Oxidative Stress and Antioxidant Defenses: With Special Reference to Oral Lesions

Background: Oxidative stress is involved in the pathogenesis of various lifestyle-related diseases, including malignancies. The body naturally produces antioxidants as a means of defending itself against these free radicals which neutralize them, thereby rendering them harmless to other cells. There is a close relation between oxidative stress and all aspects of cancer, from carcinogenesis to the tumor-bearing state, from treatment to its prevention. Aim: The present study was aimed to estimate the plasma levels of antioxidant enzymes and molecules in cases of oral lesion patients. Study Design and Methodology: A case control study was designed in Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow campus. A total of fifty histopathologically proven oral lesion cases (leukoplakia, erythroplakia, lichen planus and oral submucous fibrosis patients) were taken for the study. Their blood samples were collected and plasma was subjected to evaluation of oxidative stress markers. Control group consisted of equal number of healthy subjects. The data is expressed as mean±SD. Student -t test was applied for significance of the biochemical parameters. Results: The results have demonstrated that levels of catalase, myeloperoxidase, reduced glutathione glutathione reductase and glutathione peroxidase are decreased whereas those of malondialdehyde and nitric oxide have increased in the oral lesions patient group as compared to controls. Conclusion: Oxidative stress has been shown to be an important indicator in case of oral cancer. Similar findings in pre-malignant oral lesions can be correlated in establishing the role of oxidative stress in initiation and conversion of premalignant lesions into malignant ones.

Nitric oxide and immune response.

Nitric oxide (NO), initially described as a physiological mediator of endothelial cell relaxation plays an important role in hypotension. It is an intercellular messenger and has been recognized as one of the most versatile players in the immune system. Cells of the innate immune system--macrophages, neutrophils and natural killer (NK) cells use pattern recognition receptors to recognize molecular patterns associated with pathogens. Activated macrophages then inhibit pathogen replication by releasing a variety of effector molecules, including NO. In addition to macrophages, a large number of other immune system cells produce and respond to NO. Thus, NO is important as a toxic defense molecule against infectious organisms. It also regulates the functional activity, growth and death of many immune and inflammatory cell types including macrophages, T lymphocytes, antigen-presenting cells, mast cells, neutrophils and NK cells. However, the role of NO in non-specific and specific immunity in vivo and in immunologically mediated diseases and inflammation is poorly understood. This review discusses the role of NO in immune response and inflammation and its mechanisms of action in these processes.

Gene therapy in ocular diseases.

Gene therapy is a novel form of drug delivery that enlists the synthetic machinery of the patient's cells to produce a therapeutic agent. Genes may be delivered into cells in vitro or in vivo utilising viral or non-viral vectors. Recent technical advances have led to the demonstration of the molecular basis of various ocular diseases. Ocular disorders with the greatest potential for benefit of gene therapy include hereditary diseases such as retinitis pigmentosa, tumours such as retinoblastoma or melanoma, and acquired proliferative and neovascular retinal disorders. Gene transfer into ocular tissues has been demonstrated with growing functional success and may develop into a new therapeutic tool for clinical ophthalmology in future.