Hypoxia contributes to encapsulated pancreatic islet graft failure. To gain insight into the mechanisms that lead to hypoxia-induced graft failure, encapsulated islet function, vitality, and cell replication were assessed after 2 and 5 days of hypoxic (1% O 2 ) and normoxic (20% O 2 ) culture. The mRNA expression levels of Bcl-2, Bax, inducible nitric oxide synthase (iNOS), and monocyte chemoattractant protein 1 (MCP-1) were assessed, as well as the amount of nitrite and MCP-1 in the culture medium. Hypoxia was associated with loss of encapsulated islet function and vitality, but not with an increase in islet cell replication. Loss of vitality was due to necrosis, and only modestly due to apoptosis. Hypoxia was not associated with changes in the Bcl-2/Bax mRNA ratio, but it did increase the expression of iNOS and MCP-1 mRNA. The increased mRNA levels were, however, not associated with elevated concentrations of nitrite nor with elevated levels of MCP-1 protein. The increased iNOS mRNA levels imply a role for NO in the completion of cell death by hypoxia. The increased MCP-1 mRNA levels suggest that encapsulated islets in vivo contribute to their own graft failure by attracting cytokine-producing macrophages. The discrepancy between iNOS mRNA and nitrite is explained by the longer half-life of NO during hypoxia. MCP-1 protein levels are underestimated as a consequence of the lower number of vital cells in combination with a higher proteolytic activity due to necrosis. Thus, strategies to eliminate hypoxia may not only improve islet function and vitality, but may also reduce the attraction of macrophages by encapsulated islets. INTRODUCTIONthis end, islet function, islet vitality, and islet cell replication rates of encapsulated islets were assessed during Microencapsulation of pancreatic islets may avoid the normoxic and hypoxic culture. In relation to islet vitalneed for permanent immunosuppressive drug therapy and ity, apoptosis was also studied by measuring the expresopen the perspective of xenotransplantation in the treatsion of the antiapoptotic gene Bcl-2 and the proapoptotic ment of insulin-dependent diabetes mellitus. The comgene Bax. Bcl-2 is a known inhibitor of hypoxia-induced monly applied alginate poly-L-lysine alginate microcapcell death (31-33). To determine whether hypoxia-induced sules provide protection against antibodies and immune cell death was mediated through nitric oxide (NO) (18, cells, while allowing diffusion of insulin and glucose across 31), the expression of inducible nitric oxide synthase the capsule membrane. Inherent to the use of immuno-(iNOS) gene and nitrite formation as a measure of NO protective capsules is that revascularization of the islets production were measured during culture. The effect of of Langerhans cannot occur. Absence of blood supply hypoxia on the expression of monocyte chemoattractant causes attrition and hypoxia, which will lead to metaprotein 1 (MCP-1), a factor that may contribute to graft bolic exhaustion and cell death. This explains why, in failure by ...

The hybrid-QA method is adequate for efficient and accurate 3D dose verification. It combines time efficiency of model-based QA with reliability of measurement-based QA and is suitable for implementation within any radiotherapy department.

The human pancarcinoma-associated epithelial glycoprotein-2 (EGP-2), also known as 17-1A or Ep-CAM, is a 38-kDa transmembrane antigen, commonly used for targeted immunotherapy of carcinomas. Although strongly expressed by most carcinomas, EGP-2 is also expressed in most simple epithelia. To evaluate treatment-associated effects and side-effects on tumor and normal tissue respectively, we generated an EGP-2-expressing transgenic Wistar rat. To express the cDNA of the EGP-2 in an epithelium-specific manner, the 5' and 3' distal flanking regions of the human keratin 18 (K18) gene were used. EGP-2 protein expression was observed in the liver and pancreas, whereas EGP-2 mRNA could also be detected in lung, intestine, stomach and kidney tissues. In this rat, EGP-2-positive tumors can be induced by injecting a rat-derived carcinoma cell line transfected with the GA733-2 cDNA encoding EGP-2. Transgenic rats were used to study specific in vivo localization of an i.v. anti-EGP-2 monoclonal antibody, MOC31, applied i.v. Immunohistochemical analyses showed the specific localization of MOC31 in s.c. induced EGP-2-positive tumors, as well as in the liver. In contrast, in EGP-2-transgenic rats, MOC31 did not bind to EGP-2-negative tumors, the pancreas, or other normal tissues in vivo. In conclusion, an EGP-2-transgenic rat model has been generated that serves as a model to evaluate the efficacy and safety of a variety of anti-EGP-2-based immunotherapeutic modalities.

These findings argue against a role of STAT3beta as a negative regulator of G-CSF-induced expression of p27 and myeloid differentiation.