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Splenda is comprised of the high-potency artificial sweetener sucralose (1.1%) and the fillers maltodextrin and glucose. Splenda was administered by oral gavage at 100, 300, 500, or 1000 mg/kg to male Sprague-Dawley rats for 12-wk, during which fecal samples were collected weekly for bacterial analysis and measurement of fecal pH. After 12-wk, half of the animals from each treatment group were sacrificed to determine the intestinal expression of the membrane efflux transporter P-glycoprotein (P-gp) and the cytochrome P-450 (CYP) metabolism system by Western blot. The remaining animals were allowed to recover for an additional 12-wk, and further assessments of fecal microflora, fecal pH, and expression of P-gp and CYP were determined. At the end of the 12-wk treatment period, the numbers of total anaerobes, bifidobacteria, lactobacilli, Bacteroides, clostridia, and total aerobic bacteria were significantly decreased; however, there was no significant treatment effect on enterobacteria. Splenda also increased fecal pH and enhanced the expression of P-gp by 2.43-fold, CYP3A4 by 2.51-fold, and CYP2D1 by 3.49-fold. Following the 12-wk recovery period, only the total anaerobes and bifidobacteria remained significantly depressed, whereas pH values, P-gp, and CYP3A4 and CYP2D1 remained elevated. These changes occurred at Splenda dosages that contained sucralose at 1.1-11 mg/kg (the US FDA Acceptable Daily Intake for sucralose is 5 mg/kg). Evidence indicates that a 12-wk administration of Splenda exerted numerous adverse effects, including (1) reduction in beneficial fecal microflora, (2) increased fecal pH, and (3) enhanced expression levels of P-gp, CYP3A4, and CYP2D1, which are known to limit the bioavailability of orally administered drugs.

Center WITNESSING THE SWIFT ADVANCES in the electronic means of seeing and hearing, scientists and engineers scent a market for systems mimicking the human nose. Already commercial systems from several companies are targeting applications, present and potential, that range from quality assurance of food and drugs to medical diagnosis, environmental monitoring, safety and security, and military use. The harnessing of electronics to measure odor is greatly to be desired. Human panels backed by gas chromatography and mass spectrometry (GC/MS) are helpful in quantifying smells, but they are time-consuming, expensive, and seldom performed in real time in the field. So it is important that these traditional methods give way to a speedier procedure using an electronic nose composed of gas sensors. To be sure, gas sensors have been around for many years. But today's electronic nose technology goes several steps farther. Arrays of sensors that respond to a wide range of compounds are used, as well as advanced pattern recognition and artificial intelligence techniques, which enable users to readily extract relevant and reliable information. So-called electronic noses-systems that detect and identify odors and vapors, typically by linking chemical sensing devices with signalprocessing and pattern-recognition subsystems-go for US $20 000 to $100 000 in Europe, the United States, and Japan, predominantly for laboratory use. Advances in the technology have been made ever since the early 1980s when researchers at the University of Warwick in Coventry, England, developed sensor arrays for odor detection. Focused primarily on the sensor aspect of the problem, the initial research explored the use of metal oxide devices. Later work at Warwick University explored the use of conducting polymers. In both, sensing is based on conductivity changes. Those early efforts have spawned several commercial enterprises. In August 1991, the pioneers organized an advanced research workshop in Reykjavik, Iceland, sponsored by the North Atlantic Treaty Organization. The workshop accelerated interest in the field, and by now there are many groups around the world working on electronic nose technology. The Warwick pioneers envisioned an actual electronic equivalent of the mammalian olfactory system and dubbed their primitive analogs of it the electronic nose. So even though the electronic system resembles its biological counterpart none too closely, the "electronic nose"-or E-nose-label has been widely adopted around the world. The biological nose To attempt to mimic the human apparatus, researchers have identified distinct steps that characterize the way humans smell [see "Design for smelling" by Wolfgang Göpel and Tilo Weiss]. It all begins with sniffing, which moves air samples that contain molecules of odors past curved bony structures called turbinates. The turbinates create turbulent airflow patterns that Receptor: a molecular structure on the surface of a nerve cell to which specific compounds can bind; also a sensory nerve terminal that resp...

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