Permanent cells

The method involves cell fusion, and the resulting permanent cell line is called a hybridoma. Typically, B cells are obtained from the spleen of a mouse (or other suitable animal) previously injected with an antigen or mixture of antigens (eg, foreign cells). The B cells are... 

Some cell cultures prepared in this way will grow indefinitely, and can be established as permanent cell lines. Such cell cultures are most convenient for virus research because continuously available cell material can be available for research purposes. In other cases,... 

Edgell CJ, McDonald CC, Graham JB. Permanent cell line expressing human factor VUI-related antigen established by hybridization. Proc Natl Acad Sci USA. 1983 80 3734-3737. 

The nature of a preneoplastic cell in vitro is not defined clearly and, therefore, it is difficult to discriminate between normal and preneoplastic cells. Some aneuploid cell lines have been demonstrated as preneoplastic by their increased propensity to become neoplastic in vitro and in vivo (Barrett et al, 1984). For this reason, it is assumed that only early-passage, diploid cells are normal and that all aneuploid cell lines are preneoplastic. Whether establishment as a permanent cell liner per se is a preneoplastic alteration is unclear, especially if the cells remain diploid, an event which occurs only rarely. 

Tryptophan pyrolysates have also been found to induce sister chromatid exchanges in cultured mammalian cell lines. Tohda et al. (35) tested Trp-P-1, Trp-P-2, 2-Amino-6-methyldipyrido[l,2-oi 3, 2 -dj imidazole(Glu-P-1), and AaC in a permanent cell line of human lymphoblastoid cells. All four compounds were active at a concentration of 10 M, but inclusion of S9 mix was necessary. Similar results are reported by Sasaki, a. (34) in 2 human and Chinese hamster cell lines. 

The FBR is increased in the presence of bacteria, a secondary challenge to sensor biocompatibility.3 6 7 Initial bacterial association with an implant surface is quickly followed by more permanent cell attachment through cell surface adhesion... 

The ecdysteroid-responsive Kc permanent cell line was established from disrupted embryos of D. melanogaster [188], Consequently, it is not known what in vivo cell type (if any) they represent. However, the response (aggregation of cells, cessation of division and the formation of axon-like projections) is characteristic and can form the basis of a somewhat time-consuming bioassay [189], which has been used to compare the biological activities of 60 steroids, most of which were inactive. The biological activities of a number of ecdysteroids in this Kc-H cell bioassay are summarised in Table (4). 

Sealed and semi-permanent cells are most common, but variable pathlength cells are also available. A simple version of a liquid sample cell is the demountable Nujol cell which is suitable for qualitative examination of pastes or viscous liquids. The use of spacers in these devices may or may not be necessary, depending on the viscosity of the sample under investigation. NaCl, KBr, Csl, and polyethylene window materials are convenient if the sample does not contain water. A drop of liquid or paste is placed on one of the windows, and the two windows are clamped with front and back metal plates. Semi-permanent cells are suitable for quantitative work and can be cleaned easily after use (Fig. 5.2.1). 

The best-known window materials for liquid cells are listed below with the spectra accessibility range (in cm-1) given in parenthesis (1) NaCl (40000-590), (2) KBr (40000-340), (3) Csl (40000-200), (4) polyethylene (625-50), (5) ZnS, Irtran-2 (17000-835), (6) ZnSe (20000-600), (7) Ge (5500-600), (8) Si (8300-660), and (9) sapphire (50000-1780). Materials (l)-(3) are not suitable for aqueous solutions because of their high hygroscopicity. ZnS and ZnSe are suitable for use with acidic and alkaline solutions. The path length spacers are made of lead and are available with 0.025, 0.05, 0.1, 0.2, 0.5, and 1.0mm path lengths. Permanent cells have an amalgamated lead spacer between the... 

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 regenerative capacity of cells allows them to be classified into three groups labile, stable (or expanding), and permanent (or static) cells. Labile cells continue to proliferate throughout life stable cells retain this capacity but do not normally replicate and permanent cells cannot reproduce themselves... 

Bioassays are based on observations of physiological responses specific for the hormone being measured. In vivo bioassays usually involve the injection of test materials (such as blood or urine from a patient) into suitably prepared animals target gland responses, such as growth or steroidogenesis, are then measured. In vitro bioassays involve the incubation of tissue, membranes, dispersed cells, or permanent cell lines in a defined culture medium, with subsequent measurement of an appropriate hormone response. Most in vitro bioassays measure responses proximal or distal to a second messenger, such as stimulation of cAMP formation. Bioassays tend to be imprecise and are rarely necessary in clinical medicine. 

Therefore, it is advisable to choose a cellular model according to its representativeness only for some or at least one epithelial function rather than a model representative for the entire airway epithelium. Permanent cell lines have been used to investigate individual epithelial functions like transepithelial Na+, Cl", and water transport, barrier function, or secretory function. Those models are predictive in regard only to the tested function. However, they are quite valuable especially in approaches with a larger throughput, since a sufficient amount of cells with an appropriate and reproducible quality are relatively easy to obtain. The use of human cell lines holds the advantage that toxicants can be tested on cells of the relevant host species and that results from these experiments need not be scrutinized for interspecies compatibility. 

Metabolic capacity of some commonly used cultured and permanent cell lines [2,35,52]... 

Table 1 shows some animal cell lines that are commonly used in various applications. Creating a stable, permanent cell line is the first critical step in producing recombinant proteins for therapeutic and diagnostic applications. Hybridoma, commonly used in the production of MAh, are generated by fusing antibody-producing spleen cells, which have a limited life... 

Zahn, T., C. Hauck, J. Holzschuh and T. Braunbeck. Acute and sublethal toxicity of seepage waters from garbage dumps to permanent cell lines and primary cultures of hepatocytes from rainbow trout (Oncorhynchus mykiss). a novel approach to environmental risk assessment for chemicals and chemical mixtures. Zentbl. Hyg. Umweltmed. 196 455-479, 1995. 

The second group of tests comprises cell culture-based bioassays, which are more favorable in terms of standardization, costs and time consumption, but stiU exhibit variabihty of living cells. Permanent cell hnes are used to test (e.g., on microtiter plates) survival rates against exogenous stimuli as a function of the protective effect of the analyte in case of antiviral activity. In a similar analytical setting, viral activity can be tested. For interferon (IFN)... 

The permanent cells are difficult to clean and can become damaged by water. Pathlengths need to be calibrated regularly if quantitative work is to be undertaken. 

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