Các chất chuyển hóa phản ứng bao gồm các nhóm khác nhau như epoxit, quinon, các gốc tự do, các loài ôxy phản ứng, và các hợp chất không ổn định. Hình đưa ra một số ví dụ Với một số hóa chất chỉ có một phản ứng enzyme có liên quan, trong khi đó với các hợp chất khác, nhiều phản ứng, | TYPES OF LIVER INJURY 267 accumulation of fibrous material causes severe restriction in blood flow and in the liver s normal metabolic and detoxication processes. This situation can in turn cause further damage and eventually lead to liver failure. In humans chronic use of ethanol is the single most important cause of cirrhosis although there is some dispute as to whether the effect is due to ethanol alone or is also related to the nutritional deficiencies that usually accompany alcoholism. Hepatitis Hepatitis is an inflammation of the liver and is usually viral in origin however certain chemicals usually drugs can induce a hepatitis that closely resembles that produced by viral infections Table . This type of liver injury is not usually demonstrable in laboratory animals and is often manifest only in susceptible individuals. Fortunately the incidence of this type of disease is very low. Oxidative Stress Oxidative stress has been defined as an imbalance between the prooxidant antioxidant steady state in the cell with the excess of prooxidants being available to interact with cellular macromolecules to cause damage to the cell often resulting in cell death. Although the occurrence of reactive oxygen species in normal metabolism and the concept of oxidative stress was derived from these studies it is apparent that oxidative stress can occur in almost any tissue producing a variety of deleterious effects. To date a number of liver diseases including alcoholic liver disease metal storage diseases and cholestatic liver disease have been shown to have an oxidative stress component. Reactive oxygen and reactive nitrogen radicals can be formed in a number of ways Figure the former primarily as a by-product of mitochondrial electron transport. Superoxide hydrogen peroxide singlet oxygen and hydroxyl can all arise from this source. Other sources include monooxygenases and peroxisomes. If not detoxified reactive oxygen species can interact with .
