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To address whether diabetes enhances lipid peroxidation and attenuates nitric oxide (NO) generation resulting in tissue complications, we measured oxysterols and NO metabolites (NOx) in the tissues of diabetic Wistar rats. After 4 weeks of streptozotocin injection (STZ, 80 mg/kg, i.p.), we measured 7 alpha- and 7 beta-hydroperoxycholest-5-en-3 beta-ol (7 alpha-OOH and 7 beta-OOH), 7 alpha- and 7 beta-hydroxycholesterol (7 alpha-OH and 7 beta-OH) and 7-ketocholesterol (7-keto) by HPLC in the kidneys, heart, and liver. All the oxysterols were much higher in the diabetic than in sham rats, while the extent of the increase was higher in the order of the kidney, heart, and liver. Together with high blood urea nitrogen, the data indicate that the kidney is the predominant target of early diabetic complications. Plasma NOx were decreased by 20% in the STZ rats. The enhanced oxidative stress in diabetes would increase oxysterols by peroxidation, while superoxide is known to reduce NO by reaction to form another potent oxidant peroxynitrite.

Excessive alcohol ingestion is damaging and gives rise to a number of pathologies that influence nutritional status. Most organs of the body are affected such as the liver and gastrointestinal tract. However, skeletal muscle appears to be particularly susceptible, giving rise to the disease entity alcoholic myopathy. Alcoholic myopathy is far more common than overt liver disease such as cirrhosis or gastrointestinal tract pathologies. Alcohol myopathy is characterised by selective atrophy of Type II (anaerobic, white glycolic) muscle fibres: Type I (aerobic, red oxidative) muscle fibres are relatively protected. Affected patients have marked reductions in muscle mass and impaired muscle strength with subjective symptoms of cramps, myalgia and difficulty in gait. This affects 40-60% of chronic alcoholics (in contrast to cirrhosis, which only affects 15-20% of chronic alcohol misuers).Many, if not all, of these features of alcoholic myopathy can be reproduced in experimental animals, which are used to elucidate the pathological mechanisms responsible for the disease. However, membrane changes within these muscles are difficult to discern even under the normal light and electron microscope. Instead attention has focused on biochemical and other functional studies. In this review, we provide evidence from these models to show that alcohol-induced defects in the membrane occur, including the formation of acetaldehyde protein adducts and increases in sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase (protein and enzyme activity). Concomitant increases in cholesterol hydroperoxides and oxysterol also arise, possibly reflecting free radical-mediated damage to the membrane. Overall, changes within muscle membranes may reflect, contribute to, or initiate the disturbances in muscle function or reductions in muscle mass seen in alcoholic myopathy. Present evidence suggest that the changes in alcoholic muscle disease are not due to dietary deficiencies but rather the direct effect of ethanol or its ensuing metabolites.

It is our hypothesis that as a consequence of increased oxidative stress, rats develop lung injury with increased cholesterol-derived hydroperoxides and oxysterols in lung after consecutive exposure of the rats to paraquat. To test this we administered 10 mg/kg of paraquat i.p. once or seven times (once a day) to Wistar rats. Rats were killed, and lung tissue was collected 24 h after the last paraquat injection. We found that in response to consecutive paraquat doses, there were significant increases in 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ol (7alpha-OOH and 7beta-OOH; P=0.01) as well as 7alpha- and 7beta-hydroxycholesterol (7alpha-OH and 7beta-OH; P=0.01), and 7-ketocholesterol (7-keto; P=0.03). In addition, pulmonary hemorrhage, thickening of alveolar septum, and inflammatory cell infiltration of macrophages were observed. This is the first report showing enhanced cholesterol peroxidation and lung injury of rats due to consecutive doses of paraquat.

The present study is undertaken to determine if ethanol affects 7-hydroperoxycholesterol or oxysterols in rat skeletal muscle after chronic ethanol feeding. Wistar rats were fed a liquid diet containing ethanol as 35% of total calories. After 6 weeks, soleus (Type I fibre-predominant) and plantaris (Type II fibre-predominant) skeletal muscles were dissected out. We measured 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ol (7alpha-OOH and 7beta-OOH) as well as 7alpha- and 7beta-hydroxycholesterol (7alpha-OH and 7beta-OH) and 3beta-hydroxycholest-5-en-7-one (7-keto). We found that in response to chronic alcohol feeding, there were significant increases in soleus 7alpha-OH (P=0.0005), 7beta-OH (P=0.0005) and 7-keto (P=0.0007), but in the plantaris, 7beta-OH increased (P=0.0418). Their elevation in chronic experimental alcoholism, together with increases in cholesterol hydroperoxides, may possibly represent evidence of increased oxidative stress.

It was our hypothesis that, as a consequence of increased oxidative stress, cholesterol-derived hydroperoxides and oxysterols are increased in livers of rats exposed to ethanol. To test this we dosed Wistar rats (approximately 0.1 kg initial body weight) with ethanol chronically (rats fed a nutritionally complete liquid diet containing ethanol as 35% of total calories; sampled liver at approximately 6-7 weeks). We measured concentrations of 7 alpha- and 7 beta-hydroperoxycholest-5-en-3 beta-ol (7 alpha-OOH and 7 beta-OOH) as well as 7 alpha- and 7 beta-hydroxycholesterol (7 alpha-OH and 7 beta-OH), and 3 beta-hydroxycholest-5-en-7-one (also termed 7-ketocholesterol; 7-keto). In response to chronic alcohol feeding, there were significant elevations in the concentrations of 7 alpha-OOH (+169%, P = 0.005) and 7 beta-OOH (+199%, P = 0.011). Increases in the concentrations of hepatic 7-keto (+74%, P = 0.01) and decreases in cholesterol (-43%; P = 0.03) also occurred. In contrast, the concentrations of both 7 alpha-OH and 7 beta-OH were not significant (NS). However, when oxysterols in chronic ethanol-fed rats were expressed relative to cholesterol there were significant increases in 7-keto/cholesterol (P = 0.0006), 7 alpha-OH/cholesterol (P = 0.0018) and 7 beta-OH/cholesterol (P = 0.0047). In conclusion, this is the first report of increased 7 alpha-OOH, 7 beta-OOH, and 7-keto in liver of rats and their elevation in chronic experimental alcoholism represent evidence of increased oxidative stress.

