Taste receptors in the gastrointestinal tract. V. Acid sensing in the gastrointestinal tract

Luminal acidity is a physiological challenge in the foregut, and acidosis can occur throughout the gastrointestinal tract as a result of inflammation or ischemia. These conditions are surveyed by an elaborate network of acid-governed mechanisms to maintain homeostasis. Deviations from physiological values of extracellular pH are monitored by multiple acid sensors expressed by epithelial cells and sensory neurons. Acid-sensing ion channels are activated by moderate acidification, whereas transient receptor potential ion channels of the vanilloid subtype are gated by severe acidosis. Some ionotropic purinoceptor ion channels and two-pore domain background K(+) channels are also sensitive to alterations of extracellular pH.     

Urinary tract morphometry. An overview

An overview is presented of the application of morphometry to conditions in the urinary tract, with the work of a number of researchers briefly summarized. The data discussed show that morphometric techniques are already being successfully applied in the differential diagnosis and grading of some diseases of the prostate, urinary bladder and kidney. In the prostate, nonneoplastic changes can be differentiated from neoplasms and prostatic carcinomas can be more precisely graded. Both cytologic and histologic preparations of bladder carcinomas can be graded by morphometric techniques. Morphometry has found another application in assisting in the distinction between normal kidneys and those with "minimal-change" disease. The specific criteria pertaining to the use of morphometric methods in each of these situations are also discussed.