Mammal cell lines

In mammals, ciliated cells line the respiratory air passages, the fallopian tubes, and the ventricles of the brain. The cilia beat in a coordinated manner in waves that propel fluids, suspended cells, and small particles along a surface. The motility of the sperm cell is provided by a single flagellum. 

Human viruses will cause disease in other animals. Some are capable of infecting only a few closely related primate species, others will infect a wide range of mammals. Under the conditions of natural infection vimses generally exhibit a considerable degree of tissue specificity. The influenza vims, for example, replicates only in the cells lining the upper respiratory tract. 

CNTs have been studied for cancer therapies despite the fact that these have been shown to accumulate to toxic levels within the organs of diverse animal models and different cell lines (Fiorito et al., 2006 Tong and Cheng, 2007). The molecular and cellular mechanisms for toxicity of carbon nanotubes have not been fully clarified. Furthermore, toxicity must be examined on the basis of multiple routes of administration (i.e., pulmonary, transdermal, ocular, oral, and intravenous) and on multiple species mammals, lower terrestrial animals, aquatic animals (both vertebrates and invertebrates), and plants (both terrestrial and aquatic). A basic set of tests for risk assessment of nanomaterials has been put forward (Nano risk framework). 

Even greater flexibility was achieved by genetic fusion of streptavidin with protein A [153,154]. Protein A specifically binds the Fc domain of IgG immunoglobulins of almost all mammals without inhibiting the antigen binding activity of the antibody. The streptavidin-protein A fusion construct was used for the assembly of complexes of biotinylated P-galactosidase and different monoclonal antibodies specific for tumour cell receptors. As a result these complexes were efficiently delivered into several cancer cell lines [154]. 

The maximum hormetic stimulatory response is typically a 30%-60% increase of the control value, and this appears to be the case across systems, whether the system is a plant, fish, cell line, mammal, or bacteria. The hormetic response is typically observed at dose levels at 1/10-1/5 of the NOAEL and up to just below the NOAEL. The frequency with which hormesis occurs in toxicity smdies may be quite high. An analysis of several hundred articles selected from a large database of published toxicity studies showed a frequency of 40% (Calabrese 2005). 

TRPA1 is the only member of the TRPA subbranch of the TRP gene family in mammals. This ion channel is characterized by a large number of ankyrin repeats ( 17) in its cytosolic N-terminus, a TRP channel membrane domain, and a short cytosolic C-terminal domain. The transcript of TRPA1 was initially identified in a cell line derived from a lung tumor (Jaquemar, Schenker et al. 1999). However, its functional role in these cells has not been studied further, and expression in lung tissue could not be confirmed. 

Although animal models can provide important information regarding the bioavailability and pharmacology of potential anticancer drugs in mammals, they are not always accurate predictors of activity against human tumor cells. In one report [27], the activity of a series of isomeric [l,2-bis(di-fluorophenyl)ethylenediamine]dichloroplatinum(II) compounds was evaluated in MXT murine mammary carcinomas in vivo the same compounds were also tested against several human cell lines in culture. The in vivo screen revealed a 2,6-difluoro-substituted compound to be the most active, whereas the 2,4-difluoro-substituted compound was most active against the human breast-cancer cell lines. It was concluded that the mouse mammary carcinoma is not an appropriate model for human breast cancers. Extreme caution must be employed when animal tumor results are used to predict activity in human tumors. 

A number of microcarrier systems have been estabhshed with primary and secondary cells from birds and mammals, permanent cell lines from fish and mammals as well as diploid human cells (Reuveny, 1985). A further possibility is the mass production of cells with the retention of differentiation potential, as can be seen with bone cells (Sautier et aL, 1992) and human retinal pigment epithelial cells (Kuriyama et aL, 1992). In addition to the widely used continuous cell lines for the production of biologicals, freshly harvested cells such as endothelial cells have been applied for the production of endothelium-derived relaxing factor (Bing et aL, 1991). 

The reabsorption of conjugated bile acids is mediated by ASBT, which is localized on the apical membrane of ileal enterocytes in mammals. ASBT is a drug target not only to lower plasma cholesterol level but also to improve intestinal permeability [46]. Although available monolayer cell lines do not express ASBT, it has been expressed in MDCK cells [47]. Human intestine also expresses multiple MCTisoforms [48]. These MCTs are responsible for the absorption of short-chain fatty acid. Expression of MCT in Caco-2 allows it to be an appropriate model to study short-chain fatty acid transport [9, 49, 50]. 

Several classes of molecules are involved in metal homeostasis. Metallothioneins (MTs) are a family of cysteine-rich metal-binding proteins that in mammals appear to function in Zn homeostasis and protect against heavy metal toxicity and oxidative stress60. Glutathione (GSH) is a sulfhydryl-rich tripeptide that is generally involved in the protection of cells against toxicants and in the metabolism of xenobiotics71. MTs and GSH are found in fish, and their expression and functions have been conveniently studied with piscine cell lines. 

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