal antigens on allotransplant rejection in a transgenic mouse model.

We studied the influence of noninherited maternal antigen (NIMA) on allotransplant rejection using a mouse transgenic model. CBK transgenic (CBA [H-2k] expressing K(b) MHC class I transgene) mice were used as donors in heart transplantation experiments. Offspring of BM3.3 (CBA anti-K(b) TCR transgenic) male mice and (CBA x CBK)F1 females were used as NIMA (offspring that did not inherit K(b)) and IMA (offspring that inherited K(b) maternal antigen) recipient mice. Survival of allografts was monitored and the alloimmune response evaluated using an ELISPOT assay. IMA mice accepted CBK heart allografts and displayed no alloresponse to K(b+) cells. In contrast, mice never exposed to K(b) (offspring of BM3.3 males and CBA females) acutely rejected their grafts within 18 days posttransplantation and exhibited potent inflammatory alloresponses to K(b+) cells. NIMA mice displayed prolonged survival of allotransplants (MST >60 days). Although no deletion of anti-K(b) TCR transgenic cells was detected in these mice, they had a marked reduction in the frequency of activated alloreactive T cells producing type 1 (IFN-gamma and IL-2) cytokines and concomitant expansion of type 2 (IL-4) cytokine-secreting cells. Finally, depletion of CD4+ T cells from NIMA mice restored acute rejection of CBK hearts. This study is the first demonstration of the tolerogenic effects of NIMA on alloimmunity and allotransplant rejection in a transgenic model. It is shown that, although the NIMA tolerogenic effect is not due to deletion of alloreactive T cells, it is mediated by CD4+ T cells producing type 2 cytokines.

Animal Nutritional Physiological Phenomena↗

PubMed2005

[Surgery for the thymoma combined with pure red cell aplasia and myasthenia gravis].

UNLABELLED: Pure red cell aplasia (PRCA) and myasthenia gravis (MG) are respectively combined with thymoma, however, these 3 complications are extremely rare coexisted as a clinical triad. A 73-year-old female with mediastinal tumor found in 2000 was pointed out anemia in June 2002. As PRCA was diagnosed by the bone marrow examination, blood transfusion had been performed. By a chest computed tomography (CT), a thymoma in size of 7 x 5 cm in diameter was recognized in the anterior mediastinum. The serum level of anti-acetylcholine receptor antibody was elevated to be 35 nmol/l. MG was simultaneously diagnosed with a decreased power of neck muscle. The extended thymectomy was performed in August 2002, and pathological diagnosis disclosed a 'type AB' by World Health Organization (WHO) classification. After the operation, the decreased power of neck muscle had been improved, however, PRCA had not been remitted in the early-postoperative term. Blood transfusion had been required (2-4 units/1-2 weeks) for the postoperative 7 months' term. A cyclosporin (250 mg/day) as an adjuvant therapy was administered in April 2003. One month later, the patient's serum level of Hb had been over 10 g/dl without blood transfusion. The patient has been followed up with reducing the dose of cyclosporin. CONCLUSIONS: Surgery for a thymoma combined with PRCA and MG was effective for MG but not for PRCA in an early-postoperative term, however, a multimodality therapy with immunosuppressant as a postoperative adjuvant should bring a favorable outcome to patient's clinical data, and the postoperative long-observation must be critical in this case.

Aged↗

PubMed2004

Effects of vitamin K2 (menatetrenone) and alendronate on bone mineral density and bone strength in rats fed a low-magnesium diet.

In this study, we examined changes in bone parameters and bone strength in rats fed low-Mg diets (experiment 1) and the effects of vitamin K2 (MK-4, experiment 3) and alendronate (ALN, experiment 2) in this model. In experiment 1, 5-week-old male Wistar rats were fed three low-Mg diets (Mg 9, 6, 3 mg/100 g diet) for 4 weeks. Although the cortical bone mineral content (CtBMC) and cortical thickness (CtTh) of the femoral diaphysis in all low-Mg-diet groups were the same as or greater than those in the intact group (Mg: 90 mg/100 g diet), the maximum load and elastic modulus were significantly reduced in the 3-mg-Mg group. In experiment 2, 4-week-old Wistar rats were fed a 6-mg-Mg diet for 8 weeks, and the effect of ALN (2, 20, and 200 microg/kg twice a week) was evaluated. The administration of ALN at 200 microg/kg increased the cortical bone mineral content (CtBMC), CtTh, and maximum load, but had no effect on the elastic modulus, as compared with the low-Mg-control group. In experiment 3, the effect of MK-4 was evaluated under the same conditions as in experiment 2. The administration of MK-4 had no effect on CtBMC, CtTh, or bone components of the femoral diaphysis. However, MK-4 inhibited the decreases in maximum load and elastic modulus due to the low-Mg diet. Since there is no other experimental model in which there is a decrease in bone mechanical properties without a decrease in bone mineral content, the low-Mg diet model is considered to be an excellent model for examining bone quality. Our results from this model suggest that MK-4 and ALN affect bone mechanical properties by different mechanisms.

Alendronate↗

PubMed2004

Histochemical evaluation for the biological effect of menatetrenone on metaphyseal trabeculae of ovariectomized rats.

