Background: Controlled clinical trials of health care interventions are either explanatory or pragmatic. Explanatory trials test whether an intervention is efficacious; that is, whether it can have a beneficial effect in an ideal situation. Pragmatic trials measure effectiveness; they measure the degree of beneficial effect in real clinical practice. In pragmatic trials, a balance between external validity (generalizability of the results) and internal validity (reliability or accuracy of the results) needs to be achieved. The explanatory trial seeks to maximize the internal validity by assuring rigorous control of all variables other than the intervention. The pragmatic trial seeks to maximize external validity to ensure that the results can be generalized. However the danger of pragmatic trials is that internal validity may be overly compromised in the effort to ensure generalizability. We are conducting two pragmatic randomized controlled trials on interventions in the management of hypertension in primary care. We describe the design of the trials and the steps taken to deal with the competing demands of external and internal validity.

An immunoglobulin E (IgE)-dependent histamine-releasing factor (HRF) produced by lymphocytes of atopic children and present in biological fluids of allergic patients has been identified and purified. Amino-terminal sequencing revealed extensive homology to a mouse protein, p21, and its human homolog, p23. Both recombinant proteins caused histamine release from the human basophils of a subpopulation of donors, and this release was dependent on IgE. Polyclonal antibodies recognized and removed the biological activity of recombinant and native HRF. HRF identifies a heterogeneity of IgE and is believed to play a prominent role in chronic allergic disease processes.

Carbon dioxide reforming of methane to synthesis gas was studied by employing a Ni/La2O3 catalyst as well as conventional nickel-based catalysts, i.e., Ni/γ-Al2O3, Ni/CaO/γ-Al2O3, and Ni/CaO. It is observed that, in contrast to conventional nickel-based catalysts, which exhibit continuous deactivation with time on stream, the rate of reaction over the Ni/La2O3 catalyst increases during the initial 2−5 h and then tends to be essentially invariable with time on stream. X-ray photoelectron spectroscopy (XPS) studies show that the surface carbon on spent Ni/Al2O3 catalyst is dominated by −C−C− species that eventually block the entire Ni surface, leading to total loss of activity. The surface carbon on the working Ni/La2O3 catalyst is found to consist of −C−C− species and a large amount of oxidized carbon. Both XPS and secondary ion mass spectrometry results reveal that a large fraction of surface Ni on the working Ni/La2O3 catalyst is not shielded by carbon deposition. FTIR studies reveal that the enhancement of the rate of reaction over the Ni/La2O3 catalyst during the initial 2−5 h of reaction correlates well with increasing concentrations of La2O2CO3 and formate species on the support, suggesting that these species may participate in the surface chemistry to produce synthesis gas. It is proposed that the interaction between nickel and lanthanum species creates a new type of synergetic sites at the Ni−La2O3 interfacial area, which offer active and stable performance of carbon dioxide reforming of methane to synthesis gas over the stated catalyst.