Small bowel obstruction and the gastrografin challenge.

The "gastrografin challenge" has been used for decades in the evaluation of small bowel obstruction (SBO). This type of study involves enteric administration of a water-soluble contrast followed by serial abdominal radiographs. While its diagnostic role is well established, its therapeutic role remains controversial. Following an algorithm for gastrografin challenge cases can help with interpretation. An understanding of the appearance of diluted contrast in the small bowel, the concentrating effect of contrast in the colon, and knowledge of surgical history and anatomy is paramount for diagnosis. In this article, we review the approach to acute SBO and the use of gastrografin along with reviewing image interpretation of cases of partial and complete SBO. Gastrografin use in adynamic ileus along with other potential future uses is also discussed.

Making time count: functional evidence for temporal coding of taste sensation.

Although the temporal characteristics of neural responses have been proposed as a mechanism for sensory neural coding, there has been little evidence thus far that this type of information is actually used by the nervous system. Here the authors show that patterned electrical pulses trains that mimic the response to the taste of quinine can produce a bitterlike sensation when delivered to the nucleus tractus solitarius of behaving rats. Following conditioned aversion training using either "quinine simulation" patterns of electrical stimulation or natural quinine (0.1 mM) as a conditioned stimulus, rats specifically generalized the aversion to 2 bitter tastants: quinine and urea. Randomization of the quinine simulation patterns resulted in generalization patterns that resembled those to a perithreshold concentration (0.01 mM) of quinine. These data provide strong evidence that the temporal pattern of brainstem activity may convey information about taste quality and underscore the functional significance of temporal coding.