Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plasma ACTH and cortisol levels do not change during aging. On the other hand, the plasma dehydroepiandrosterone sulfate (DHEA-S) changes remarkably during aging. Before puberty, the plasma DHEA-S level both in males and females is very low, however, it rapidly increases at puberty, and thereafter significantly decreases both linearly and age-dependently. Cytochrome P450c17 has two enzyme activities, 17-alpha-hydroxylase and 17,20-lyase. Cortisol is synthesized by 17-alpha-hydroxylase, and DHEA is synthesized by 17,20-lyase. The mechanism of dissociation of cortisol and DHEA synthesis in aging depends on another regulator of 17,20-lyase of cytochrome P450c17 such as cytochrome P450 reductase. We demonstrated significant decrease in cytochrome P450 reductase activity in bovine aged adrenal glands. We clarified the beneficial effects of DHEA as an anti-aging steroid based on both in vitro and in vivo experiments, such as the stimulatory effect of immune system, anti-diabetes mellitus, anti-atherosclerosis, anti-dementia (neurosteroid), anti-obesity and anti-osteoporosis. It is very important to identify the mechanism of action of DHEA. We clarified the conversion of DHEA to estrone by cytochrome P450 aromatase in primary cultured human osteoblasts. We indentified high affinity of DHEA binding with K(d)=6.6 nM in antigen and DHEA stimulated human T lymphocytes. We searched for the target genes that are specifically induced in activated T lymphocytes in the presence of DHEA by subtractive hybridization screening for differentially expressed transcripts. The double blind, randomized human replacement therapies utilizing DHEA are also reviewed.
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PMID:Mechanism of action of anti-aging DHEA-S and the replacement of DHEA-S. 1204 59

Variations of estrogen (produced mostly in the ovaries) are under enzymatic influence of aromatases, acting also as oncogenes through the cytochrome CYP17 and CYP19. Their degradation trough methoxylation, resulting in both carcinogenetic and protector compounds, is influenced by 2, 4 and 16 +/- hydrolases. Tissue sensibility to oestrogen depends on the amount of receptors and the plasma level of oestrogen. They are regulating cell's growth and differentiation, depending on subject's age. Paraclinic markers such as the amount of regulating receptors, plasma oestrogen level, breast density and bone density are elements in evaluating breast cancer risk. Among the risk factors of occurrence and development of breast cancer were cited also early menarche, late term pregnancy, late menopause, postmenopausal obesity, smoking and the diet rich in fats and fatty acids, alcohol and antioxidant vitamins.
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PMID:[Breast cancer-estrogens relationship]. 1273 Nov 98

The pathology of the liver in alcoholic steatosis and alcoholic steatohepatitis (ASH) is remarkably similar to that of nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), suggesting some common pathogenic mechanism. Studies carried out over the last three decades of possible mechanisms involved revealed one common link, namely the induction of cytochrome P4502E1. Its substrates include fatty acids, ketones and ethanol. These substances, when present chronically in large amounts, induce the activity of the enzyme which thereby contributes to the disposition of these substrates. This reaction, however, is associated with the release of free radicals which can cause lipid peroxidation and liver injury, including mitochondrial damage. Mitochondrial damage in turn exacerbates the oxidative stress. CYP2E1 can also convert various xenobiotics to toxic metabolites. When unchecked, this toxicity eventually results in inflammation and fibrosis, culminating in cirrhosis. Prevention of this disorder is based on limiting the substrates that induce the system, such as excessive fatty acid associated with obesity and excessive alcohol consumption. No effective pharmacologic treatment is presently available but there is ongoing research on possible inhibitors of CYP2E1, innocuous enough to be suitable for chronic human consumption and sufficiently effective to attenuate the CYP2E1 induction to avoid the consequences of its excessive activity while maintaining its physiologic role.
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PMID:CYP2E1: from ASH to NASH. 1473 44

