Francesco Aurelio Pisanti

Acetyl-Homocysteine-Thiolactone-Induced Increase of Superoxide Dismutase Counteracts the Effect of Subdiabetogenic Doses of Streptozocin

Acetyl-homocysteine-thiolactone (CYT) is an organic thio compound that exerts free radical scavenger activity and increases superoxide dismutase (SOD) activity. Administration of 32 mg CYT kg body wt day 30 days in rats increased SOD activity in erythrocytes by 126%, and in pancreatic islets by 202%. Treatment affected only the Cu-Zn fraction of the enzyme. Transmission electron microscope observations showed that the damage to the pancreatic beta cells induced by single or multiple subdiabetogenic doses of streptozocin (STZ) (45 mg/kg body wt) was attenuated in animals treated with CYT. This protective effect was not observed with 65 mg of STZ. The experimental results seem to support the hypothesis that pancreatic beta cells are particularly vulnerableto the effect of oxygen radicals and that the cytotoxic effect of STZ is related to free radical-induced peroxidation.

Superoxide dismutase activity in the BB rat: A dynamic time-course study

Diabetes produced spontaneously in the BB rat is similar to that observed in multiple low dose streptozocin-induced diabetes, both being characterized histologically by a lympho-monocytic infiltrate in the pancreatic islets (insulitis). Recent studies indicated that streptozocin acts through peroxidative patterns sensitive to superoxide dismutase (SOD) activity. We therefore conducted a time-course study to evaluate if SOD activity in the islets of Langerhans is related to the onset of diabetes in BB rats with varying degree of diabetes. It was found that SOD activity does not change with age nor with the onset of diabetes. However SOD activity in the islets of BB rats was significantly lower than in the control Wistars. This lower SOD activity may be a proneness factor that favors the development of the diabetic syndrome.

Administration of a nitric oxide synthase inhibitor does not suppress low-dose streptozotocin-induced diabetes in mice.

SummaryNitric oxide (NO) has been reported as being a key mediator of the autoimmune destruction of B-cells in type I diabetes, and studies have described a suppression of low-dose streptozotocin-induced (LDS) diabetes in mice after the use of NO synthase inhibitors. However, these studies disagree with regard to the outcome of hyperglycemia and insulitis after treatment with thesel-arginine analogs. The present study tries to clarify this topic by administeringN-nitro-l-arginine-methylester (NAME) (15 mg/d/mouse/15 d) after an LDS treatment in 108 male C57BL6/J mice.Glycemia measured at the end of the NAME treatment did show a slight, but significant, reduction when compared to LDS control animals (p<0.001), but values returned to diabetic levels 2 wk after withdrawal of NAME. Morphological observations demonstrated that the degree of infiltration and islet B-cell damage was absolutely not inhibited by NAME. In conclusion, treatment withl-arginine analogs is not capable of protecting mice from LDS-induced diabetes.

Adhesion Molecules and Microvascular Changes in the Nonobese Diabetic (NOD) Mouse Pancreas. An NO-Inhibitor (L-Name) is Unable to Block Adhesion Inflammation-Induced Activation

The aim of the present study was to investigate the immunoreactivity of pancreatic microvasculature with emphasis on the adhesion molecule expression in NOD mice at a very early stage and after the start of infiltration, before the onset of the diabetic disease. Immunoreactivity for Ia-b, BM8 (mouse macrophages) and inter-cellular-adhesion-molecule-1 (ICAM-1) molecules in untreated control mice and in animals treated using an inhibitor of nitric oxide (NO) formation (L-arginine analogue), as well as islet culture, nitrite assay and ultrastructural studies were performed. Results showed that Ia-b and ICAM-1 immunoreactivities on endothelia are a very early phenomenon and that pancreatic blood vessels and, in particular, some peri-islet venules, as well as several venules of the exocrine parenchyma, undergo significant morphological changes. Several endothelial cells of both peri-islet and extra-islet compartments, often showed Ia-b and ICAM-1 immunoreactivities, demonstrating that these cells are important for the adhesion processes taking place during early autoimmune inflammation. Inhibition of NO formation does not significantly affect ICAM-1 and Ia-b immunoreactivity both in vivo and in vitro, BM8 immunoreactive cells were considerably less in number although these were detected either around islets or along pancreatic septa, but rarely within the epithelial layer.

The rôle of copper level in the formation of neuronal lipofuscin in the spinal ganglia of Torpedo m

Abstract Copper, a marine pollutant of the Gulf of Naples, appears to be involved in the formation of lipofuscin in neuronal cells of Torpedo m. Lipofuscin pigment, a wear and tear pigment, is considered to be a marker of cell damage—in particular in cells such as neurons which are post-mitotic cells which reveal the life history of an an individual. Samples of Torpedo m. were collected from two sites with different levels of pollution. Other animals were kept for 60 days in a closed circuit seawater tank enriched with CuCl2. In addition to cells of the central nervous system (CNS), other organs were sampled for copper content. Detailed quantification of lipofuscin was made, at the electronmicroscopic level, of spinal ganglia cells and cells of the electric lobe, revealing the high content of lipofuscin in the spinal ganglia neurons of fish from a heavily polluted area and a further increase of lipofuscin in those neurons of animals kept in artificially high copper-containing seawater. The general implications of this pollution for the Gulf of Naples are discussed.

