Biomedical subjects

Yuji Yamada

Publications and source records attributed to Yuji Yamada.

58 records · Page 4Linked to original sources

PubMed2002

Antiangiogenic effect by SU5416 is partly attributable to inhibition of Flt-1 receptor signaling.

Interaction between vascular endothelial growth factor (VEGF) and its cognate receptors, KDR/Flk-1 and Flt-1, of vascular endothelial cells is expected to induce an angiogenesis "switch" in tumors and other angiogenesis-associated diseases. SU5416, a selective inhibitor of the KDR/Flk-1 tyrosine kinase, is known to be a potent inhibitor of tumor angiogenesis. In this study, we first observed that SU5416 inhibited Flt-1 tyrosine kinase activity at similar doses, in addition to inhibiting KDR/Flk-1 tyrosine kinase activity in response to VEGF. SU5416 inhibited cell migration of human vascular endothelial cells expressing both Flt-1 and KDR in response to VEGF and also inhibited the cell migration in response to placenta growth factor (PIGF), a specific ligand for Flt-1. Chemotaxis of monocytes expressing only Flt-1 was also inhibited by SU5416 in a dose-dependent manner. Moreover, SU5416 was found to inhibit tyrosine kinase of Flt-1 in response to PIGF in vitro. And angiogenesis induced by PIGF in a Matrigel plug assay was inhibited by administration of SU5416. The antiangiogenic effects by this VEGF receptor-targeting compound appeared to be mediated through interference not only with KDR/Flk-1 but also with Flt-1. Cell migration of vascular endothelial cells and monocytic cells through Flt-1, thus, might play a key role in VEGF-induced tumor angiogenesis in concert with KDR/Flk-1.

3T3 Cells↗

PubMedDate not supplied

CyberKnife stereotactic irradiation for metastatic brain tumors.

BACKGROUND: The CyberKnife provides a new technique for performing frameless stereotactic irradiation. So far, few reports have been published on clinical outcomes obtained with the CyberKnife. This report summarizes our clinical experience with CyberKnife irradiation for metastatic brain tumors. MATERIALS AND METHODS: Seventy-seven lesions (48 patients) were evaluated and analyzed, and 66 lesions in 41 patients were treated with stereotactic radiosurgery (SRS). The prescribed dose was 9 to 30 Gy. RESULTS: Freedom from progression of the tumors was more likely with a prescribed dose of at least 24 Gy than with one of less than 20 Gy (p=0.0244; log-rank test). The CR (complete response) rate was significantly higher when D99 was at least 24 Gy (p=0.0045). There were no severe side effects. CONCLUSION: Stereotactic irradiation with the CyberKnife for metastatic brain tumors is effective and safe. D99 should be at least 24 Gy for CyberKnife SRS treatment.

Brain Neoplasms↗

PubMedDate not supplied

Long-term cryopreservation of peripheral blood stem cells in patients with advanced germ cell tumors using the dump-freezing method at -80 degrees C.

The objectives of this study were to evaluate the hematopoietic activity of peripheral blood stem cells (PBSCs) harvested from patients with advanced germ cell tumors after long-term cryopreservation in a mechanical freezer at -80 degrees C. Forty-one patients with advanced tumors were enrolled in this study. Flow cytometric analysis was performed to determine the total cell viability and the viability of CD34 positive cells of PBSCs stored between January 1995 and December 2001. The 41 patients were divided into two groups according to the duration of cryopreservation. In the 21 patients in whom the duration of storage was greater than 5 years, the total cell number did not change significantly before and after long-term cryopreservation (p=0.75). The percentage of viable cells and the total number of viable cells was significantly decreased after long-term cryopreservation (p<0.001 and p<0.05, respectively). However, the percentage of CD34 positive cells was significantly increased to 2.34% from 1.85% (p<0.05), resulting in non-statistically significant change in the total viable CD34 positive cells (p=0.98). A similar relation was found in the 20 patients whose storage duration was less than 2 years, although a significant change was found only in the percentage of viable cells. Moreover, pre-PBSCH factors, including age, cumulative dosage of cisplatin and the International Germ Cell Cancer Collaborative Group classification at the diagnosis did not affect the viable CD34 positive cell count after long-term cryopreservation. In conclusion, the present results suggest that CD34 positive cells could be successfully cryopreserved in a mechanical freezer at -80 degrees C for more than 5 years with no relation to pre-PBSCH factors and efficacy of PBSCH itself.

Adolescent↗

PubMedDate not supplied

Quantitative evaluation of changes in irradiated lung fields after stereotactic irradiation by the Polygon Method.

PURPOSE: To evaluate areas of change in lung after thoracic stereotactic irradiation (STI). MATERIALS AND METHODS: We developed a method of evaluation named the Polygon Method, to measure the irradiated lung fields of 12 lung tumors treated by STI. Before treatment, each targeted field was divided into several circular zones of 2 cm in width centered at the tumor on high resolution computed tomography, and the areas of each zone before and after treatment were compared. RESULTS: Six months after treatment, the areas of the zone within 2 cm from the tumor decreased, and the mean ratio of areas after and before STI was 0.849 (range, 0.515 to 1.052, p=0.0254). By contrast, the areas of zones located at 4 to 6, 6 to 8, 8 to 10, and more than 10 cm from the tumor tended to increase, with mean ratios of 1.059, 1.058, 1.089 (p=0.0374), and 1.084, respectively. CONCLUSION: After thoracic STI, volume loss in the lung is limited to the field in close proximity to the tumor, while compensatory expansion of the lung occurs in fields distant from the tumor.

Adenocarcinoma↗