@entity191 occurs in 1% of @entity1 over the age of 65 when about 60% of the dopaminergic neurons in the substantia nigra of the midbrain are lost. Dopaminergic neurons appear to die by a process of apoptosis that is induced by oxidative stress. @entity26 radicals abstract @entity3884 from DNA forming DNA radicals that lead to DNA fragmentation, activation of DNA protective mechanisms, @entity2125 depletion and apoptosis. @entity26 radicals can be formed in dopaminergic neurons by redox cycling of MPP+, the active metabolite of @entity5212 . This redox cycling mechanism involves the reduction of MPP+ by a number of enzymes, especially @entity1785 containing enzymes, some of which are found in mitochondria. @entity669 hydroxylase is present in all dopaminergic neurons and is responsible for the synthesis of @entity935 . However, @entity669 hydroxylase can form @entity26 radicals in a redox mechanism involving its cofactor, @entity8083 . @entity935 may be oxidized by @entity1154 oxidase to form @entity26 radicals and @entity6859 . This @entity264 may be oxidized by @entity264 dehydrogenase with the formation of @entity26 radicals and @entity4925 . The redox mechanisms of @entity26 radical formation by @entity5212 , @entity669 hydroxylase, @entity1154 oxidase and @entity264 dehydrogenase will be discussed. Possible clinical applications of these mechanisms will be briefly presented.

XXXX --redox mechanisms.

@entity1 :: ('9606', 'Species') :: ['people'] @entity2125 :: ('MESH:D009243', 'Chemical') :: ['NAD'] @entity5212 :: ('MESH:D015632', 'Chemical') :: ['MPTP'] @entity3884 :: ('MESH:D006859', 'Chemical') :: ['hydrogen'] @entity1785 :: ('MESH:C024132', 'Chemical') :: ['flavin'] @entity8083 :: ('MESH:C003402', 'Chemical') :: ['tetrahydrobiopterin'] @entity935 :: ('MESH:D004298', 'Chemical') :: ['Dopamine', 'dopamine'] @entity4925 :: ('MESH:D015102', 'Chemical') :: ['3,4-dihydroxyphenylacetic acid'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen', 'Oxygen'] @entity191 :: ('MESH:D010300', 'Disease') :: ["Parkinson's disease"] @entity6859 :: ('MESH:C007430', 'Chemical') :: ['3,4-dihydroxyphenylacetaldehyde'] @entity1154 :: ('CHEBI:25375', 'Chemical') :: ['monoamine'] @entity669 :: ('CHEBI:18186', 'Chemical') :: ['Tyrosine', 'tyrosine'] @entity264 :: ('CHEBI:17478', 'Chemical') :: ['aldehyde']
@entity191 :: (MESH:D010300,Disease) :: ['Parkinson's disease']
