PubMed · 5052898
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R O Davies, D P Zarowny, H R Robin, J Ruedy. 1972-08-05. Bioavailability.. https://pubmed.ncbi.nlm.nih.gov/5052898/
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Gene therapy is a promising process for the prevention, treatment and cure of diseases such as cancer, acquired immunodeficiency syndrome (AIDS) and cystic fibrosis. One of the methods used to administer therapeutic genes is the direct injection of naked or lipid-coated plasmid DNA, but this requires considerable amounts of plasmid DNA. There are several problems and bottlenecks associated with the design and operation of large-scale processes for the production of pharmaceutical-grade plasmid DNA for gene therapy.
The work reported in this article was undertaken to evaluate the utility of SAS PROC.MIXED for testing hypotheses concerning GROUP and TIME x GROUP effects in repeated measurements designs with drop-outs. If dropouts are not completely at random, covariate control over informative individual differences on which dropout data patterns depend is widely recognized to be important. However, the inclusion of baseline scores and time-in-study as between-subject covariates in an otherwise well formulated SAS PROC.MIXED model resulted in inadequate control over type I error in simulated data with or without drop-outs present. The inadequate model formulations and resulting deviant test sizes are presented here as a warning for others who might be guided by the same information sources to employ similar model specifications when analyzing data from actual clinical trials. It is important that the complete model specification be provided in detail when reporting applications of the general linear mixed-model procedure. A single random-coefficients model produced appropriate test sizes, but it provided inferior power when informative covariates were added in the attempt to adjust for dropouts. As an alternative, the incorporation of covariate controls in simpler two-stage endpoint or random regression analyses is documented to be effective in dealing with dropouts under specifiable conditions.
The trends of new drug development in the 21st century were described. First, the history of drug development including that of the drug delivery system (DDS) was shown. Then, the recent drugs and therapeutic technology were discussed in detail. These topics are biomedicine, gene related technology, vaccine, hybrid artificial organ, chemical and phage library, fetal growth hormone, cell therapy, humanized anti-body and Viagra. In addition, some natural products were introduced, emphasizing the relationship between food and human health. Finally, I stated my opinion about the new drug development in the 21st century in Japan.