Liver nuclear NADPH-cytochrome P-450 reductase may be involved in redox cycling of bleomycin-Fe(III), oxy radical formation and DNA damage

Antioxidants as potential therapeutics for lung fibrosis

Interstitial lung disease encompasses a large group of chronic lung disorders associated with excessive tissue remodeling, scarring, and fibrosis. The evidence of a redox imbalance in lung fibrosis is substantial, and the rationale for testing antioxidants as potential new therapeutics for lung fibrosis is appealing. Current animal models of lung fibrosis have clear involvement of ROS in their pathogenesis. New classes of antioxidant agents divided into catalytic antioxidant mimetics and antioxidant scavengers are being developed. The catalytic antioxidant class is based on endogenous antioxidant enzymes and includes the manganese-containing macrocyclics, porphyrins, salens, and the non-metal-containing nitroxides. The antioxidant scavenging class is based on endogenous antioxidant molecules and includes the vitamin E analogues, thiols, lazaroids, and polyphenolic agents. Numerous studies have shown oxidative stress to be associated with many interstitial lung diseases and that these agents are effective in attenuating fibroproliferative responses in the lung of animals and humans.

Role of oxidative stress in cardiovascular diseases

OBJECTIVES

In view of the critical role of intracellular Ca2 overload in the genesis of myocyte dysfunction and the ability of reactive oxygen species (ROS) to induce the intracellular Ca2+-overload, this article is concerned with analysis of the existing literature with respect to the role of oxidative stress in different types of cardiovascular diseases.

OBSERVATIONS

Oxidative stress in cardiac and vascular myocytes describes the injury caused to cells resulting from increased formation of ROS and/or decreased antioxidant reserve. The increase in the generation of ROS seems to be due to impaired mitochondrial reduction of molecular oxygen, secretion of ROS by white blood cells, endothelial dysfunction, auto-oxidation of catecholamines, as well as exposure to radiation or air pollution. On the other hand, depression in the antioxidant reserve, which serves as a defense mechanism in cardiac and vascular myocytes, appears to be due to the exhaustion and/or changes in gene expression. The deleterious effects of ROS are mainly due to abilities of ROS to produce changes in subcellular organelles, and induce intracellular Ca2+-overload. Although the cause-effect relationship of oxidative stress with any of the cardiovascular diseases still remains to be established, increased formation of ROS indicating the presence of oxidative stress has been observed in a wide variety of experimental and clinical conditions. Furthermore, antioxidant therapy has been shown to exert beneficial effects in hypertension, atherosclerosis, ischemic heart disease, cardiomyopathies and congestive heart failure.

CONCLUSIONS

The existing evidence support the view that oxidative stress may play a crucial role in cardiac and vascular abnormalities in different types of cardiovascular diseases and that the antioxidant therapy may prove beneficial in combating these problems.

Conjugation of bleomycin with concanavalin A or immunoglobulin G increases its ability to destroy cell membranes

Hybrid molecules consisting of an address peptide and an active oxygen-generating fragment may be used for selective destruction of cells. We tested the possibility of using the antibiotic bleomycin (BLM) as an active oxygen-generating fragment of such a molecule. It was found that bleomycin can induce destruction of cell membranes. BLM-mediated cell destruction was inhibited by addition of catalase, superoxide dismutase, and OH. scavangers (mannitol and ethanol), suggesting that hydroxy radical is involved in the process. BLM can induce membrane impairment at the expense of electrons supplied by NADPH-cytochrome P450 reductase. Covalent binding of BLM to an address fragment (concanavalin A, immunoglobulin G) increases the ability of BLM to destroy erythrocyte membranes. The data obtained lead to the conclusion that BLM can be used as an active oxygen-generating fragment of a proposed cell-destroying hybrid molecule.