Hyperoxia occurs when cells, tissues and organs are exposed to an excess supply of oxygen (O2) or  higher than normal partial pressure of oxygen.In medicine, it refers to excess oxygen in the lungs or other body tissues, which can be caused by breathing air or oxygen at pressures greater than normal atmospheric pressure. This kind of hyperoxia can lead to oxygen toxicity, caused from the harmful effects of breathing molecular oxygen at elevated partial pressures. Hyperoxia is the opposite of hypoxia; hyperoxia refers to a state in which oxygen supply is excessive, and hypoxia refers to a state in which oxygen supply is insufficient. In the environment, it refers to excess oxygen in a body of water or other habitat. Signs and symptoms
Associated with hyperoxia is an increased level of reactive oxygen species (ROS), which are chemically reactive molecules containing oxygen. These oxygen containing molecules can damage lipids, proteins, and nucleic acids, and react with surrounding biological tissues. The human body has naturally occurring antioxidants to combat reactive molecules, but the protective antioxidant defenses can become depleted by abundant reactive oxygen species, resulting in oxidation of the tissues and organs.The symptoms produced from breathing high concentrations of oxygen for extended periods have been studied in a variety of animals, such as frogs, turtles, pigeons, mice, rats, guinea pigs, cats, dogs and monkeys. The majority of these studies reported the occurrence of irritation, congestion and edema of the lungs, and even death following prolonged exposures.
The vestibular portion of cranial nerve VIII (the vestibulocochlear nerve) can be affected, resulting in tinnitus, vertigo, ataxia, kidney toxicity, and can potentially interfere with diagnosis of kidney malfunction.Common side effects include vertigo, vomiting, numbness of the face, fever, and rash. Fever and rashes may result from persistent use.Use is not recommended during pregnancy. Congenital deafness has been reported in children whose mothers received streptomycin during pregnancy. Use appears to be okay while breastfeeding.It is not recommended in people with myasthenia gravis. Mechanism of action
Streptomycin functions as a protein synthesis inhibitor. It binds to the small 16S rRNA of the 30S ribosomal subunit irreversibly, interfering with the binding of formyl-methionyl-tRNA to the 30S subunit. This causes codon misreading, inhibition of protein synthesis, and ultimately death of the cell through mechanisms that are not well understood. Speculation indicates that the binding of the molecule to the 30S subunit interferes with 30S subunit association with the mRNA strand. This results in an unstable ribosomal-mRNA complex, leading to premature stopping of protein synthesis, leading to cell death. As human and bacteria both have ribosomes, streptomycin has significant side effects in humans. At low concentrations, however, streptomycin inhibits only bacterial growth.Streptomycin is an antibiotic that inhibits both Gram-positive and Gram-negative bacteria, and is therefore a useful broad-spectrum antibiotic.