Work in progress. Gastrointestinal ulcerations: detection using a technetium-99m-labeled ulcer-avid agent.

Technetium-99m-labeled sucralfate, an ulcer-avid material, was shown in preliminary animal and human studies to be stable in vivo with good sensitivity. Eight experimentally produced discrete gastric ulcers in three rabbits were visualized using this material. Of seven human studies, four studies were true-positive and three were true-negative. It is suggested that Tc-99m-labeled sucralfate may prove to have significant clinical advantages for the evaluation of gastrointestinal ulcer disease and other diseases that are associated with loss of mucosal integrity. The method for labeling sucralfate with Tc-99m was developed by the authors.

The anaerobic decomposition of benzoic acid during methane fermentation. III. The fate of carbon four and the identification of propanoic acid.

Anaerobic rupture of the benzoic acid ring was investigated. Carbon 4 was converted primarily to carbon dioxide. Following ring rupture during methane fermentation, propanoic acid is an intermediate, and carbon 4 of benzoate becomes its carboxyl.

The anaerobic decomposition of benzoic acid during methane fermentation. IV. Dearomatization of the ring and volatile fatty acids formed on ring rupture.

A possible pathway for the anaerobic utilization of benzoic acid by a methanogenic consortium is suggested. Cyclohexane carboxylic acid and 1-cyclohexene-1-carboxylic acid have been identified as intermediates before ring rupture. Suprisingly, 3-cyclohexene-1-carboxylic acid interferes with utilization of other cyclic acids. In addition, isobutyric acid or short chain acids containing carbon-carbon double bonds could not be used without induction periods of a week or longer. A number of volatile fatty acids (heptanoic, valeric, butyric, propanoic, and acetic) have been identified and are suggested intermediates.