Liver ultrastructural changes following portal circulation disturbances

Liver cell changes produced in rats by the ligature of the portal vein and of the spleen pedicle were studied by electron microscopy. There were differences in the liver response to the various types of circulatory disturbances. The earliest and most marked lesions of hepatic cells were noticed in the case of portal vein ligature, and occurred at the level of rough endoplasmic reticulum, mitochondria and lysosomes. No significant changes in Kupffer cells. When the spleen pedicle was ligated, the hepatic cell changes were less obvious, but the Kupffer cells changes were more prominent, testifying and increased hetero- and autophagy.     

A new method for the quantification of superoxide dismutase mimics with an allopurinol–xanthine oxidase–lucigenin enhanced system

Allopurinol is a prodrug converted to oxypurinol by xanthine oxidase, a process followed by an efficient enzyme inhibition. Using a lucigenin-enhanced chemiluminescence method, we found that, under alkaline conditions, superoxide radicals are produced in large amounts in the first step of the interaction between the enzyme and the inhibitor. A comparison between lucigenin and cytochrome c as final detectors revealed that only the chemiluminescence technique is able to detect the superoxide anions from allopurinol oxidation. The allopurinol–xanthine oxidase–lucigenin system can be used for the quantification of various free-radical scavengers, in particular superoxide dismutase mimics. Three manganese compounds from different structural classes [manganese(II) chloride, manganese N,N′-bis(salicylidiene)ethylenediamine chloride, and manganese(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin] were compared at five concentrations (0.01, 0.1, 1, 10, and 100 μM). The method is fast, 16 times more sensitive than the cytochrome c assay at pH 10.1 and could be used for in vivo investigations avoiding the lucigenin redox cycle. If the concentrations of the reagents are increased and Tween 20 is added, the method is also operative at pH 7.4.