This paper is published under the responsibility of the Secretary-General of the OECD. The opinions expressed and the arguments employed herein do not necessarily reflect the official views of OECD countries. The publication of this document has been authorised by Ken Ash, Director of the Trade and Agriculture Directorate. This paper and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area. The statistical data for Israel are supplied by and under the responsibility of the relevant Israeli authorities. The use of such data by the OECD is without prejudice to the status of the Golan Heights, East Jerusalem and Israeli settlements in the West Bank under the terms of international law.
Land fragmentation, in which a farm operates multiple, separate plots of land, is a common phenomenon in Japan and many other countries. Usually, land fragmentation is regarded as a harmful phenomenon as it increases production costs and reduces the advantages of scale economies. However, it is also known that fragmentation may have beneficial effects in reducing risk through spatial dispersion of plots. Thus, land fragmentation has both costs and benefits, and whether it is beneficial or harmful is determined by the magnitude of these costs and benefits. This article investigates the costs and benefits of land fragmentation empirically using panel data from Japanese rice farms. The empirical results reveal that fragmentation increases production costs and offsets economies of size, and these impacts strengthen as farm size increases. Moreover, although fragmentation does reduce production risk, its monetary value is far below the cost of land fragmentation. From these findings, we conclude that land fragmentation is an impediment to efficient rice production in Japan.
Cancer immunotherapy by dendritic cell (DC)/tumor cell fusion hybrids (DC/TC hybrids) has been shown to elicit potent anti-tumor effects via the induction of immune responses against multiple tumor-associated antigens. In the present study, we compared the anti-tumor effects of vaccinating Balb/c mice (H-2(d)) with CT26CL25 colon carcinoma cells that had been fused with either syngeneic DCs from Balb/c mice, allogeneic DCs from C57BL/6 mice (H-2(b)) or semiallogeneic DCs from B6D2F1 mice (H-2(b/d)). Preimmunization with either semiallogeneic or allogeneic DC/TC hybrids induced complete protection from tumor challenge, whereas mice preimmunized with syngeneic DC/TC hybrids were only partially protected (75% tumor rejection). The average number of pulmonary metastases after intravenous tumor injection decreased significantly following immunization with semiallogeneic or allogeneic DC/TC hybrids (8.3 +/- 7.9 or 16.3 +/- 3.5, mean +/- SD) relative to syngeneic DC/TC hybrids (67.8 +/- 6.3). These data demonstrate that vaccination with semiallogeneic DC/TC hybrids resulted in the greatest anti-tumor efficacy. Anti-tumor effects showed by in vivo studies were virtually accomplished by the frequency of induced CTLs specific to both gp70 and beta-galactosidase assessed by using pentameric assay. Among the fusion vaccines tested, semiallogeneic DC/TC hybrids induced the highest ratio of Th1 cytokine IFN-gamma to Th2 cytokine IL-10. In addition, allogeneic or semiallogeneic DC/TC hybrids elicited a significantly stronger NK activity than syngeneic DC/TC hybrids. These findings suggest that in clinical settings, DCs derived from a healthy donor (which are generally characterized as more semiallogeneic than allogeneic) may be more capable than autologous DCs of inducing promising anti-tumor effects in vaccinations with DC/TC hybrids.
hepatic metastasis in their resected liver have shown recurIt is well known that a urokinase-type plasminogen rence within 3 years, 9 prompting us to seek a new predictor activator receptor (uPAR) is a key protein in the plasfor this recurrence. minogen activation system, which plays a proteolyti-The metastatic process in malignant tumors involves local cally important role in the invasion and metastasis of invasion, intravasation, and extravasation. 10 These events various cancer cells. To assess the expression of uPAR depend on the tumor-associated proteolytic process including in hepatocellular carcinoma (HCC), we analyzed the exthe plasminogen activation system, and many reports have pression of uPAR messenger RNA (mRNA) and the proshown that the urokinase-type plasminogen activator (uPA) tein in 31 pair-samples of solitary HCC and nontumorous plays an important role in this process. 11-13 uPA is released liver tissues from the same patients. Fifteen samples exfrom tumor and stromal cells [14][15][16] in a single-chain zymogen hibited no histological potential of recurrence, such as form, pro-uPA. 17,18 pro-uPA is converted into a two-chain acportal involvement or intrahepatic metastasis (group A), tive form of uPA, which converts the ubiquitous zymogen and 16 samples exhibited such histological features plasminogen into the proteolytically active form, plasmin. (group B). Seventy-one percent of the cases showedPlasmin by itself degrades the extracellular matrix and actiuPAR signals, and these signals were mainly localized vates collagenases. 19 Some authors have described that poor at the cytoplasm of the tumor cells and tended to be at prognostic types of cancer cells show high levels of uPA. 20-22the front of invasive foci. 87.5% of the cases in group B The mechanism of the initial activation of pro-uPA under showed uPAR signals against 53.3% of the cases in group physiological conditions is unknown. uPA has a specific re-A (P õ .05). The rate of recurrence in the uPAR positive/ ceptor (uPAR) anchoring to the cell surface by glycosyl-phonegative cases in group A was 75.0% and 14.3%, respecphatidyl-inositol. [23][24][25][26][27] uPAR is a protein with an Mr55000-tively (P õ .05). In non-neoplastic cases, e.g., chronic ac-60000 (55-60 Kd molecular weight of uPAR antigen), tive hepatitis and cirrhosis, weak uPAR mRNA and protranslated from a 1.4-kb messenger RNA (mRNA) 28 and its tein signals were detected in hepatocytes neighboring amino-terminal domain has a high affinity with an epidermal the portal tracts, suggesting that this protein plays some growth factor-like domain in the pro-uPA and uPA molerole in such cases. The present study indicates that cules. 29,30 uPAR synthesis is regulated by growth factors such uPAR plays an important role at least in its initial stage as transforming growth factors b 1 and b 2 , epidermal growth in invasion and metastasis of HCC, and that uPAR exfactor, 31,32 and phorbol 12-myristate 13-acetate. 33 Binding of pression can be a candidate predictor of these factors.pro...
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