The effect of copper pollution on mitochondrial degeneration

Abstract The authors describe the effect of copper pollution on the mitochondria from various areas of the Torpedo marmorata central nervous system. A high percentage of swollen mitochondria has been observed in neurons from animals experimentally exposed to high level of copper (4 ppm). The correlation with age pigment granules is discussed.

Superoxide dismutase in the nonobese diabetic (NOD) mouse: A dynamic time-course study

Superoxide dismutase (SOD) levels, thought to be the first cellular defence against free radicals, were studied in the nonobese diabetesprone (NOD-p) mouse, an animal model of type 1 diabetes in which about 100% of females and 20% of males become diabetic. Nonobese diabetes nonprone (NON-p) mice were used as controls. Animals were followed from 5th to 22nd week of life. Results show that SOD levels in female NOD-p mice are extremely low. In males, values are considerably higher than in females but still lower than values found in control mice. Moreover, SOD levels did not significantly change with age, degree of insulitis or level of diabetes. Islet beta cells in this strain, therefore, seem to be poorly protected against the negative effects of free radicals and this may predispose to diabetes. Furthermore, alterations of SOD may not be directly related to the development of the disease as the enzymes activity is not further modified with age or the progression of diabetes.

Influence of environmental stress on lipofuscin production

The Corollospora maritima, a marine ascomycete, has been used as an experimental model to investigate the possibility that age pigments can be considered indicators also of environmental stress. Synthetic sea water enriched with iron or copper has been inoculated in a broth culture of the fungus. After 5 days of incubation the mycetes were assayed for lipofuscin fluorescent pigment and malondialdehyde content. The presence in the culture medium of the heavy metal ions results in an increase of the lipofuscin and malondialdehyde production. The same evidence has been obtained with sea water samples collected at seven sites along the coast of the Gulf of Naples (Italy): the lipofuscin and malondialdehyde production increases proportionally with the copper and iron pollution in the sea water.

Macrophages and antioxidant status in the NOD mouse pancreas

This study showed that citiolone (CIT), a free radical scavenger, significantly increased superoxide dismutase (P < 0.001 vs. untreated NOD, NMMA‐treated, and silica‐treated animals), catalase (P < 0.01 vs. untreated NOD), and glutathione peroxidase (P < 0.001 vs. untreated NOD and C57BL6/J) values. Silica treatment was capable of counteracting the plasma antioxidant capacity (TRAP) decrease observed in untreated NOD mice, although it did not block the blood glucose rise and insulitis progression in type 1 diabetes significantly. Conversely, early silica administration was able to deplete macrophages (as demonstrated by immunocytochemistry) and to block the rise in blood glucose levels and insulitis progression significantly. Silica‐treated animals in this study showed the highest TRAP levels, demonstrating that depletion of macrophages also was able to improve the antioxidant status. This study suggested that macrophages are essential for type 1 diabetes development and showed that they also are involved when the antioxidant status is affected. The reported findings are significant in view of previous studies indicating that oxygen and/or nitrogen free radicals contribute to the islet β‐cell destruction in type 1 diabetes animal models. J. Cell. Biochem. 71:479–490, 1998.

The vitamin-E derivative U-83836-E in the low-dose streptozocin-treated mouse: effects on diabetes development

Low-dose streptozocin-treated (LDS) mice were administered an inhibitor of lipid peroxidation, U-83836-E (a derivative of vitamin E), in order to observe its ability to alter the onset of diabetes. Ten or 20 mg/kg body wt. per day of U-83836-E were given to mice for 7 days and they were killed after 21 days. Results revealed that there was a significant increase in glycaemia in treated groups up to day 14 after which no further increase was noticed. Superoxide dismutase (SOD) assay showed that: (1) the LDS treatment significantly reduces SOD activity when compared with untreated controls (P < 0.005); (2) U-83836-E increases SOD levels (when compared with untreated controls); and (3) U-83836-E counteracts LDS treatment, since SOD activity is significantly higher with respect to that found in LDS-controls (P < 0.05), and SOD levels were significantly higher with respect to that found in Group 2 animals (P < 0.05), but significantly lower with respect to those found in groups 3 and 4 (P < 0.005). Moreover, malondialdehyde (MDA), the end-product of lipoperoxidation, was found at much higher levels in LDS controls than in the other groups and the lowest values were found in U-83836-E controls and in normoglycaemic animals treated with both streptozocin and U-83836-E. Morphological observations demonstrated that islet beta cells were of normal appearance in normoglycaemic animals of the treated groups. In conclusion, the in vivo inhibition of lipid peroxidation by this compound produces a limited but significant prevention of the islet beta cell destruction.