Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027497 (nausea)
 23,468 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lovastatin, an inhibitor of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (the major regulatory enzyme of the mevalonate pathway of cholesterol synthesis), displays antitumor activity in experimental models. We therefore conducted a Phase I trial to characterize the tolerability of lovastatin administered at progressively higher doses to cancer patients. From January 1992 to July 1994, 88 patients with solid tumors (median age, 57 +/- 14 years) were treated p.o. with 7-day courses of lovastatin given monthly at doses ranging from 2 to 45 mg/kg/day. The inhibitory effects of lovastatin were monitored through serum concentrations of cholesterol and ubiquinone, two end products of the mevalonate pathway. Concentrations of lovastatin and its active metabolites were also determined, by bioassay, in the serum of selected patients. Cyclical treatment with lovastatin markedly inhibited the mevalonate pathway, evidenced by reductions in both cholesterol and ubiquinone concentrations, by up to 43 and 49% of pretreatment values, respectively. The effect was transient, however, and its magnitude appeared to be dose independent. Drug concentrations reached up to 3.9 micrometer and were in the range associated with antiproliferative activity in vitro. Myopathy was the dose-limiting toxicity. Other toxicities included nausea, diarrhea, and fatigue. Treatment with ubiquinone was associated with reversal of lovastatin-induced myopathy, and its prophylactic administration prevented the development of this toxicity in a cohort of 56 patients. One minor response was documented in a patient with recurrent high-grade glioma. Lovastatin given p.o. at a dose of 25 mg/kg daily for 7 consecutive days is well tolerated. The occurrence of myopathy, the dose-limiting toxicity, can be prevented by ubiquinone supplementation. To improve on the transient inhibitory activity of this dosing regimen on the mevalonate pathway, alternative schedules based on uninterrupted administration of lovastatin should also be studied.
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PMID:Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer. 981 94

A thirty-two-year-old woman who had been diagnosed MELAS with 3243A > G mutation presented headache, nausea, decreased bilateral visual acuity, and topographical disturbance on January 1 in 2002. Although brain CT showed no fresh lesion, recurrence of stroke-like episode was considered. Immediately, she was treated with ubiquinone (210 mg/day, p.o.) and tocopherol nicotinate (300 mg/day, p.o.). She became confused on the fifth day. Diffusion weighted- and T2 weighted-MRI revealed appearance of hyperintense lesion at the right occipital lobe. We started edaravone infusion (30 mg, twice a day, div.) for two weeks with informed consent from her family. On 13th day her consciousness was improved. Edema and signal intensity of the lesion were decreased on MRI with minimal spread to the parietal lobe. She discharged on the 30th day with marked visual field loss, hemispatial neglect, and topographical amnesia. MRI after four months showed remarkable atrophy of the right occipital region. In our department, five stroke-like episodes including this case were treated with ubuiquinone and tocopherol nicotinate. This regimen was effective in prevention of progressive spread of lesions only in two episodes. Edaravone is radical scavenger used in acute cerebral infarction. Progressive spread into the neighboring regions is one of characteristics of MELAS, although its precise mechanisms are not well known. Oxidative stress induced by released free radicals through mitochondrial dysfunction might be one of factors and edaravone would make an effect through blockage of the free radicals. Edaravone could not rescue neurons in the initial lesion. Although more numbers of cases are needed to establish the effect of edaravone on MELAS, it could minimize the neurological deficits after stroke-like episode of MELAS.
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PMID:[A case of stroke-like episode of MELAS of which progressive spread would be prevented by edaravone]. 1602 65

Papyriferic acid (PA) is a triterpene that is secreted by glands on twigs of the juvenile ontogenetic phase of resin producing tree birches (e.g., Betula neoalaskana, B. pendula) and that deters browsing by mammals such as the snowshoe hare (Lepus americanus). We investigated the pharmacology of PA as a first step in understanding its antifeedant effect. After oral administration to rats, PA and several metabolites were found in feces but not urine, indicating that little was absorbed systemically. Metabolism involved various combinations of hydrolysis of its acetyl and malonyl ester groups, and hydroxylation of the terpene moiety. The presence of a malonyl group suggested a possible interaction with succinate dehydrogenase (SDH), a mitochondrial enzyme known to be competitively inhibited by malonic acid. The effect of PA on the oxidation of succinate by SDH was examined in mitochondrial preparations from livers of ox, rabbit, and rat. In all three species, PA was a potent inhibitor of SDH. Kinetic analysis indicated that, unlike malonate, PA acted by an uncompetitive mechanism, meaning that it binds to the enzyme-substrate complex. The hydrolysis product of PA, betulafolienetriol oxide, was inactive on SDH. Overall, the evidence suggests that PA acts as the intact molecule and interacts at a site other than the succinate binding site, possibly binding to the ubiquinone sites on complex II. Papyriferic acid was potent (K(iEIS) ranged from 25 to 45 microM in the three species) and selective, as malate dehydrogenase was unaffected. Although rigorous proof will require further experiments, we have a plausible mechanism for the antifeedant effect of PA: inhibition of SDH in gastrointestinal cells decreases mitochondrial energy production resulting in a noxious stimulus, 5-HT release, and sensations of nausea and discomfort. There is evidence that the co-evolution of birches and hares over a large and geographically-diverse area in Northern Europe and America has produced marked differences in the formation of PA by birches, and the tolerance of hares to dietary PA. The present findings on the metabolic fate and biochemical effects of PA provide a rational basis for investigating the mechanisms underlying differences among populations of hares in their tolerance of a PA-rich diet.
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PMID:Papyriferic acid, an antifeedant triterpene from birch trees, inhibits succinate dehydrogenase from liver mitochondria. 1983 55