It was our hypothesis that, as a consequence of increased oxidative stress, cholesterol-derived hydroperoxides and oxysterols are increased in skeletal muscles chronically exposed to ethanol. To test this we fed male Wistar rats (0.1 kg initial body weight) a nutritionally complete liquid diet containing ethanol as 35% of total calories: controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. At the end of 1(1/2) months, soleus (type I fiber-predominant) and plantaris (type II fiber-predominant) skeletal muscles were dissected out. We measured 7 alpha- and 7 beta-hydroperoxycholest-5-en-3 beta-ol (7 alpha-OOH and 7 beta-OOH), as well as 7 alpha- and 7 beta-hydroxycholesterol (7 alpha-OH and 7 beta-OH), and 3 beta-hydroxycholest-5-en-7-one (also termed 7-ketocholesterol; 7-keto). We identified and confirmed by LC-MS the presence of 7 alpha-OOH, 7 beta-OOH and 7 alpha-OH, 7 beta-OH and 7-keto in skeletal muscle of rats. We also showed that in response to chronic alcohol feeding, there were significant increases in soleus 7 alpha-OH (P =.0005), 7 beta-OH (P =.0005), and 7-keto (P =.0007). In the plantaris, mean 7 alpha-OH and 7-keto were not significantly altered (P >.05), but 7 beta-OH increased (P =.0418). This is the first report of 7 alpha-OH, 7 beta-OH, and 7-keto oxysterols being identified in skeletal muscle of rats. Their elevation in chronic experimental alcoholism, together with increases in cholesterol hydroperoxides, may possibly represent evidence of increased oxidative stress., (Copyright 2002, Elsevier Science (USA). All rights reserved.)

Chronic alcoholic myopathy affects up to two-thirds of all alcohol misusers and is characterized by selective atrophy of Type II (glycolytic, fast-twitch, anaerobic) fibers. In contrast, the Type I fibers (oxidative, slow-twitch, aerobic) are relatively protected. Alcohol increases the concentration of cholesterol hydroperoxides and malondialdehyde-protein adducts, though protein-carbonyl concentration levels do not appear to be overtly increased and may actually decrease in some studies. In alcoholics, plasma concentrations of alpha-tocopherol may be reduced in myopathic patients. However, alpha-tocopherol supplementation has failed to prevent either the loss of skeletal muscle protein or the reductions in protein synthesis in alcohol-dosed animals. The evidence for increased oxidative stress in alcohol-exposed skeletal muscle is thus inconsistent. Further work into the role of ROS in alcoholic myopathy is clearly warranted.

The aim of this study is to evaluate oxidative stress in man after paraquat ingestion by analyzing 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ol (7alpha- and 7beta-OOH) as well as oxysterols, cholesterol oxidation products, as indices of lipid peroxidation. Lung, kidney, and liver were collected at autopsy from seven patients with paraquat poisoning and seven controls matched for age and sex. We identified for the first time 7-ketocholesterol (7-keto) and 7-hydroxycholesterol (7alpha-OH and 7beta-OH) in human kidney by LC-MS. Next, we quantified 7alpha-OOH and 7beta-OOH by HPLC with postcolumn chemiluminescence as well as oxysterols by HPLC-UV. Both 7alpha-OOH and 7beta-OOH detected in lung and kidney from the controls were as low as the paraquat group. In contrast, we found both 7-keto and 7beta-OH in lung and 7-keto in kidney from the paraquat group were significantly higher than from the controls. This is the first report on accumulated oxysterols in lung and kidney from human paraquat poisoning. It seems to reflect greater oxidative stress in the pathology of paraquat intoxication.

It was our hypothesis that, as a consequence of increased oxidative stress, cholesterol-derived hydroperoxides and oxysterols are increased in livers of rats exposed to ethanol. To test this we dosed Wistar rats (approximately 0.1 kg initial body weight) with ethanol chronically (rats fed a nutritionally complete liquid diet containing ethanol as 35% of total calories; sampled liver at approximately 6-7 weeks). We measured concentrations of 7α- and 7β-hydroperoxycholest-5-en-3β-ol (7α-OOH and 7β-OOH) as well as 7α- and 7β-hydroxycholesterol (7α-OH and 7β-OH), and 3β-hydroxycholest-5-en-7-one (also termed 7-ketocholesterol; 7-keto). In response to chronic alcohol feeding, there were significant elevations in the concentrations of 7α-OOH (+169%, P =0.005 ) and 7β-OOH (+199%, P =0.011 ). Increases in the concentrations of hepatic 7-keto (+74%, P =0.01 ) and decreases in cholesterol (-43%; P =0.03 ) also occurred. In contrast, the concentrations of both 7α-OH and 7β-OH were not significant (NS). However, when oxysterols in chronic ethanol-fed rats were expressed relative to cholesterol there were significant increases in 7-keto/cholesterol ( P =0.0006), 7α-OH/cholesterol ( P =0.0018) and 7β-OH/cholesterol ( P =0.0047). In conclusion, this is the first report of increased 7α-OOH, 7β-OOH, and 7-keto in liver of rats and their elevation in chronic experimental alcoholism represent evidence of increased oxidative stress. [ABSTRACT FROM AUTHOR]