Neoplastic transformation of porcine mammary epithelial cells in vitro and tumor formation in vivo.

BackgroundThe mammary glands of pigs share many functional and morphological similarities with the breasts of humans, raising the potential of their utility for research into the mechanisms underlying normal mammary function and breast carcinogenesis. Here we sought to establish a model for the efficient manipulation and transformation of porcine mammary epithelial cells (pMEC) in vitro and tumor growth in vivo.MethodsWe utilized a vector encoding the red florescent protein tdTomato to transduce populations of pMEC from Yorkshire -Hampshire crossbred female pigs in vitro and in vivo. Populations of primary pMEC were then separated by FACS using markers to distinguish epithelial cells (CD140a-) from stromal cells (CD140a+), with or without further enrichment for basal and luminal progenitor cells (CD49f+). These separated pMEC populations were transduced by lentivirus encoding murine polyomavirus T antigens (Tag) and tdTomato and engrafted to orthotopic or ectopic sites in immunodeficient NOD.Cg-Prkdc (scid) Il2rg (tm1Wjl) /SzJ (NSG) mice.ResultsWe demonstrated that lentivirus effectively transduces pMEC in vitro and in vivo. We further established that lentivirus can be used for oncogenic-transformation of pMEC ex vivo for generating mammary tumors in vivo. Oncogenic transformation was confirmed in vitro by anchorage-independent growth, increased cell proliferation, and expression of CDKN2A, cyclin A2 and p53 alongside decreased phosphorylation of Rb. Moreover, Tag-transformed CD140a- and CD140a-CD49f + pMECs developed site-specific tumors of differing histopathologies in vivo.ConclusionsHerein we establish a model for the transduction and oncogenic transformation of pMEC. This is the first report describing a porcine model of mammary epithelial cell tumorigenesis that can be applied to the study of human breast cancers

Immiserizing growth and the Metzler Paradox in the Ricardian Model

Conditions for the occurrence of immiserizing growth and the Metzler paradox are analysed in the Ricardian model when consumers in the foreign country have Leontief preferences while consumers in the home country have Cobb-Douglas preferences. By using specific functional forms, the conditions for the occurrence of the two paradoxes are defined in terms of the exogenous parameters of the model rather than endogenous variables such as the elasticity of demand for exports in the conditions of Bhagwati (1958) and Metzler (1949a and b). It is shown that the simultaneous occurrence of both paradoxical results is possible for some parameter values

Multilateral trade liberalisation, foreign direct investment and the volume of world trade

A paradox in international trade is that multilateral trade liberalisation has resulted in increases in both the volume of world trade and the amount of foreign direct investment (FDI). This note presents a Cournot duopoly model with two regions, each consisting of two countries, and with an inter-regional transport cost. It is shown that multilateral trade liberalisation may lead firms to switch from exporting to undertaking export-platform FDI when the interregional transport cost is high. Also, when the inter-regional transport cost is high, the switch to FDI leads to an increase in the volume of world trade in this industry

The optimality of optimal punishments in Cournot supergames

The result of Colombo and Labrecciosa (2006) that optimal punishments are inferior to Nash-reversion trigger strategies with decreasing marginal costs is due to the output when a firm deviates from the punishment path being allowed to become negative

Tool-free, Cosmetically Hidden Phone Display and Back Cover Disassembly Port

The back cover and/or display displays of many portable devices such as smartphones and tablets are often integrated with the main assembly. If the back cover assembly or the phone display needs to be removed (e.g., to access the battery) or needs to be replaced, the device owner needs to approach a service center for such work since specialized tools are often required for removal. This disclosure describes a mechanism for easy removal of back cover or display of a device without impacting aesthetics of the device. Per the techniques of this disclosure, a slot is machined or molded on the adhesive landing between the display/ back cover and the SIM tray opening. The slot can be accessed easily with the SIM tray tool or a paperclip