Cell-type selectivity

The vitamin D receptor (VDR/NR1I1) is a member of the superfamily of steroid hormone receptors. It regulates calcium homeostasis, cell proliferation, and differentiation, and exerts immunomodulatory and antimicrobial functions [119]. VDR binds to and mediates the calcemic effects of calcitriol (la,25-dihydroxy vitamin D3) after forming an heterodimer with RXR. la,25-dihydroxyvitamin D3 negatively regulates its own synthesis by repressing the 25-hydroxyvitamin D3 la-hydroxylase (CYP27B1) in a cell-type selective event that involves different combinations of multiple VDR response elements [120, 121]. 

Gross, S. S., Stuehr, D. J., Aisaka, K., Jaffe, E. A., Levi, R., and Griffith, O. W. (1990). Macrophage end endothelial cell nitric oxide synthesis Cell-type selective inhibition by N -arainoarginine, N -nitroarginine and N -methylarginine. Biochem. Biophys. Res. Commun. 170, 96-103. 

It is clear from the literature review that the need continues to exist for a high throughput functional toxin detection system, which could detect and identify unknown or unexpected toxic chemicals in continuous long term experiments in field conditions. Microelectrode array recordings may show some promise in some specific fields as they are relatively more rugged, simpler and cheaper to implement than automated patch clamp devices. However, in addition to international validation studies, cell type selection and automated data analysis capabilities of multiple signals will be critical. 

Cancer cell type Normal cell type Selectivity Cancer cell viability Normal cell viability Plasma type Ret. 

Because different cell types in eukaryotic organisms express selected subsets of genes, RNA preparations from cells or tissues in which genes of interest are selectively transcribed are enriched for the desired mRNAs. cDNA... 

Eflornithine (difluoromethylornithine, DFMO) inhibits the ornithine decarboxylase of the polyamine pathway, in both the trypanosome and the mammalian cell, by acting as an irreversible competitor of the natural substrate ornithine. Inhibition of ornithine decarboxylase results in depletion of the polyamines, putrescine, spermidine and spermine, which are essential for cell proliferation. Eflornithine selectively harms the parasite and not the mammalian cells, despite acting as an ornithine decarboxylase inhibitor in both cell types. This selectivity is explained by the lower rate of ornithine decarboxylase production in the parasite, as compared to mammalian cells. Due to the high turnover rate, mammalian cells are capable of quickly replenishing inhibited ornithine decarboxylase by newly... 

Tubulins arose very early during the course of evolution of unicellular eukaryotes and provide the machinery for the equipartitioning of chromosomes in mitosis, cell locomotion, and the maintenance of cell shape. The primordial genes that coded for tubulins likely were few in number. As metazoan evolution progressed, natural selection processes conserved multiple and mutant tubulin genes in response to the requirements for differentiated cell types (Sullivan, 1988). 

The MAPs vary in number and relative abundance in different cell types MAP2 is principally found in dendrites, whereas tau is restricted to axons. This selective distribution of MAP2 molecules is the result of subcellular sorting of its messenger RNA (Lewis et al., 1989). Currently, there is interest in the observation that tau is a component of the neurofibrillary tangles of Alzheimer s disease (Goedert et al., 1989). 

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