BACKGROUND:: Nonalcoholic steatohepatitis is most often attributed to the effects of obesity, hyperlipidemia, diabetes mellitus and drugs. It is still unknown whether livers with steatohepatitis are more vulnerable to toxic damage. AIM:: To determine the effect of the hepatotoxicant thioacetamide in a rat nutritional model of hepatic steatohepatitis. METHODS:: Steatohepatitis was induced in rats by placing them on a methionine-choline deficient diet for 1 month. Thioacetamide was administered by three consecutive intraperitoneal injections (300mg/kg) at 24h intervals. RESULTS:: Following treatment with thioacetamide, the elevated serum levels of liver enzymes and blood ammonia, liver necroinflammation and the survival rate after 48h were not different between rats with normal or fatty liver. However, those parameters were significantly worse when steatohepatitis regressed after return to normal diet for 1 month (P < 0.01). Western blot analysis of hepatic extracts revealed no difference in cytochrome P4502E1 levels between livers with steatohepatitis and steatohepatitis after regression, suggesting that the enhanced hepatotoxicity after regression of steatohepatitis could not be attributed to increased cytochrome P4502E1. CONCLUSIONS:: In a nutritional model of steatohepatitis, rats with fatty liver were not more vulnerable than normal rats to liver damage induced by thioacetamide. However, liver damage was significantly more severe in rats with steatohepatitis after 1 month regression.
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PMID:Thioacetamide-induced hepatic damage in a rat nutritional model of steatohepatitis. 1558 79

Acrylamide, an animal carcinogen and germ cell mutagen present at low (ppm) levels in heated carbohydrate-containing foodstuffs, is oxidized by cytochrome P4502E1 (CYP2E1) to the epoxide glycidamide, which is believed to be responsible for the mutagenic and carcinogenic activity of acrylamide. We recently reported a comparison of the effects of acrylamide on the genetic integrity of germ cells of male wild-type and CYP2E1-null mice [B.I. Ghanayem, K.L. Witt, L. El-Hadri, U. Hoffler, G.E. Kissling, M.D. Shelby, J.B. Bishop, Comparison of germ-cell mutagenicity in male CYP2E1-null and wild-type mice treated with acrylamide: evidence supporting a glycidamide-mediated effect, Biol. Reprod. 72 (2005) 157-163]. In those experiments, dose-related increases in dominant lethal mutations were detected in uterine contents of female mice mated to acrylamide-treated wild-type males but not CYP2E1-null males, clearly implicating CYP2E1-mediated formation of glycidamide in the induction of genetic damage in male germ cells. We hypothesized that acrylamide-induced somatic cell damage is also caused by glycidamide. Therefore, to examine this hypothesis, female wild-type and CYP2E1-null mice were administered acrylamide (0, 25, 50mg/kg) by intraperitoneal injection once daily for 5 consecutive days. Twenty-four hours after the final treatment, blood and tissue samples were collected. Erythrocyte micronucleus frequencies were determined using flow cytometry and DNA damage was assessed in leukocytes, liver, and lung using the alkaline (pH>13) single cell gel electrophoresis (Comet) assay. Results were consistent with the earlier observations in male germ cells: significant dose-related increases in micronucleated erythrocytes and DNA damage in somatic cells were induced in acrylamide-treated wild-type but not in the CYP2E1-null mice. These results support the hypothesis that genetic damage in somatic and germ cells of mice-treated with acrylamide is dependent upon metabolism of the parent compound by CYP2E1. This dependency on metabolism has implications for the assessment of human risks resulting from occupational or dietary exposure to acrylamide. CYP2E1 polymorphisms and variability in CYP2E1 activity associated with, for example, diabetes, obesity, starvation, and alcohol consumption, may result in altered metabolic efficiencies leading to differential susceptibilities to acrylamide toxicities in humans.
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PMID:Absence of acrylamide-induced genotoxicity in CYP2E1-null mice: evidence consistent with a glycidamide-mediated effect. 1598 77

