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Satoshi Nagayama

Publications and source records attributed to Satoshi Nagayama.

23 records · Page 2Linked to original sources
PubMedDate not supplied

How to control blood glucose under continuous glucose challenge.

A newly improved method for controlling blood glucose was compared with the standard model predictive controller under continuous glucose infusion. Continuous intravenous glucose infusion at rates of 50 or 100 mg/kg/hour was conducted on pancreatectomized dogs. An improved blood glucose control method using a combination of the proportional controller in the initial stage and the model predictive controller in the later stage was compared with the simple model predictive controller. The parameters of the controller were determined by identifying individual responses to the infused insulin during the first 60 minutes. The parameters of the proportional controller were changed at 60, 90, and 120 minutes to reflect the response to the infused insulin. The simple model predictive controller was able to reach the target level in the usual manner under the low infusion rate of glucose. However, under glucose infusion rates of 100 mg/kg/hour and more, it was difficult to reach the target level within 8 hours. In contrast, the improved system could reach the target level within 5 to 8 hours even under continuous glucose challenge. Addition of the modified proportional controller to the model predictive controller can stabilize the blood glucose control even under continuous glucose infusion.

Animals↗
PubMedDate not supplied

Altered expression of the receptor and ligand in the TGF beta signaling pathway in diffusely infiltrating colon carcinoma.

A diffusely infiltrating colorectal carcinoma (DICC) is a distinct clinicopathological entity demonstrating invasive growth with extensive matrix production and associated with an extremely poor prognosis. The factors producing these peculiar features, however, remain to be determined. Here we investigated the receptor and ligand of the transforming growth factor (TGF) beta signaling pathway in 32 DICCs and 60 common type colorectal carcinomas (CCCs). Immunohistochemical analysis revealed that the expression of TGF beta 1 was markedly increased in DICC, especially of the schirrous type, compared to CCC, whereas the expression of the TGF beta type II receptor (RII) was significantly decreased in DICC compared to CCC. The molecular basis for the reduced expression of RII was further investigated in 15 cases of DICC with a diminished RII expression. Two somatic mutations were found: one was a missense mutation in the kinase domain (Cys533Tyr), and the other was a G to C transition at the putative Sp1 binding site in the core promoter region. The latter mutation reduced the promoter activity, which may be due to a reduced affinity of the mutant sequence to the putative transcriptional regulator, which was neither Sp1 nor Sp3. No methylated cytosine was found at any CpG sites in the promoter region. These results suggested the presence of unidentified mechanisms for the diminished expression of RII in DICC cases.

Colonic Neoplasms↗
PubMedDate not supplied

Tumour plasticity and extravascular circulation in ECV304 human bladder carcinoma cells.

BACKGROUND: The concepts of vasculogenic mimicry and mosaic vessels have been proposed as novel modes of tumour neovascularisation. However, the presence and significance of these types of neovascularisation remain unclear. MATERIALS AND METHODS: ECV304 human bladder carcinoma cells were used to determine how tumour cells take part in tumour neovascularisation. RESULTS: Subcutaneous ECV304 xenografts in mice showed various vessel types, including angiogenic vessels, tumour cell-related vessels and extracellular matrix networks. A tracer experiment demonstrated perfusion of beads in these structures. ECV304 cells, cultured on collagen I gels, formed tube networks with expressions of several endothelial-related markers. In coculture models of ECV304 cells and human umbilical vein endothelial cells, the two cells collaborated to form sprouts or networks. CONCLUSION: ECV304 cells possess an endothelial character which confers the ability to mimic and collaborate with vascular endothelial cells and facilitates the acquisition of tumour microcirculation.

Animals↗