Exogenous cells

For example, Jurkat T cells apoptose in response to serum withdrawal, addition of exogenous cell-permeable ceramide or stimulation with the apoptotic agonist Fas. However, transfection with SPHKl, measured as a 400-600-fold increase in activity, reduced apoptosis and inaeased proliferation (Ohvera et al, 1999). These effects were correlated with an inhibition of the activity of caspase 3, an initiator caspase (Olivera et al, 1999), A similar effect has recently been observed in rat pheochromocytoma PC12 cells (Edsall etal, 2(X)1). Tropbic withdrawal led to the activation of... 

The second approach involves the injection of isolated exogenous cells. For example, pluripotent stem cells have been injected into the circulatory system or directly into the heart. Furthermore, embryonic stem cells, skeletal myoblasts, skeletal muscle-derived multimyogenic stem cells, unselected bone marrow stem ceUs, mesenchymal stem cells, endothelial precursor cells, " and adult cardiac stem cells have been shown to differentiate into cardiac phenotypes. Though improved cardiac function has been reported, the underlying mechanism is not clear and the survival rates of the cells tend to be extremely low. This is probably due to the lack of local support for the cells to grow and establish themselves. 

Microbiological procedures which exploit the ability of bacteria and photosynthetic algae to incorporate exogenous labeled precursors such as 14CO2, SO%, and 32pQ3- [ can be used to label complex molecules in cells such as proteins (qv) and nucleic acids (qv), which are then processed to give labeled constituents such as uniformly labeled C-amino acids, C-nucleotides, C-fipids, LS-amino acids, etc (8). 

Modulation of the Killing of Mammalian Cells by Thiols. Important aspects of the effects of exogenous thiols on clonogenic cell survival following exposure to low linear energy transfer (LET) radiations include the following. 

Increasing endogenous CO production or directly applying exogenous CO has not been tested on humans. Ample experimental data, however, have been obtained in different animal species and from various types of cultured cells, supporting the idea of using CO as an effective therapeutic agent. 

There are endogenous and exogenous plasminogen activators. Endothelial cells (andtumor cells) synthesize... 

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