Obesity and type 2 diabetes have been associated with a high-fat diet (HFD) and reduced mitochondrial mass and function. We hypothesized a HFD may affect expression of genes involved in mitochondrial function and biogenesis. To test this hypothesis, we fed 10 insulin-sensitive males an isoenergetic HFD for 3 days with muscle biopsies before and after intervention. Oligonucleotide microarray analysis revealed 297 genes were differentially regulated by the HFD (Bonferonni adjusted P < 0.001). Six genes involved in oxidative phosphorylation (OXPHOS) decreased. Four were members of mitochondrial complex I: NDUFB3, NDUFB5, NDUFS1, and NDUFV1; one was SDHB in complex II and a mitochondrial carrier protein SLC25A12. Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC1) alpha and PGC1beta mRNA were decreased by -20%, P < 0.01, and -25%, P < 0.01, respectively. In a separate experiment, we fed C57Bl/6J mice a HFD for 3 weeks and found that the same OXPHOS and PGC1 mRNAs were downregulated by approximately 90%, cytochrome C and PGC1alpha protein by approximately 40%. Combined, these results suggest a mechanism whereby HFD downregulates genes necessary for OXPHOS and mitochondrial biogenesis. These changes mimic those observed in diabetes and insulin resistance and, if sustained, may result in mitochondrial dysfunction in the prediabetic/insulin-resistant state.
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PMID:A high-fat diet coordinately downregulates genes required for mitochondrial oxidative phosphorylation in skeletal muscle. 1598 91

The role of cytochrome P4502E1 in metabolism of substances, polymorphism, ways of the expression regulation, change of activity in pathological condition is considered in the review. Cytochrome P4502E1 catalyzed first two reactions of acetone transformation in the lactic acid, ethanol oxidation, metabolism of fatty acids and their hydroperoxides. Cytochrome P4502E1 dependent metabolism of xenobiotics in many cases results in formation of toxic intermediates and radicals of oxygen. Regulation of cytochrome P4502E1 expression includes transcriptional mechanisms and substrate stabilization of its molecule. The enzyme activity grows in alcoholism, diabetes mellitus, obesity, steatohepatitis, administration of acetone, alcohols and is connected with intensification of toxicity of paracetamol, halothane, benzene, tetrachlororomethane and others xenobiotics. Such inhibitors of cytochrome P4502E1 as dialyl sulphide, disulfiram have hepatoprotective action.
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PMID:[Cytochrome P4502E1. Polymorphism, physiological function, regulation, and role in pathology]. 1610 Aug 94

Polycystic ovary syndrome (PCOS) is a common heterogenous endocrine disorder associated with amenorrhoea (or oligomenorrhoea), hyperandrogenism, hirsutism, obesity, insulin resistance, and an approximately 7-fold increased risk of type 2 diabetes mellitus (NIDDM - non-insulin dependent diabetes mellitus). It is a leading cause of female infertility. The prevalence of PCOS among reproductive-age women has been estimated at 4%-12%. Familial aggregation of this syndrome is well established. There are also ethnic and racial variations in the prevalence of the syndrome and its symptoms. Multiple biochemical pathways have been implicated in the pathogenesis of PCOS. Several genes from these pathways have been tested include genes involved in steroid hormone biosynthesis and metabolism (StAR, CYP11, CYP17, CYP19 HSD17B1-3, HSD3B1-2), gonadotropin and gonadal hormones action (ACTR1, ACTR2A-B, FS, INHA, INHBA-B, INHC, SHBG, LHCGR, FSHR, MADH4, AR), obesity and energy regulation (MC4R, OB, OBR, POMC, UCP2-3), insulin secretion and action (IGF1, IGF1R, IGFBPI1-3, INS VNTR, IR, INSL, IRS1-2, PPARG) and many others. Most women with PCOS, both obese and lean, have a degree of insulin resistance. The minisatellite of insulin gene (INS VNTR), especially class III alleles and III/III genotypes might not only determine the predisposition to anovulatory PCOS but also the concomitant risk for development of type 2 diabetes. The function of the insulin receptor (IR) is probably normal in woman with PCOS. However abnormal serine phosphorylation in the receptor may impair signal transduction accounting for a post-binding defect in insulin action. Serine phosphorylation is also involved in the postranslational regulation of 17,20-lyase activity (CYP17). There may be a common aetiology for both insulin resistance and hyperandrogenism. Polymorphic alleles of both IRS-1 and IRS-2 (insulin receptor substrate 1 - 2), alone or in combination, may have a functional impact on the insulin-resistant component of PCOS. There is no evidence to suggest that follistatin gene polymorphisms play a role in the pathogenesis of insulin resistance in PCOS women. PCOS appears to be associated with the absence of the four-repeat-units allele in a polymorphic region of pentanucleotide (TTTTA)n repeats within CYP11A gene, which encodes cytochrome P450scc. It has been hypothesized that up-regulation of this enzyme could lead to increased androgen production. There is no evidence of any association of alleles of CYP19 gene (encoding cytochrome P450arom) with PCOS. Association exists between androgen receptor gene (AR) polymorphisms an androgens action in PCOS. Increased hirustism and decreased CAG repeat length within AR gene has been also demonstrated in women with normal testosterone levels. Expression of estrogen receptor (ERs) as well as 5-alpha-reeducates (SRD5A1-2 genes) activity was analysed in granulosa (GC) and theca cells (TC). The results of this study demonstrate that there are significant alterations in the expression of ERalpha and ERbeta in PCOS that may be related to abnormal follicular development. On the other hand elevated SRD5A activity in polycystic ovaries supported the hypothesis that 5-alpha-reduced androgens may play a role in the pathogenesis of the syndrome. The genetic aetiology of PCOS remains unknown. There are a number of interlinking factors that affects expression of PCOS. Single cause of PCOS is unlikely. Other possible mechanisms in pathogenesis of PCOS are discussed.
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PMID:[Genetic aspects of polycystic ovary syndrome]. 1635 Jul 21

