Antioxidants protect against glutamate-induced cytotoxicity in a neuronal cell line.

The effects of reducing agents and antioxidants on L-Glutamate (Glu)-induced cytotoxicity were examined in the N18-RE-105 neuronal cell line. The cytotoxicity by Glu (1 and 10mM) was potentiated by exposure to growth medium containing a low concentration of cystine (5-100 microM), instead of the normal medium containing 200 microM cystine. In contrast, the toxicity was suppressed by increasing the cystine concentration to 500 to 1000 microM. Reducing agents, cysteine (30-1000 microM), dithiothreitol (10-250 microM) and glutathione (GSH, 10-1000 microM) also protected the cells against the cytotoxicity of 10 mM Glu in a concentration-dependent manner. The antioxidants vitamin E (10-100 microM), idebenone (0.1-3 microM) and vinpocetine (10-100 microM) also provided marked protection against the cytotoxicity of Glu (10 mM) or quisqualate (1 mM). Antioxidants also prevented the delayed cell death caused by lowering the concentration of cystine in the medium to 5 microM. Incubation of the cells with 10 mM Glu caused a marked decrease in cellular GSH levels. Although cysteine and dithiothreitol prevented the GSH reduction caused by Glu, antioxidants did not. The cellular levels of oxidants were assessed using 2,7-dichlorofluorescin, a probe that accumulates within cells and is converted to a fluorescent product by oxidation. Glu (10 mM) caused a marked increase in such fluorescence, whereas vitamin E and idebenone reduced markedly the number of fluorescent cells to control levels even added with 10 mM Glu. These results indicate that oxidative stress due to loss of cellular levels of GSH is one mechanism whereby Glu/quisqualate exert cytotoxicity and suggest that centrally active antioxidants may reduce neuronal damage in pathologic conditions associated with excessive Glu release.

In vitro effects of prostaglandin E1, prostaglandin E2, indomethacin, histamine, and tuftsin on chemiluminescence response of bovine polymorphonuclear leukocytes.

The in vitro effects of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), indomethacin, histamine, and tuftsin on the chemiluminescence response of bovine polymorphonuclear cells (PMN) were determined. Addition of PGE1, PGE2, indomethacin, and histamine in vitro significantly suppressed the chemiluminescence response of bovine PMN's, whereas tuftsin had no effect. Suppression was dependent upon the continued presence of PGE1, PGE2, and histamine in the culture media. However, indomethacin's suppressive effect remained even after it was removed from the culture media. Hydrogen peroxide generated chemiluminescence was suppressed by high concentrations of indomethacin and histamine. Results of this study suggest possible pharmacologic or regulatory mechanisms for certain of these immune modulators in the control of the oxidative burst reaction of bovine PMN's.

Immunological and ultrastructural aspects of the cell-mediated killing of Dirofilaria immitis microfilariae.

Neutrophils in the presence of serum from dogs with occult Dirofilaria immitis infections were shown to be cytotoxic to D. immitis microfilariae recovered from the blood of microfilaraemic dogs. This cytotoxicity was correlated with the presence of IgM and IgG antibodies on the cuticular surface of microfilariae incubated in the sera from occult dogs. Such antibodies were not observed on the surface of microfilariae incubated in sera from microfilaraemic or normal dogs. The neutrophil attack was directed at the cuticular crypts, at which sites the worms appeared to be structurally most vulnerable because of the absence of the outer layer of the cuticle. The IgM antibodies were shown to be bound preferentially to these sites. Our data suggested that the neutrophil-mediated toxicity involved both hydrogen peroxide release and degranulation.

[Physiological and pathophysiological significance of superoxide-radicals and the regulatory role of the enzyme superoxide dismutase (author's transl)]. / Physiologische und pathophysiologische Bedeutung von Superoxid-Radikalen und die regulatorische Rolle des Enzyms Superoxiddismutase.

The monovalent reduction of molecular oxygen, resulting in the formation of superoxide radicals (O(2)) is regarded as to be an ongoing physiological process involved in the respiration and other biological processes of aerobic cells. These reactive oxygen species have been reported to function as cofactors in many biosynthetic reaction steps. Thus, deviations from cellular steady state concentrations may lead to a multiplicity of clinical symptoms or may to a great deal determine the characteristic of a distinct malady. Decrease of cellular O(2)-concentration is discussed in connection with Trisomie 21 and various mental disorders. The role of O(2) in the biochemistry of inflammation, autoimmune diseases, various toxicological cases and the biological aging process is described. Hypothetical considerations concerning the involvement of O(2) in the pathogenetic mechanisms of Morbus Wilson, haemochromatosis, Parkinson syndrome, cataractogenesis and in carcinogenesis are presented. The physiological control of cellular O(2)-concentration is performed by formation rates of the various cellular O(2)-sources and the overall elimination rates of O(2)-consuming reaction steps. Superoxide dismutase (SOD) is of special interest within this cycle because it detoxifies O(2) radicals with velocity rates which are significantly faster than any other pathway involved in O(2) elimination. Thus attempts for a therapeutic interference on tissue levels of O(2)-radicals are mainly based on inhibition or activation of cellular SOD-activities depending on a supposed decrease or increase in cellular steady state concentrations of O(2). The availability of a drug version of SOD and of various synthetic SOD-active compounds allowing a therapeutic decrease of O(2)-tissue levels. Inhibition of cellular SOD is also possible, however, many still unknown toxic side effects should be expected because of unspecific action of the inhibitor available.