Alcohol-inducible cytochrome P-450 (P-450 ALC )

Of the family of P-450 cytochromes occurring in rabbit liver microsomes, only isozyme 3 a (P-450 ALC ) is induced by alcohol administration and is effective in catalyzing the reaction: ethanol+0 2 +NADPH+H + → acetaldehyde +2H 2 O+NADP + . As judged by immuno-chemical quantitation, P-450 ALC is also induced in the animals by other diverse agents, including imidazole, trichlorethylene, acetone, pyrazole, and isoniazid. Evidence has been obtained for the occurrence of a protein immuno-chemically related to P-450 ALC in human liver microsomes and of a similar alcohol-inducible protein in the rat and in the normal and alcohol dehydrogenase-deficient deer-mouse. P-450 ALC catalyzes the activation of foreign compounds such as acetaminophen, various nitrosamines, and carbon tetrachloride and is therefore believed to play an important role in the enhanced toxicity of these substances accompanying alcohol administrationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46156/1/204_2004_Article_BF00296940.pd

Role of alcohol P-450-oxygenase (APO) in microsomal ethanol oxidation

The form of liver microsomal cytochrome P-450 induced by chronic administration of ethanol to rabbits, designated as P-450 or P-450 isozyme 3a, has been purified to homogeneity as judged by several criteria, including NH2- and COOH-terminal amino acid sequence determination. The reconstituted alcohol-P-450 oxygenase (APO) system containing P-450 and NADPH-cytochrome P-450 reductase catalyzes the oxidation of a variety of primary and secondary alcohols to aldehydes and ketones, including methanol, ethanol, n-propanol, n-butanol, 2-butanol, n-pentanol, and cyclohexanol. Other purified P-450 cytochromes, including isozymes 2, 3b, 3c, 4, and 6, are much less active than P-450 in the oxidation of alcohols. That P-450 functions in ethanol oxidation in liver microsomal membranes as well as in the reconstituted system was shown by immunochemical experiments involving inhibition by sheep anti-P-450 antibodies. We conclude that P-450 is the predominant ethanol-oxidizing cytochrome present after induction by chronic alcohol administration and that the other P-450 cytochromes have low but significant activity in both control and ethanol-induced animals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25797/1/0000359.pd

Comparison of six rabbit liver cytochrome P-450 isozymes in formation of a reactive metabolite of acetaminophen

This laboratory has recently reported the isolation of an ethanol-inducible form of rabbit liver microsomal cytochrome P-450, designated isozyme 3a. In view of the reports of others that the hepatotoxicity of acetaminophen is increased in ethanol-treated animals and the human alcoholic, we have determined the activity of the six available P-450 isozymes in the activation of the drug to give an intermediate which forms a conjugate with reduced glutathione. Isozymes 3a, 4, and 6, all of which are present in significant amounts in the liver microsomes from rabbits chronically admini-stered ethanol, exhibited the highest activities in the reconstituted enzyme system, whereas isozymes 3b and 3c were 10- to 20-fold less effective, and phenobarbital-inducible isozyme 2 was essentially inactive, even in the presence of cytochrome 5. The results obtained thus indicate that induction by ethanol of P-450 isozyme 3a (or a homologous enzyme in other species) may contribute to the toxicity of acetaminophen but that other cytochromes also play a significant role.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25240/1/0000682.pd

Alcohol metabolism and toxicity: Role of cytochrome P-450

A new isozyme of cytochrome P-450, designated form 3a on the basis of its relative electrophoretic mobility, has been purified to homogeneity from liver microsomes of rabbits treated chronically with ethanol. This cytochrome has the highest activity of the known rabbit P-450 isozymes in the oxidation of ethanol to acetaldehyde. In view of the reports of others that the hepatotoxicity of acetaminophen is increased in ethanol-treated animals and the human alcoholic, we have determined the activity of the six available P-450 isozymes in the activation of the drug to give an intermediate which forms a conjugate with reduced glutathione. Isozymes 3a, 4, and 6, the three major forms of cytochrome P-450 present in liver microsomes from rabbits chronically treated with ethanol, exhibited the highest activities in the recostituted enzyme system, whereas isozymes 3b and 3c were 10- to 20-fold less effective and phenobarbital-inducible isozyme 2 was essentially inactive, even in the presence of cytochrome b5. The results obtained thus indicate that induction by ethanol of P-450 isozyme 3a may contribute to the toxicity of acetaminophen but that other cytochromes also play a significant role.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24851/1/0000278.pd

Identification of P-450ALC in microsomes from alcohol dehydrogenase-deficient deermice: Contribution to ethanol elimination in vivo

