Involvement of liver aldehyde oxidase in conversion of N-hydroxyurethane to urethane

The present study provides the evidence that liver aldehyde oxidase in the presence of its electron donors can catalyze the reduction of N-hydroxyurethane to urethane under anaerobic conditions. Guinea pig liver 9000 X g supernatant and cytosol, but not liver microsomes, exhibited N-hydroxyurethane reductase activity in the presence of acetaldehyde or 2-hydroxypyrimidine. The cytosolic enzyme was precipitated with ammonium sulfate between 30 and 45% ammonium sulfate saturation. The N-hydroxyurethane reductase and aldehyde oxidase activities of the precipitate were similarly susceptible to inhibition by a variety of chemicals. When the precipitate was chromatographed on a DEAE-cellulose column, the elution peak position of N-hydroxyurethane reductase was entirely identical with that of aldehyde oxidase. Furthermore, purified rabbit liver aldehyde oxidase also exhibited a significant N-hydroxyurethane reductase activity in the presence of acetaldehyde or 2-hydroxypyrimidine.

Gardner's syndrome associated with periampullary carcinoma, duodenal and gastric adenomatosis. Report of a case

A 48-year-old man with Gardner's syndrome, who had abdominoperineal resection for rectal carcinoma in 1962, was found to have an ulcerating growth of the duodenum, and pancreaticoduodenectomy was performed in 1979. Histologic examination by complete step-serial sectioning disclosed a well-differentiated adenocarcinoma with adenomatous remnants, a large adenoma with focal carcinoma, 256 adenomas of the duodenum, and 91 adenomas of the gastric antrum. The world medical literature was reviewed, and 29 cases of periampullary carcinoma and 12 cases of gastric carcinoma complicating familial polyposis coli or Gardner's syndrome were analyzed.

Metabolism of N-hydroxyurethane by guinea pig liver preparations

The present study demonstrated the metabolism of N-hydroxyurethane by cell-free preparations, i.e., 9000 X g supernatant, cytosol and microsomes, from guinea pig livers. Under anaerobic conditions, the metabolizing activities of these preparations were enhanced markedly by addition of both an NADPH- or NADH-generating system and FAD. When the 30-45% ammonium sulfate fraction from liver cytosol was combined with liver microsomes or milk xanthine oxidase, the metabolic reaction of N-hydroxyurethane proceeded to a greater extent. Thin-layer chromatographic examination showed that urethane was only a metabolite formed from N-hydroxyurethane by these preparations.

Mathematical structures of line drawings of polyhedrons-toward man-machine communication by means of line drawings

Mathematical structures of line drawings of polyhedrons are studied and practical as well as theoretical solutions are obtained for several fundamental problems aroused in scene analysis and in man-machine communication. First, a necessary and sufficient condition for a line drawing to correctly represent a polyhedron is obtained in terms of linear algebra. Next, combinatorial structures are investigated and practical solutions are obtained to such problems as how to discriminate between correct and incorrect line drawings and how to correct vertex-position errors in incorrect line drawings. Lastly, distribution of the degree of freedom of a line drawing is elucidated and a method is proposed for interactive reconstruction of a polyhedron from a line drawing. The results obtained here enable us to make manmachine communication more ``flexible'' in the sense that a machine can reconstruct three-dimensional objects from hand-drawn pictures even if the pictures are not perfect.

Classification of impossible objects

A mathematical scheme is proposed for the classification of impossible objects. Impossible objects are usually defined from a psychological point of view as mental images of 'solid objects' which cannot exist in a real three-dimensional world. From the mathematical point of view, however, various kinds of impossibility can be observed in such objects, and they are classified according to the kinds of impossibility they possess. Since impossible objects are treated in a purely mathematical way, the results afford a powerful basis for the psychological study of human visual perception of impossible objects. Several psychological problems arising from the present results are also discussed.