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The recent focus of federal funding on comparative effectiveness research underscores the importance of clinical trials in the practice of evidence-based medicine and health care reform. The impact of clinical trials not only extends to the individual patient by establishing a broader selection of effective therapies, but also to society as a whole by enhancing the value of health care provided. However, clinical trials also have the potential to pose unknown risks to their participants, and biased knowledge extracted from flawed clinical trials may lead to the inadvertent harm of patients. Although conducting a well-designed clinical trial may appear straightforward, it is founded on rigorous methodology and oversight governed by key ethical principles. In this review, we provide an overview of the ethical foundations of trial design, trial oversight, and the process of obtaining approval of a therapeutic, from its pre-clinical phase to post-marketing surveillance. This narrative review is based on a course in clinical trials developed by one of the authors (DJM), and is supplemented by a PubMed search predating January 2011 using the keywords “randomized controlled trial,” “patient/clinical research,” “ethics,” “phase IV,” “data and safety monitoring board,” and “surrogate endpoint.” With an understanding of the key principles in designing and implementing clinical trials, health care providers can partner with the pharmaceutical industry and regulatory bodies to effectively compare medical therapies and thereby meet one of the essential goals of health care reform.

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TAL (transaldolase) was originally described in the yeast as an enzyme of the PPP (pentose phosphate pathway). However, certain organisms and mammalian tissues lack TAL, and the overall reason for its existence is unclear. Recently, deletion of Ser(171) (TALDeltaS171) was found in five patients causing inactivation, proteasome-mediated degradation and complete deficiency of TAL. In the present study, microarray and follow-up Western-blot, enzyme-activity and metabolic studies of TALDeltaS171 TD (TAL-deficient) lymphoblasts revealed co-ordinated changes in the expression of genes involved in the PPP, mitochondrial biogenesis, oxidative stress, and Ca(2+) fluxing. Sedoheptulose 7-phosphate was accumulated, whereas G6P (glucose 6-phosphate) was depleted, indicating a failure to recycle G6P for the oxidative branch of the PPP. Nucleotide analysis showed depletion of NADPH and NAD(+) and accumulation of ADP-ribose. TD cells have diminished Deltapsi(m) (mitochondrial transmembrane potential) and increased mitochondrial mass associated with increased production of nitric oxide and ATP. TAL deficiency resulted in enhanced spontaneous and H(2)O(2)-induced apoptosis. TD lymphoblasts showed increased expression of CD38, which hydrolyses NAD(+) into ADP-ribose, a trigger of Ca(2+) release from the endoplasmic reticulum that, in turn, facilitated CD20-induced apoptosis. By contrast, TD cells were resistant to CD95/Fas-induced apoptosis, owing to a dependence of caspase activity on redox-sensitive cysteine residues. Normalization of TAL activity by adeno-associated-virus-mediated gene transfer reversed the elevated CD38 expression, ATP and Ca(2+) levels, suppressed H(2)O(2)- and CD20-induced apoptosis and enhanced Fas-induced cell death. The present study identified the TAL deficiency as a modulator of mitochondrial homoeostasis, Ca(2+) fluxing and apoptosis.