Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A model has been developed for the administration to rats and baboons of ethanol as part of a nutritionally adequate liquid diet. With this regimen, ethanol intake was much higher than with conventional procedures. All animals gained or maintained their body weight, and liver morphology was normal in the controls. Isocaloric substitution of carbohydrate by ethanol (36% of total calories in rats and 50% in baboons) resulted in the production of fatty liver in all animals, while the baboons also developed alcoholic hepatitis and cirrhosis with increased activities of serum glutamic oxaloacetic transaminase. Inebriation and manifestation of dependence on withdrawal of the diet were observed in baboons and quantitated in the rat. Chemical alterations produced by ethanol at the fatty liver stage were characterized by hyperlipemia, striking triglyceride accumulation in the liver, and enhanced activities of microsomal drug metabolizing enzymes, including the microsomal ethanol oxidizing system (MEOS). In showing that all aspects of liver injury observed in alcoholics can be reproduced in animals by the feeding of pure ethanol with an adequate diet, this study incriminates ethanol itself as a cause for the hepatic complications. This new experimental model is proposed as a tool for the study of the pathogenesis and treatment of alcoholic liver injury and dependence.
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PMID:Animal models of ethanol dependence and liver injury in rats and baboons. 94 46

A model has been developed for the administration to rats and baboons of ethanol as part of a nutritionally adequate liquid diet. With this regimen, ethanol intake was much higher than with conventional procedures. All animals gained or maintained their body weight, and liver morphology was normal in the controls. Isocaloric substitution of carbohydrate by ethanol (36% of total calories in rats and 50% in baboons) resulted in the production of fatty liver in all animals, while the baboons also developed alcoholic hepatitis and cirrhosis with increased activities of serum glutamic oxaloacetic transaminase. Inebriation and manifestation of dependence upon withdrawal of the diet were observed in baboons and quantitated in the rat. Chemical alterations produced by ethanol at the fatty liver stage were characterized by hyperlipemia, striking triglyceride accumulation in the liver and enhanced activities of microsomal drug metabolizing enzymes, including the microsomal ethanol oxidizing system (MEOS). Ultrastructural changes of the mitochondria and the endoplasmic reticulum were already present at the fatty liver stage and persisted throughout the hepatitis and cirrhosis. The lesions were similar to those observed in alcoholics (including the inflammation and the central sclerosis), and differed strikingly from the alterations produced by other models of liver injury. In showing that all aspects of liver injury observed in alcoholics can be reproduced in animals by the feeding of pure ethanol with an adequate diet, this study incriminates ethanol itself as a cause for the hepatic complications. This new experimental model is proposed as a tool for the study of the pathogenesis and treatment of alcoholic liver injury and dependence.
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PMID:Alcoholic liver injury: experimental models in rats and baboons. 123 25

Non-alcoholic steatohepatitis resembles alcoholic liver disease in hepatic morphology but appears to have a different natural history. We sought to assess the nature of non-alcoholic steatohepatitis by a prospective study of its clinical progression and the relationship of biochemical abnormalities to changes in serum lipids among 15 patients with this disorder. In addition, antipyrine clearance (Cl-AP), which reflects hepatic microsomal oxidative capacity, was measured serially. Although initial liver histology included micronodular cirrhosis in five cases and bridging fibrosis in another three, only one patient developed a hepatic complication during 1-10 years (median: 3.7) of follow up. This confirms the relatively benign nature of non-alcoholic steatohepatitis. Moreover, Cl-AP, which was below the normal range in 13 patients, did not change significantly during 10-40 months of follow up. However, compared with other chronic liver diseases, the reduced Cl-AP was disproportionately low relative to the uniformly normal serum albumin concentration and other indices of hepatic metabolic function. This is consistent with selective impairment of endoplasmic reticular drug oxidizing enzymes. Hyperlipidaemia was present in 11 patients. In three of these, diet-induced correction of serum triglyceride elevation was associated with reduction of hepatocellular damage as indicated by serum enzyme levels. A hypothesis that unites these and earlier findings is that release of cytokines may occur in non-alcoholic steatohepatitis and produce accumulation of free fatty acids in the liver, leading to focal necro-inflammatory lesions and the destruction or down-regulation of cytochrome P450.
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PMID:Non-alcoholic steatohepatitis: impaired antipyrine metabolism and hypertriglyceridaemia may be clues to its pathogenesis. 178 74

