Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functional versatility and diversity of melatonin has exceeded everyone's expectations. The evidence is substantial that melatonin has multiple receptor-mediated and receptor-independent actions. Considering the unexpectedly widespread distribution of cellular membrane receptors as well as the existence of nuclear binding sites/receptors and the fact that some of melatonin's actions are receptor-independent means that melatonin likely functions in every cell with which it comes in contact. This is highlighted by the fact that there are no morpho-physiological barriers to melatonin, e.g., the blood-brain barrier. In addition to its widespread actions, melatonin synthesis occurs in widely diverse tissues with its production not being relegated to the pineal gland. This should not be unexpected given that it is present throughout the animal kingdom including species that lack a pineal gland, e.g., insects, and in single cell organisms. In this review, only a few of melatonin's effects that involve the interaction of the indoleamine with receptors are described. These functions include the control of seasonal reproduction, modulation of sleep processes and influences on bone growth and osteoporosis. Among the actions of melatonin that are likely receptor independent and that are reviewed herein include its ability to neutralize free radicals which leads to a reduction in cataract formation, reducing oxidative stress due to exposure to hyperbaric hyperoxia, ameliorating hyperthyroidism and abating the toxicity of sepsis and septic shock. These actions alone speak to the diversity of beneficial effects of melatonin; however, the review is no way near exhaustive in terms of what melatonin is capable of doing. Because of its ubiquitous benefits, the pharmaceutical industry is developing melatonin analogues which interact with melatonin receptors. Clearly, the intent of the drugs is to take advantage of some of melatonin's numerous beneficial effects.
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PMID:Medical implications of melatonin: receptor-mediated and receptor-independent actions. 1821 86

The treatment of patients with hyperbaric oxygen (HBO), vitrectomy and loss of vitreous gel during aging is associated with a high risk of subsequent development of nuclear cataract. Many studies proved that oxidation is the key reason of nuclear cataract. Reactive oxygen species (ROS) are formed in mitochondria as a by-product of normal metabolism and as a consequence of exposure to environmental compounds. Therefore, mitochondrial DNA (mtDNA) is at particularly high risk of ROS-induced damage. Oxidative damage to mtDNA has been implicated as a causative factor in a wide variety of degenerative diseases and aging. However, the effect of mtDNA damage to the lens has not been studied. The goals of the study were to identify if there was increased mtDNA damage in lens when the eye were exposed to hyperoxic or hypoxic conditions and also to evaluate the changes in gene expression of mtDNA base excision repair (mtBER) enzymes. Our data have shown that the damage of mtDNA, the expression of mtBER enzymes and the level of 8-OHdG in lens increased after inspired hyperoxia, which is likely associated with oxidative stress. However, there was no effect to mtDNA and mtBER enzymes in lens after inspired hypoxia. Nuclear cataract appeared rapidly at 14 month old rats in hyperoxia group, and lens kept transparency in other groups.
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PMID:Oxygen-induced changes in mitochondrial DNA and DNA repair enzymes in aging rat lens. 2085 36

Age-related cataract and age-related macular degeneration (AMD) is the leading cause of vision impairment and blindness in developing and developed countries, respectively. Oxidative stress and oxidation products have been verified to play important roles in these two aging diseases. Recent research has demonstrated that there are significant oxygen gradients in the eye. Therefore, we propose a new hypothesis that these two diseases could be summarized as oxygen receptor dysfunction diseases of which the main points are as follows. Oxygen in the retinal and choroidal vasculature is transferred into the vitreous cavity by a special switching valve or oxygen receptor that might exist in the internal limiting membrane, vascular endothelium or posterior vitreous surface. It is then transported from the posterior segment to the anterior segment by vitreous collagen fibrilla networks, which work similar to a gas pipeline. Posterior vitreous detachment is the starting point of these two diseases by inducing formation of the local hyperoxia region, which results in the occurrence of age-related cataract and macular degeneration. Thus, an innovative anti-oxidative therapy should be added to the traditional treatment of age related macular degeneration. Some associated experimental and clinical approaches are suggested in our paper to test this hypothesis.
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PMID:Age-related cataract and macular degeneration: Oxygen receptor dysfunction diseases. 2604 22