The biochemical differences between simple steatosis, a benign liver disease, and non-alcoholic steatohepatitis, which leads to cirrhosis, are unclear. Fat aussie is an obese mouse strain with a truncating mutation (foz) in the Alms1 gene. Chow-fed female foz/foz mice develop obesity, diabetes, and simple steatosis. We fed foz/foz and wildtype mice a high-fat diet. Foz/foz mice developed serum ALT elevation and severe steatohepatitis with hepatocyte ballooning, inflammation, and fibrosis; wildtype mice showed simple steatosis. Biochemical pathways favoring hepatocellular lipid accumulation (fatty acid uptake; lipogenesis) and lipid disposal (fatty acid beta-oxidation; triglyceride egress) were both induced by high-fat feeding in wildtype but not foz/foz mice. The resulting extremely high hepatic triglyceride levels were associated with induction of mitochondrial uncoupling protein-2 and adipocyte-specific fatty acid binding protein-2, but not cytochrome P4502e1 or lipid peroxidation. In this model of metabolic syndrome, transition of steatosis to steatohepatitis was associated with hypoadiponectinemia, a mediator of hepatic fatty acid disposal pathways.
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PMID:Adaptive failure to high-fat diet characterizes steatohepatitis in Alms1 mutant mice. 1651 52

Adiponectin, the most abundantly synthesized protein in adipose tissue, has plieotropic effects on liver, muscle, endothelium, placenta, and other tissues. We examined direct effects of recombinant porcine adiponectin on porcine ovarian granulosa cells in vitro. We demonstrate that adiponectin, at physiologically relevant levels (10-25 microg/ml), provokes expression of genes associated with periovulatory remodeling of the ovarian follicle over a time frame of 6-24 h. These include cyclooxygenase-2, prostaglandin E synthase, and vascular endothelial growth factor. Adiponectin modulates steroid synthetic protein gene expression, increasing steroidogenic acute regulatory protein transcript abundance and reducing cytochrome P450aromatase. Adiponectin has antidiabetic properties and sensitizes tissues to insulin. We show that it interacts with both LH and insulin in inducing expression of cyclooxygenase-2 transcripts in granulosa cells. We determined that the MAPK pathway, via phosphorylation of ERK1/2, is involved in mediation of the adiponectin signal in ovarian granulosa cells, rather than protein kinase A or the classic adiponectin transducer, AMP-activated protein kinase. Adiponectin synthesis is reduced in obesity, and our findings suggest that this reduction plays a role in obesity-related ovarian dysfunction.
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PMID:Adiponectin induces periovulatory changes in ovarian follicular cells. 1691 53


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