Hypothyroidism is a cause of secondary hyperlipidaemia. This study investigates the frequency of biochemically diagnosed hypothyroidism and its relationship with plasma cholesterol concentration in apparently healthy people. Thyroid function tests (total T4, TSH, and free T4) were performed on 272 apparently healthy men and women (179 vegetarians, 93 meat eaters) with a plasma cholesterol concentration above 7 mmol/l and on 90 individuals with a plasma cholesterol below 4.1 mmol/l who were matched for age, sex and dietary habits. Six per cent of those with a plasma cholesterol above 7 mmol/l had biochemical evidence of hypothyroidism as defined by a TSH greater than 10 mIU/l (reference range 1-6) and a low free T4 below 10 pmol/l (reference range 10.1-25). Eighty per cent of these people had a high titre of thyroid anti-microsomal antibodies. Of the 90 individuals with a plasma cholesterol level below 4.1 and the 25 randomly selected participants none had biochemical evidence of hypothyroidism. Hypothyroidism is relatively common in apparently healthy people with a raised plasma cholesterol. It appears no commoner in vegetarians than in meat eaters.
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PMID:Asymptomatic hypothyroidism and hypercholesterolaemia. 143 76

The effects of oral contraceptives (OCs) on drug therapy are related mainly to the inhibition of microsomal oxidation as well as the induction of enzymes involved in conjugation reactions. Since many drugs share these catabolic pathways, their pharmacodynamics will be affected by OCs. Notable interactions include an increased bioavailability of analgesics, tranquilizers, and tricyclic antidepressants. OCs increase the risk for hypertension, and pharmacokinetic interactions are to be expected when OCs are administered with antihypertensive drugs. Likewise, OCs affect lipid metabolism and thus modify the effects of atherogenic drugs; however, the different forms of hyperlipidemia show a heterogeneous response to OCs. Another particular concern is that the gestagen components of OCs may cause peripheral insulin resistance and may require dose adaption with antidiabetic treatments. Two common nonprescription drugs, theophylline and caffeine, show decreased clearance rates due to OCs. All share a common oxidation pathway involving cytochrome P-450 and P-448. However, cigarette smoking stimulates these enzymes, and the decreased clearance of theophylline and caffeine is usually not observed in smokers. The reports of effects of OCs and alcohol taken together are mixed, and no clinically relevant conclusions can be drawn. Most vitamin and mineral levels are influenced by OCs, but this is a concern only under conditions of deprived diet, when normal dietary adjustments are impossible. An important caveat of the many documented effects of OCs on the pharmacodynamics of other drugs is that, in most instances, these effects will be counterbalanced with kinetic changes and result in no clinical manifestation. Nevertheless, clinicians must be aware of possible adverse reactions, particularly in predisposed patients.
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PMID:Influence of oral contraceptives on drug therapy. 225 28

