Cell culture bioassays

The q2 value of a CoMFA model, together with other statistical information from the pis analysis, provides information on the predictive capability of the model. In this study we have generated CoMFA models that describe the pharmacophore either with or without the involvement of hemin, both of which provide good q2 values. Selection of the model that most accurately depicts reality is not trivial since many variables are inherent in the cell-culture bioassay results. However, it may be... 

Other equally important methods are the electrophoretic techniques, such as polyacrylamide gel electrophoresis, isoelectric focusing, Western blots, combined electrophoresis, and isoelectric focusing (two-dimensional electrophoresis). Bioactivity methods are other key methods used in biotechnology product development. These include in vivo whole animal bioassay, cell culture bioassay, immunoassay, and biochemical assay. Many references and several textbooks are available in many industrial and academic libraries to provide additional and up-to-date information. 

By definition, the experimental unit is the smallest unit randomly allocated to a distinct level of a treatment factor. Note that if there is no randomization, there is no experimental unit and (in nearly all cases) no experiment. Although it is possible to perform experiments without randomization, it is difficult to do well, and risky unless the experimental system is very well understood (7). Randomization is important for several reasons. Randomization changes the sources of bias into sources of variation in general, a noisy assay is better than a biased assay. Further, randomization allows estimates of variation to represent variation in the population this in turn justifies statistical inference (standard errors, confidence intervals, etc.). A common practice in cell-culture bioassay is to rotate among a small collection of layouts rather than use random allocation. Whereas rotation among a collection of layouts is certainly better than a fixed layout, it is both possible and practical to use carefully structured randomization on a routine basis, particularly when using a robot. 

Biological assays are often noisy and laborious. With careful application of experimental design, cell culture bioassays can be made quite accurate and precise. The core information needed for validation can come from two experiments. One experiment studies accuracy and precision followed by a variance component analysis and a summary table that describes the expected performance of the system at various levels of replication. A second experiment uses a minimal fractional factorial design to study robustness, followed by a comparison of confidence intervals on effect sizes with a previously established indifference zone. 

Continuous culture systems have been widely used to culture microorganisms for industrial and research purposes (Kubitschek 1970 Tempest 1970 Veldkamp 1976 Rhee 1980). In recent years, these culture techniques have found their way into the bioassay methods of ecotoxicology and allelopathy (Rhee 1980). The early development of a continuous culture system can be traced back to the work of Novik and Szilard (1950 a,b) who developed the first chemostat. In a continuous culture system, nutrients are supplied to the cell culture at a constant rate and to maintain a constant volume, an equal volume of cell culture is removed. This allows the cell population to reach a steady state, where the growth rate and the total number of cells/ml of culture remains constant. Two kind of continuous culture systems can be distinguished turbidostat and chemostat. ... 

III. In vitro biological activity specificity and efficiency Cell culture Demonstrate specific antisense effect by various bioassays such as anti-viral and anti-proliferation effect, induction of apoptosis... 

Bioassays appeared to fit the bill to perform this service to monitor chemical contamination. They have been around for a while. Until relatively recently, however, they remained in the realm of the laboratory. Only over the last two decades have they found a niche in testing for toxic chemicals in water and sediment, but not yet specifically as a tool for routine water quality monitoring. As Small-scale Freshwater Toxicity Investigations, Volumes 1 and 2 amply demonstrates, the science has now come of age. Assays based on bacteria, microscopic or multi-cellular algae, protozoa, invertebrates and vertebrates (freshwater fish cell cultures) are discussed in... 

KW Brown Texas A M University Utilize bioassays, mammalian cell cultures, and human lymphocyte cultures to measure the genotoxicity, immunotoxicity, developmental toxicity, and 2,3,7,8-TCDD-induced toxicity of sample extracts from Superfund sites ... 

Special emphasis on bioassays performed in cell culture. 

Cell culture technology can be a viable alternative to animal testing in many cases, with the possibility of increasing significantly the number of replicate samples and thus expanding the bioassay utility. Primary cell cultures have the advantage that they maintain most of the characteristics of the animal tissue from which the cells are derived. These would be ideal for bioassays except that they cannot be kept in culture indefinitely. They can be difficult and sometimes impossible to grow reproducibly, and are subject to the inherent variability of the animal they come from. 

At the heart of any search for bioactive molecules is the need for effective bioassays. Several bioassays have been developed for the identification of compounds with anti-juvenile hormone (AJH) activity. The most common of these AJH bioassays involves the treatment of young larvae or nymphs with the potential AJH by incorporation into the diet or contact application, and then waiting for several days (or, in some cases, weeks) for precocious development (or other AJH response) to occur ( 1, ). Alternatively, AJH activity can be determined using jri vitro assays such as corpora allata cultures or epidermal cell cultures to monitor for inhibition of juvenile hormone (JH) biosynthesis (3-6) or blockage of the JH induced inhibition of pupal commitment (7), respectively. 

Many different bioassays and biochemical or genetic tests have been developed to identify resistant weeds. However, these are normally conducted after the suspected development of resistance, not in a proactive or preventive manner. The potential for evolution of resistance to a new herbicide can be examined in several ways wild-type populations can be screened for resistant individuals, model plant populations can be muta-genized and screened for resistance, resistant cells can be selected in culture, with or without prior exposure to the herbicide, or biochemical or genetic assays can be used to identify known resistance mechanisms. However, more complex or obscure resistance mechanisms may exist, and certain mechanisms may only be expressed in whole plants, not in cell cultures. More recent techniques focused on rapid genetic evolution can also provide a clue to the relative ease with which resistance can be generated, but still require a large investment. However, as in many predictive studies, it is often difficult to relate the results of such experiments to resistance evolution in the field. 

PCDTs were shown to be considerably less toxic than 2378-TeCDD and the most toxic PCDFs or PCBs. The compound 2378-TeCTA, the sulfur analogue of 2378-TeCDD, has been suggested to have dioxin-like activity Bioassays which detect the ability of 2378-TeCDD and related compounds to inhibit cell divisions in a mouse epithelial cell culture were used [8], In in vivo studies 2378-TeCTA has been shown to be less toxic than 2378-TeCDD [61]. 

Bioassays, receptor assays, and immunoassays are used to measure GH. ° Most bioassays assess GH activity by analyzing a variety of growth-related metabohc changes in hypophysectomized rats or in cell cultures. A relatively simple and convenient bioassay, the Nb2 cell assay, uses cultures of GH-sensitive rat lymphoma cells.These bioassays are used primarily for calibrating GH reference materials or for comparing the biological potency and immunoreactivity of GH fragments and synthetic peptides. Receptor assays have also been applied to the measurement of GH, but their use has been limited to research applications. 

---