Isozyme 3a of rabbit hepatic cytochrome P-450, also termed P-450ALC, was previously isolated and characterized and was shown to be induced 3- to 5-fold by exposure to ethanol. In the present study, antibody against rabbit P-450ALC was used to identify a homologous protein in alcohol dehydrogenase-negative (ADH-) and -positive (ADH+) deermice, Peromyscus maniculatus. The antibody reacts with a single protein having an apparent molecular weight of 52,000 on immunoblots of hepatic microsomes from untreated and ethanol-treated deermice from both strains. The level of the homologous protein was about 2-fold greater in microsomes from naive ADH- than from naive ADH+ animals. Ethanol treatment induced the protein about 3-fold in the ADH+ strain and about 4-fold in the ADH- strain. The antibody to rabbit P-450ALC inhibited the microsomal metabolism of ethanol and aniline. The homologous protein, termed deermouse P-450ALC, catalyzed from 70 to 80% of the oxidation of ethanol and about 90% of the hydroxylation of aniline by microsomes from both strains after ethanol treatment. The antibody-inhibited portion of the microsomal activities, which are attributable to the P-450ALC homolog, increased about 3-fold upon ethanol treatment in the ADH+ strain and about 4-fold in the ADH- strain, in excellent agreement with the results from immunoblots. The total microsomal P-450 content and the rate of ethanol oxidation were induced 1.4-fold and 2.2-fold, respectively, by ethanol in the ADH+ strain and 1.9-fold and 3.3-fold, respectively, in the ADH- strain. Thus, the total microsomal P-450 content and ethanol oxidation underestimate the induction of the P-450ALC homolog in both strains. A comparison of the rates of microsomal ethanol oxidation in vitro with rates of ethanol elimination in vivo indicates that deermouse P-450ALC could account optimally for 3 and 8% of total ethanol elimination in naive ADH+ and ADH- strains, respectively. After chronic ethanol treatment, P-450ALC could account maximally for 8% of the total ethanol elimination in the ADH+ strain and 22% in the ADH- strain. Further, cytochrome P-450ALC appears to be responsible for about one-half of the increase in the rate of ethanol elimination in vivo after chronic treatment with ethanol. These results indicate that the contribution of P-450ALC to ethanol oxidation in the deermouse is relatively small. Desferrioxamine had no effect on rates of ethanol uptake by perfused livers from ADH-negative deermice, indicating that ethanol oxidation by a hydroxyl radical-mediated mechanism was not involved in ethanol metabolism in this mutant. Peroxisomal [beta]-oxidation capacity was increased 40% over control values by ethanol treatment, consistent with the hypothesis that the increase in ethanol elimination in the ADH-negative deermouse is mediated predominantly via catalase-H2O2.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27237/1/0000244.pd

Ethanol Oxidation and Toxicity: Role of Alcohol P-450 Oxygenase

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66172/1/j.1530-0277.1986.tb05179.x.pd

Phase locking the spin precession in a storage ring

This letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/$c$ bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate ($\approx 121$ kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a one standard deviation range of $\sigma = 0.21$ rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles

The Effect of Oregon Pinot Noir on Endogenous Lipid Peroxidation

Degenerative diseases of aging such as cancer, cardiovascular disease, and brain dysfunction are increasingly found to have, in part, an oxidative origin. As a result, dietary antioxidants such as Vitamins C and E and carotenoids play a major role in minimizing this damage and preventing or delaying the pathophysiology. Population groups that generally do not smoke (a significant oxidative insult to the body), do not drink heavily, or do not eat much meat but instead have a diet rich in fruits and vegetables have an overall cancer mortality about half that of the general population and live several years longer. The failure to eat adequate levels of fruits and vegetables may result in significantly greater lipid peroxidation and oxidative damage of DNA and protein (1,2). There are numerous studies which suggest that moderate consumption of alcoholic beverages confers a beneficial effect on one's well being (3,4). This is due, in part, to the presence of phenolic compounds (such as flavonoids) that possess antioxidant properties in some alcoholic beverages. This is particularly true for red wines where the level of many flavonoids exceeds that found in white wines, beers, and distilled beverages. The long term goal of our studies is to determine what role phenolics found in Oregon Pinot noir have in the beneficial effects of red wine consumption that were reported in epidemiological studies. We initially determined the level of circulating 8-isoprostanes (5) in untreated rat plasma as an indicator of whole body oxidative stress. We found that the levels of circulating isoprostane in untreated rats were about 110 pg/ml using a commercially available ELISA. As a result, this assay will be valuable to assess lipid peroxidation after different long term treatments

The Effect of Phenolics Found in Oregon Pinot Noir on Macrophage Gene Expression 1997-1998

Degenerative diseases of aging such as cancer, cardiovascular disease, and brain dysfunction are increasingly found to have, in part, an oxidative origin. As a result, dietary antioxidants play a major role in minimizing this damage and preventing or delaying the pathophysiology. Population groups that generally do not smoke (a significant oxidative insult to the body), do not drink heavily, or do not eat much meat, but instead have a diet rich in fruits and vegetables have an overall cancer mortality about half that of the general population and live several years longer