Steroid metabolism in Nagase Analbuminemia Rats (NAR), a mutant strain established from Sprague-Dawley rats, was studied. NAR are characterized by lack of serum albumin and hyperlipidemia. Total testosterone concentration in the serum of NAR was lower than that of normal rats, while the serum free testosterone, LH and FSH concentrations were similar. The half lives of 14C-labeled testosterone administered intravenously in NAR and normal Sprague-Dawley (SD) rats were 4.4 and 4.1 min, respectively. The plasma clearance rates of testosterone in NAR and normal rats were 34.7 and 39.1 ml/min per kg body weight. On Sephadex G-100 chromatography, a mixture of [3H]testosterone and normal rat serum gave two protein peaks eluted in the void volume and the albumin fraction, and the radioactivity was eluted all in the albumin fraction. In contrast, a mixture of [3H]testosterone and NAR serum gave a single protein peak eluted in the void volume and the radioactivity was mainly eluted with this protein peak. The association constants of testosterone to NAR and normal rat sera were 1.25 and 2.24 X 10(4) M-1. Enzyme activities related to the synthesis of testosterone by the testicular microsomal fractions of NAR and normal rats were examined. The activities of 3 beta-hydroxysteroid dehydrogenase, 5-ene-4-ene isomerase, 17 alpha-hydroxylase, C-17-C-20 lyase and 17 beta-hydroxysteroid dehydrogenase were lower in NAR than in normal rats. The activity for synthesis of testosterone from pregnenolone by the testicular microsomal fraction of NAR was about 40% of that of normal rats. These findings indicate that the low serum concentration of testosterone in NAR is mainly attributable to decreased biosynthesis of testosterone in the testes.
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PMID:Reduced activity of androgen biosynthesis in the testes of rats with analbuminemia. 308 76

Advances in our knowledge of the microsomal metabolism of ethanol enable us to understand a number of complications that develop in the alcoholic. After chronic ethanol consumption, microsomal ethanol-oxidizing system (MEOS) activity increases with an associated rise in microsomal cytochrome P-450, including a form different from that induced by phenobarbital and methylcholanthrene and which has a high affinity for ethanol, as shown in reconstituted systems. The role of this MEOS in vivo and its increase after chronic ethanol consumption was most conclusively shown in alcohol dehydrogenase-negative deer mice. Microsomal induction is also associated with enhanced metabolism of other drugs, resulting in metabolic drug tolerance. Furthermore, there is increased conversion to toxic metabolites of known hepatotoxic agents (such as CCl4), which may explain the enhanced susceptibility of alcoholics to the toxicity of industrial solvents. Furthermore, the ethanol-induced form of cytochrome P-450 has a high capacity for the conversion to toxic metabolites of some commonly used drugs, such as acetaminophen, and also carcinogens, such as dimethylnitrosamine which is activated at concentrations much lower than those required for other microsomal inducers. Moreover, catabolism of retinol is accelerated through a newly discovered microsomal pathway, thereby contributing to hepatic vitamin A depletion and possibly vitamin A toxicity. There is also induction of microsomal enzymes involved in lipoprotein production, resulting in hyperlipemia. Contrasting with the chronic effects of ethanol consumption, acutely, ethanol inhibits the metabolism of other drugs through competition for an at least partially shared microsomal detoxification pathway.
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PMID:Microsomal ethanol-oxidizing system. 310 31

