Search results for "Reactive nitrogen species"

The chemistry of melatonin's interaction with reactive species

2002

Melatonin has been shown to be an effective antioxidant in a number of experimental models both in vitro and in vivo. Considering the data available, it is now clear that the indoleamine is involved in antioxidative mechanisms more complex than originally envisaged. These range from the direct radical scavenging of a variety of radicals and reactive species to the control and/or modulation of a number of processes which may trigger a redox imbalance between antioxidant and prooxidant species. This review focuses on the direct radical scavenging activity of melatonin and provides a summary of the mechanisms of the reactions between the indoleamine and reactive species in pure chemical soluti…

Oxidative stress in osteoarticular diseases

2016

Role of Nitric Oxide for Modulation of Cancer Therapy Resistance

2010

Reactive nitrogen species (RNS) act as central second messengers in a balanced cellular network. While the complexity of nitric oxide (NO) signaling is far from being understood, and many controversial data can be found in the literature, there is evidence for NO as a major player of modulation of resistance to anticancer drugs and radiotherapy. Hypoxia in cancer tissues causes therapy resistance, and the hypoxia-inducing factor-1 (HIF-1) plays a predominant role in hypoxia-induced resistance. NO and NO-donating compounds sensitize tumor cells by inhibiting HIF-1 mediated transcription in hypoxic cells. Among a plethora of other genes, HIF-1-induced the transcription of the multidrug resist…

Metabolism via arginase or nitric oxide synthase: two competing arginine pathways in macrophages

2014

Macrophages play a major role in the immune system, both as antimicrobial effector cells and as immunoregulatory cells, which induce, suppress or modulate adaptive immune responses. These key aspects of macrophage biology are fundamentally driven by the phenotype of macrophage arginine metabolism that is prevalent in an evolving or ongoing immune response. M1 macrophages express the enzyme nitric oxide synthase (NOS), which metabolizes arginine to nitric oxide (NO) and citrulline. NO can be metabolized to further downstream reactive nitrogen species, while citrulline might be reused for efficient NO synthesis via the citrulline-NO cycle. M2 macrophages are characterized by expression of the…

Diabetes, oxidative stress and therapeutic strategies.

2014

Abstract Background Diabetes has emerged as a major threat to health worldwide. Scope of Review The exact mechanisms underlying the disease are unknown; however, there is growing evidence that excess generation of reactive oxygen species (ROS), largely due to hyperglycemia, causes oxidative stress in a variety of tissues. Oxidative stress results from either an increase in free radical production, or a decrease in endogenous antioxidant defenses, or both. ROS and reactive nitrogen species (RNS) are products of cellular metabolism and are well recognized for their dual role as both deleterious and beneficial species. In type 2 diabetic patients, oxidative stress is closely associated with ch…

Is oxidative stress a therapeutic target in cardiovascular disease?

2010

An abnormal production of reactive oxygen species (ROS) and the subsequent decrease in vascular bioavailability of nitric oxide (NO) have long been proposed to be the common pathogenetic mechanism of the endothelial dysfunction, resulting from diverse cardiovascular risk factors such as hypercholesterolaemia, diabetes mellitus, chronic smoking, metabolic syndrome, and hypertension. Superoxide produced by the nicotinamide dinucleotide phosphate (NADPH) oxidase, mitochondrial sources, or the xanthine oxidase may react with NO, thereby resulting in excessive formation of peroxynitrite, a reactive nitrogen species that has been demonstrated to accelerate the atherosclerotic process by causing d…

Oxidative and nitrosative stress in the metastatic microenvironment.

2010

Metastases that are resistant to conventional therapies are the main cause of most cancer-related deaths in humans. Tumor cell heterogeneity, which associates with genomic and phenotypic instability, represents a major problem for cancer therapy. Additional factors, such as the attack of immune cells or organ-specific microenvironments, also influence metastatic cell behavior and the response to therapy. Interaction of cancer and endothelial cells in capillary beds, involving mechanical contact and transient adhesion, is a critical step in the initiation of metastasis. This interaction initiates a cascade of activation pathways that involves cytokines, growth factors, bioactive lipids and r…