Chemoreceptor function and metabolism of the carotid body in the rat

Using fluorimetric and polarographic determination of cell respiration, metabolic reactions of the carotid body of rats to adequate stimulation have been revealed. Functional relationships of the dose--effect type, which were found for these reactions, may be approximated by equations which are similar to those describing the unconditioned reflexes from the carotid chemoreceptors. However, reactions of the metabolics systems of the carotid body account for the perception of not all chemical stimuli, but only of acids and some alkaloids. These data reveal the heteregeneity of the carotid chemosensory system not only in the amphibians (which was known earlier), but in mammals as well.     

Histochemical study of reverse reactions in experimental leprosy in armadillos

Morphological and histochemical characteristics of reverse reactions in M. leprae-infected armadillos are reviewed. The reverse reactions develop in generalized lepromatous disease and are characterized by a dramatic decrease in mycobacterial macrophage load and the appearance of lymphocytes, epithelioid and giant multinuclear cells with peripheral nucleus distribution. Histochemical investigation has shown a decrease in the activity of redox enzymes and alpha-naphthyl acetate esterase and an increase in beta-glucuronidase activity. The reverse reactions in the liver are accompanied by hepatic granuloma and hepatocyte destruction.     

Regulation of glyoxylate cycle enzymes in Saccharomycopsis lipolytica. I. Effect of the carbon source on isocitrate lyase and malate synthase activity

Comparative studies on the activities of isocitrate lyase (ICL) and malate synthase (MS) were carried out with Saccharomycopsis lipolytica incubating the yeast on media with different carbon sources. When cells were incubated in minimal medium with glucose, the activities of both enzymes were very low. In contrast, in minimal medium with acetate enhanced enzyme activities could be demonstrated. It is probably that the synthesis of ICL is repressed in presence of glucose. Furthermore the activity of ICL was inhibited by tricarboxylic acid cycle intermediates like succinic acid and oxalacetic acid. It was concluded that the syntheses of enzymes are derepressed. When cells of Sm. lipolytica were incubated in minimal medium with acetate, a high enzyme activity is evident. Synthesis of ICL on acetate was inhibited by cycloheximide and actinomycin D. The results were discussed comparing them with data obtained from other organisms.