The hypolipidemic activity of tiadenol-disulfoxide, the major metabolite of 1,10-bis(hydroxyethylthio)decane (tiadenol, Eulip) in man and in the rat was assessed in various experimental models versus the corresponding activity of tiadenol. Tiadenol-disulfoxide in the normolipidemic rats lowers total serum cholesterol and serum and liver triglycerides in an extent comparable to that of the reference compound. Likewise, it is equally effective as tiadenol in preventing Triton-induced hyperlipidemia and Nath diet induced hypercholesterolemia; in addition tiadenol-disulfoxide is slightly more effective than tiadenol in increasing HDL-cholesterol in hypercholesterolemic rats. At hypolipidemic doses the compound causes no hepatomegaly, no induction of peroxisomal catalase and palmitoyl-CoA oxidase activities, no smooth endoplasmic reticulum proliferation and no induction of microsomal cytochrome P-450 and of cytochrome P-450 dependent enzyme activities: aminopyrine (aminophenazone) N-demethylase, aniline hydroxylase, zoxazolamine hydroxylase and hexobarbital oxidase. At the suprapharmacological dose of 300 mg/kg tiadenol-disulfoxide, if compared to the reference compound, shows a generally lower order of toxicity on these hepatic parameters. Orally administered tiadenol-disulfoxide is well absorbed by the gastrointestinal tract and is eliminated in urine at 45% of the dose in unchanged form, and the remaining being: glucuron-conjugated tiadenol-disulfoxide (10%), S-oxidized metabolites (15%) and sulfoxidized carboxylic metabolites (15%). The compound is well tolerated both in mice and rats. The results of this comparative study demonstrate that: 1. tiadenol-disulfoxide is a substance with promising hypolipidemic properties; 2. tiadenol-disulfoxide is largely responsible for the hypolipidemic activity of tiadenol; 3. hepatomegaly consequent to tiadenol administration is the consequence of the response of the liver cell to the increased functional demand of the mixed function oxidase (MFO) system involved in the metabolism of the drug; 4. peroxisomal enzyme activities induction observed with both drugs at non-pharmacological doses does not play any role in their hypolipidemic action and is not associated with hepatomegaly.
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PMID:Experimental studies on pharmacology, metabolism and toxicology with tiadenol-disulfoxide. Dissociation of lipid lowering effects and the induction of peroxisomal and microsomal drug-metabolizing enzymes. 366 66

Effect of chronic ethanol administration on some enzyme activities was studied in plasma membranes, brain homogenate cytoplasmic reticulum and cytosol, liver homogenate and microsomal fractions and blood serum. Ethanol was ingested as a constituent of isocaloric "semiliquid" diet. The investigation was carried out to estimate the diagnostic value of certain enzymes in evaluation of alcohol intoxication. In male rats ethanol caused remarkable hyperlipidemia, accumulation of lipids in liver tissue and elevation of gamma-glutamyl transpeptidase activity in blood serum and brain tissue. In liver tissue moderate induction of glucose-6-phosphatase, NADPH-cytochrome c reductase and alkaline phosphatase was observed. The putative mechanism of elevation of organospecific enzyme activities in blood serum during chronic ethanol consumption is discussed.
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PMID:[Effect of chronic administration of ethanol on the enzyme activity of rat serum, liver and brain]. 614 65

Ther are several main mechanisms that allow us to understand a number of the hepatic and metabolic effects of ethanol. Ethanol is oxidized in the liver to two products (hydrogen and acetaldehyde), to which many of the effects of ethanol can be attributed. The hydrogen generated alters the redox state, and though this effect is attenuated after chronic ethanol consumption, it may still be sufficient to explain alterations in lipid metabolism, possibly increased collagen deposition, and, under special circumstances, depression of protein synthesis. Acetaldehyde impairs microtubules, decreases protein secretion, and causes protein retention and ballooning of the hepatocyte. Acetaldehyde exerts toxicity also with regard to other key cellular functions, particularly in the mitochondria, and it may promote peroxidation of the cellular membranes. It is noteworthy that after chronic consumption of ethanol, there is increased acetaldehyde, in part because of decreased disposition in the mitochondria and partly because of induction of an alternative pathway of ethanol metabolism, namely the microsomal ethanol-oxidizing system. Indeed, this MEOS increases in activity after chronic ethanol consumption, with cross induction and acceleration of the metabolism of other drugs and increased lipoprotein production with hyperlipemia. There is also increased microsomal activation of hepatotoxic compounds (including drugs and possibly vitamin A). Fibrosis and cirrhosis can develop despite an associated adequate diet and even in the absence of alcoholic hepatitis. They are preceded by myofibroblasts and fibroblast proliferation. What eventually causes the increased number of myofibroblasts and promotes fibrosis is unclear, nor do we know the relative role of hepatocytes or mesenchymal cells in the process of fibroplasis. Possibly selective roles in this process of specific nutritional factors remain to be elucidated.
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PMID:Alcohol, protein nutrition, and liver injury. 634 74


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