To evaluate the biological effects of vitamin K2 (menatetrenone, MK-4) on ovariectomy (OVX)-induced bone loss, we have examined histological alterations of femoral metaphyses of sham-operated (sham group), ovariectomized (OVX group), and MK-4 dietary-supplemented OVX (MK-4 group; 50 mg/kg per day) female Fischer rats 1, 2, 5, and 8 weeks after OVX. In the first week, rats of the OVX and MK-4 groups showed discontinuous trabeculae compared with sham-operated rats. At 2 weeks after OVX, the OVX rats revealed many large tartrate resistant acid phosphatase (TRAP)-positive osteoclasts, while osteoclasts in the MK-4-treated rats were similar in size to those of the sham group. At 5 weeks, the OVX and MK-4 groups revealed fragmented trabeculae in femoral metaphyses. The cartilage matrix was partially exposed due to stimulated bone resorption in the OVX group, but not in the MK-4 group. After 8 weeks, the OVX rats had little metaphyseal trabeculae, whereas the MK-4-treated rats had maintained short trabeculae. Despite the presence of intense alkaline phosphatase-positive osteoblasts on trabeculae in the MK-4 group, TRAP-positive osteoclasts were flattened without developing ruffled borders. Therefore, MK-4 appeared to lessen the increase in osteoclastic bone resorption induced by OVX, as well as to maintain the accelerated osteoblastic activity. It is of importance to identify the target cells for MK-4 in bone. Autoradiography localized [3H]-labeled MK-4 mainly in osteoblasts and adjacent bone matrices, but not in osteoclasts, indicating that MK-4 targets osteoblasts. Thus, MK-4 appears to target osteoblasts, consequently inhibiting bone loss induced by ovariectomy.

Animals↗

PubMed2004

PDX1 homeobox protein expression in pseudopyloric glands and gastric carcinomas.

BACKGROUND AND AIMS: Although it has been reported that intestinal metaplasia implicated in gastric carcinogenesis is induced by the ParaHox gene CDX2, it is unclear which genes are responsible for the formation of pseudopyloric glands and whether they play a role in gastric carcinogenesis. Pancreatic-duodenal homeobox 1 (PDX1) is also a ParaHox gene which contributes to the genesis and development of the pancreas, duodenum, and antrum. To clarify its significance for the formation of pseudopyloric glands and gastric carcinogenesis, we investigated expression of PDX1 and mucin in gastric carcinomas and surrounding mucosa. METHODS: Gastric carcinoma tissues from 95 patients were used for immunohistochemical analyses of PDX1, and mucins MUC6 and MUC5AC. RESULTS: PDX1 was found to be frequently expressed in pseudopyloric glands and intestinal metaplasia. MUC6 was more abundant than MUC5AC in pseudopyloric glands while higher levels of MUC5AC than MUC6 were evident in intestinal metaplasia. The frequency of PDX1 positive reactivity was higher in differentiated type carcinomas (39/43, 90.7%) and T1 carcinomas (42/43, 97.7%) than in undifferentiated type (33/52, 63.5%) and T2-4 (30/52, 57.7%) carcinomas. PDX1 and MUC6 double positive expression was observed in carcinomas, respectively, including the corpus, and also correlated with histological type and depth of invasion. In contrast, no link was apparent between PDX1 and MUC5AC double positive reactivity and histological type. CONCLUSION: Our study suggests that PDX1 plays an important role in the development of pseudopyloric glands, and that pseudopyloric glands may reflect a condition associated with gastric carcinogenesis.

Aged↗

PubMed2003

In vitro effects of combinations of cis-amminedichloro (2-methylpyridine) platinum (II) (ZD0473) with other novel anticancer drugs on the growth of SBC-3, a human small cell lung cancer cell line.

Among numerous clinical regimens of combination chemotherapy, synergy has been observed to be particularly marked with combinations containing cisplatin (CDDP). However, the clinical use of CDDP has sometimes been limited by acquired resistance. The new-generation platinum drug, ZD0473, was synthesized with the aim of hindering the reaction of the drug with thiols, by the introduction of a 2-methylpyridine ligand. This enables the drug to exert antitumor activity against cisplatin-resistant cancer cells with elevated glutathione and/or metallothionein levels. The drug was also shown experimentally to overcome cisplatin resistance due to impaired drug accumulation, and enhanced DNA repair/tolerance to platinum-DNA adducts. We investigated the effects of combinations of ZD0473 with other anticancer drugs on the growth of a human small-cell lung cancer cell line (SBC-3). Six novel anticancer drugs were tested: docetaxel (TXT), paclitaxel (TXL), vinorelbine (VNB), irinotecan (CPT-11), gemcitabine (GEM) and pemetrexed (MTA). The growth inhibitory effect of the drugs was measured by MTT assay and the effects of the combination regimens were evaluated by the combination index analysis method developed by Chou and Talalay. Synergy was demonstrated for the combination regimens of ZD0473-GEM and ZD0473-TXL, while an additive effect was observed with combinations containing TXT, VNB, CPT-11 or MTA. In the case of the ZD0473-GEM combination, synergy was observed over a wide range of inhibition levels at dose ratios of 50:1, 100:1 and 250:1. The level of synergy was equivalent to that observed for combinations of CDDP-etoposide, CDDP-GEM and nedaplatin-CPT-11. The results suggest that the combination of ZD0473 with GEM merits further investigation in small cell lung cancer.

Antimetabolites, Antineoplastic↗

PubMed2002