Studies of SV40-transformation and the Loss of Growth Factor Requirements

I found that SV40 transformation induced the loss of several specific growth factor requirements. In particular, SV40 transformed 3T3 fibroblasts had a significantly reduced growth requirement for insulin. A reduced insulin requirement was also observed in several other transformed cell lines. Dose response studies with insulin and insulin-like growth factors indicated that the mitogenic response to insulin is in all probability mediated by IGF-I receptors, and that the reduced insulin requirement observed in transformed fibroblasts actually reflects the loss of a strong IGF-I requirement. IGF-I is under strict pituitary-growth hormone control in vivo, and mediates many if not all of the growth promoting effects of growth hormone. A reduced IGF-I requirement may allow transformed fibroblasts to escape from this major humoral regulatory system. SV40 transformed cells also displayed a significantly diminished requirement for platelet-derived growth factor (PDGF). The loss of this particular growth factor requirement was found to be closely associated with the loss of density-dependent growth inhibition. Cell lines transformed by temperature sensitive mutants of SV40 exhibited a temperature sensitive loss of the PDGF requirement, indicating that SV40 T-antigen mediates this effect. Results pertaining to the temperature sensitivity of the insulin requirement were inconclusive. I found that SV40 could directly reduce the insulin requirement of 3T3 cells in a transformation assay based upon the stringent insulin requirement of 3T3 cells for colony formation. Several such insulin-transformants were isolated and characterized. Although all of these transformants expressed SV40 T-antigen, some of them retained anchorage-dependence and/or a partial PDGF requirement, unlike transformants obtained in the standard density of anchorage assays. A revertant of SV40 transformed 3T3 cells was found to have regained a very strong dependence upon insulin. This dependence was not overcome by re-transformation with Kirsten Murine Sarcoma virus, although retransformation did obviate both its density-dependent growth inhibition and PDGF requirement. Kirsten transformed 3T3 normally display a greatly reduced insulin requirement, indicating that this particular revertant may have suffered a cellular mutation that prevents transforming viruses from induced the reduced insulin requirement

Runway Safety Training Methods for Runway Incursion Prevention

The Federal Aviation Administration wants to educate pilots about Runway safety to prevent runway incursions. The number of runway incursions increased nearly 83% from 954 in 2011 to 1,744 by the end of 2017 (OIG, 2018). This experimental research project trained 20 pilots using three different methods of teaching (classroom, online, in a flight simulator) to determine which method most effectively taught pilots about a specific topic in aviation. The different training methods change the way the educational content is delivered and this change in delivery could impact how well the pilots learn the material (Cox, 2010). The participants were given a pre-training exam on runway safety to determine their initial knowledge level. Each pilot was assigned one training method and one week after training took a post-test examination. The classroom lecture was created by instructor Taylor, the simulator training regimen was created by the researcher, AOPA’s Runway Safety course was created by AOPA sponsored by the FAA (FAA (2), 2018 & AOPA, 2018). It was hypothesized that the simulator training would produce the best results as it is the combination of a situated and dynamic learning environment. The data was inconclusive as to which method trained pilots the most effectively. However, the data from the research did reveal that for the twenty participants, the simulator training did produce the highest average scores in this research. Flight time did not appear to be a factor affecting if the pilots increased their scores

MIP/MTMR14 and muscle aging

No abstract

Assessing the Impact of Non-Differential Genotyping Errors on Rare Variant Tests of Association

Background/Aims: We aim to quantify the effect of non-differential genotyping errors on the power of rare variant tests and identify those situations when genotyping errors are most harmful. Methods: We simulated genotype and phenotype data for a range of sample sizes, minor allele frequencies, disease relative risks and numbers of rare variants. Genotype errors were then simulated using five different error models covering a wide range of error rates. Results: Even at very low error rates, misclassifying a common homozygote as a heterozygote translates into a substantial loss of power, a result that is exacerbated even further as the minor allele frequency decreases. While the power loss from heterozygote to common homozygote errors tends to be smaller for a given error rate, in practice heterozygote to homozygote errors are more frequent and, thus, will have measurable impact on power. Conclusion: Error rates from genotype-calling technology for next-generation sequencing data suggest that substantial power loss may be seen when applying current rare variant tests of association to called genotypes