Tissue culture systems

Fibroblast locomotion has been studied in tissue culture systems and is unexpectedly complex. Initially when fibroblasts are plated, they are rounded and... 

The long incubation times of many human virus diseases indicate that they replicate slowly in host cells. In tissue culture systems it has been shown that most human viruses take from 4 to 24 hours to complete a single replication cycle, contrasting with the 30 or so minutes for many bacterial viruses. 

Metabolic control analysis (MCA) assigns a flux control coefficient (FCC) to each step in the pathway and considers the sum of the coefficients. Competing pathway components may have negative FCCs. To measure FCCs, a variety of experimental techniques including radio isotopomers and pulse chase experiments are necessary in a tissue culture system. Perturbation of the system, for example, with over-expression of various genes can be applied iteratively to understand and optimize product accumulation. 

In this review, we focus on the use of plant tissue culture to produce foreign proteins that have direct commercial or medical applications. The development of large-scale plant tissue culture systems for the production of biopharmaceutical proteins requires efficient, high-level expression of stable, biologically active products. To minimize the cost of protein recovery and purification, it is preferable that the expression system releases the product in a form that can be harvested from the culture medium. In addition, the relevant bioprocessing issues associated with bioreactor culture of plant cells and tissues must be addressed. 

A vector that facilitates high-level protein expression in plant tissue culture, particularly a transient expression system that could be applied to existing wild-type cultures, would be advantageous for in vitro foreign protein production. However, such a system has not yet been developed. The success of this approach depends in part on whether appropriate levels of viral infection, replication and transmission can be established within tissue culture systems. 

Proteins produced in plant cells can remain within the cell or are secreted into the apoplast via the bulk transport (secretory) pathway. In whole plants, because levels of protein accumulated intracellularly, e. g. using the KDEL sequence to ensure retention in the endoplasmic reticulum, are often higher than when the product is secreted [58], foreign proteins are generally not directed for secretion. However, as protein purification from plant biomass is potentially much more difficult and expensive than protein recovery from culture medium, protein secretion is considered an advantage in tissue culture systems. For economic harvesting from the medium, the protein should be stable once secreted and should accumulate to high levels in the extracellular environment. 

The simplicity of plant culture media is considered an advantage for foreign protein production in tissue culture systems. However, as a mixture of salts and sugar containing several heavy metals but negligible protein (except for any protein secreted... 

Goldberg AM. 1980. Mechanisms of neurotoxicity as studied in tissue culture systems. Toxicology 17 201-208. 

Not recognizing the need for special media or isolation techniques (eg, charcoal yeast extract agar for isolation of legionella species, shell-vial tissue culture system for rapid isolation of cytomegalovirus)... 

Tissue culture has been used to a limited extent for developmental toxicity studies of the studies that have used tissue culture systems, those using chick neural crest cells (Greenberg, 1982) and human embryonic palatal mesenchyme (Pratt et al., 1980, 1982) have been especially useful. In addition, the micromass teratogen test, first described by Flint Orton (1984), has been used as a screening tool, and this test has been used successfully for many years. This method uses cultures of limb and CNS cells. Rat cells are normally used, but mouse and chick cells have also been studied. Many different endpoints can be assessed. For a detailed description of the method, the validation studies and discussion of its predictive value, see Flint... 

For large-scale culture, inoculum size is one of the most significant factors affecting plant cell/tissue culture systems. Figure 8 shows the time course of the change in growth rate as inoculum size in bioreactor cultures. 

The mechanism of vanadium interaction with growth and differentiation pathways has been extensively studied [70], In tissue culture systems, vanadium has been shown to inhibit growth and, in some cases, modify DNA synthesis to block the G2-to-M transition. Cells blocked at M phase are susceptible to apoptosis, which can be stimulated by vanadium compounds. Vanadium compounds have also been shown to have mitotic effects stimulating growth, cell proliferation, or cell transformation. In some cases, vanadium compounds were able to promote cellular differentiation. Clearly, the addition of vanadium compounds would not have all of these... 

Radical scavengers such as a-tocopherols prevent oxidative degradation of HA. In tissue culture systems, the addition of Vitamin E to the medium prevents spontaneous degradation of HA,272 as does superoxide dismutase. In Vitamin-E-deficient animals, there is a decrease in GAGs in tissues, including HA 273 This could be reversed by the addition of Vitamin E to diets,274 suggesting that tocopherol supplements can enhance HA in human skin. 

It is speculated that this mass substitutes for the suspensor, an organ that normally aids in feeding developing embryos in plants. Recalcitrant soybean and cereal tissue culture systems are currently being investigated for evidence that these kinds of proregenerative cell masses are formed (4). 

Rationale for Using a Tissue Culture System in Metal Carcinogenesis Testing... 

Histiotypic The in vitro resemblance, of cells in culture, to a tissue in form or function or both. For example, a suspension of fibroblast-like cells may secrete a glycosaminoglycan-collagen matrix and the result is a structure resembling fibrous connective tissue, which is, therefore, histiotypic. This term is not meant to be used along with the word culture . Thus, a tissue culture system demonstrating form and function typical of cells in vivo would be said to be histiotypic. 

Human skin equivalents have been developed by several laboratories. One equivalent, Testskin, consists of human keratinocytes seeded onto a collagen base or collagen-glycosaminoglycan matrix containing human fibroblasts. In many respects, the epidermis which develops resembles epidermis in vivo. The tissue culture system survives for several weeks and may be useful in studying skin penetration. Testskin is a commercially produced skin equivalent system marketed by Organogenesis, Inc. (Cambridge, MA) ... 

Hong, Y. C. and Harlander, S.K. Plant Tissue Culture Systems for Flavor Production. In Flavor Chemistry of Lipid Foods (Min, D.B. and Smouse, T.H., eds.). The American Oil Chemists Society, Champaign, pp. 348- 366 (1989)... 

Borchardt, R. T. 1990. Assessment of transport barriers using cell and tissue culture systems. Drug. Dev. Ind. Pharm. 16 (8) 2595-2612. 

Ability to attain high-density growth in tissue-culture systems... 

It also is possible to use intact ceils as a source of xenobiotic metabolizing enzymes. Activation for tissue culture systems can be provided by primary rat liver cells and irradiated hamster embryo cells which are plated as a feeder layer for the indicator cells. In the case of compounds which yield a spec-... 

Using the three-chamber tissue culture system (Campenot, 1977) we tested the neurotrophic properties of ACTH 4-10, Org 2766 and BIM 22015 on dissociated, mixed cells of the spinal... 

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