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)

Phenotypically distinct but genetically identical obese mottled yellow Avy/a and lean pseudoagouti Avy/a sibling mice and their congeneic black a/a littermates provide an experimental system for distinguishing phenotypic effects from genotypic effects in the expression of the genotype at the organismic level. Hepatic glutathione S-transferase activity in obese yellow Avy/a (YS X VY) F-1 hybrid female mice was only about 66% of that found in their lean black a/a sisters. This decreased enzyme activity was not a direct effect of the Avy/a genotype but was associated with the obesity of the yellow mice since the enzyme activity in lean pseudoagouti Avy/a female siblings was similar to that found in the black a/a mice. Long-term feeding of 160 ppm lindane in the diet decreased the enzyme activity in all phenotypes but did not eliminate the difference between the obese yellow and lean pseudoagouti and black mice. Interpretation of the available data suggests that no direct relationship exists between the level of hepatic glutathione S-transferase activity and the enhancement of tumor formation in yellow Avy/a mice. Several inbred mouse strains and F-1 hybrids were also screened for this enzyme activity. No strain differences were found but sex differences within different inbred strains were not uniform. In the AE and YS strains and their F-1 hybrid enzyme activity was higher in female than in males. In contrast, BALB/c and VY strain males had higher enzyme activity than the corresponding females.
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PMID:Hepatic glutathione S-transferase activity in mice: effects of Avy/-genotype, obesity, lindane treatment, and sex. 241 15

Maturity-onset obesity and elevated circulating insulin levels are characteristic of some, but not all, mice bearing the viable yellow mutation (Avy) at the agouti locus. The expression of the Avy/a genotype in individual mice, which become obese and which remain lean is determined during prenatal development by as yet unidentified conditions in the dam's reproductive tract. One Avy/a phenotype is identified by a mottled yellow coat and characterized by adult obesity, elevated circulating insulin levels, and impaired glucose tolerance. These mice are notably more susceptible to hyperplasia and neoplasia. The alternative Avy/ a phenotype has a pseudoagouti coat, remains lean, is normoinsulinemic and normoglycemic, and in numerous other characteristics resembles congeneic lean black (a/a) littermates. Obese mottled yellow and lean pseudoagouti Avy/a mice differ in capacity to support the growth of ascites cells, in the growth response to castration, and in hepatic glutathione S-transferase activity, erythrocyte fragility, immune function, and susceptibility to Plasmodium yoelii pathogenesis. Our working hypothesis is that the constellation of characteristics, except coat color pattern, which differentiate the obese yellow mice from their lean littermates, is largely a consequence of the elevated circulating insulin levels that induce increased lipogenesis and decreased lipolysis, increased DNA and protein synthesis, increased mitosis in sensitive tissues, and increased proliferation of transformed cells.
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PMID:Prenatal determination of obesity, tumor susceptibility, and coat color pattern in viable yellow (Avy/a) mice. The yellow mouse syndrome. 373 4

To assist in defining the mechanism(s) by which the activity of hepatic glutathione S-transferase (GST) is decreased in obese rodents, the cytosolic concentrations of individual GST isozymes were determined by high-performance liquid chromatography. For this purpose, liver cytosols from 8- and 16-week-old obese yellow Avy/a and lean black a/a male and female mice of the inbred VY/WffC3Hf/Nctr-Avy strain were assayed. Obese yellow males contained less hepatic GT-9.0 than lean black males; however, there were no differences between the obese and lean females. GT-9.0 concentration, which is induced by testosterone, was several-fold higher in males than in females, regardless of genotype or body weight. No differences in concentrations of other isozymes were detected. Hepatic GST activity towards 1-chloro-2,4-dinitrobenzene was significantly higher in lean males than in obese males; however, there were no differences between obese and lean females. Lean males had higher activity than lean females; but obese males and females had similar enzyme activities. These changes in enzyme activity can be accounted for by the changes in GT-9.0 concentration measured by HPLC. Lung and testes cytosols were also assayed for GST isozyme concentrations. No differences in any isozyme concentration were found between the sexes or the genotypes in the lung or between genotypes in the testes.
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PMID:Glutathione S-transferase activity and isoenzyme concentrations in obese Avy/a and lean a/a mice. 810 70

The effect of genetic obesity and phenobarbital treatment on hepatic conjugation pathways was evaluated in the obese Zucker rat. Acetaminophen pharmacokinetic parameters were examined in vivo after a 30-mg/kg acetaminophen intravenous bolus dose in the presence and absence of phenobarbital treatment. Glucuronidation and glutathione conjugation pathways were studied in vitro in obese and lean Zucker rats after phenobarbital treatment. Obese Zucker rats demonstrated a higher glucuronidation capacity as evidenced by a higher formation clearance of acetaminophen glucuronide and greater UDP-glucuronosyltransferase (UDPGT) activity toward acetaminophen and p-nitrophenol compared with lean controls. Sulfate and glutathione conjugation pathways were not affected by genetic obesity. Obese Zucker rats possessed a higher total hepatic glutathione content due to greater liver weight. Phenobarbital treatment enhanced glucuronidation of acetaminophen and structurally related compounds (i.e., p-nitrophenol) similarly in both phenotypes, but the treatment failed to induce morphine UDPGT in the obese Zucker rat. No effect of phenobarbital was observed on sulfate conjugation, gamma-glutamyl cysteine synthetase activity or hepatic glutathione content in obese or lean Zucker rats. Similar increases in glutathione transferase activities were observed in animals of both phenotypes after phenobarbital treatment. This study demonstrates that glucuronidation is enhanced in genetically obese rats, whereas phenobarbital causes normal induction of several enzymes of the glucuronidation and glutathione conjugation pathways in the obese Zucker rat. However, morphine UDPGT was not induced by phenobarbital, suggesting that obese Zucker rats may possess a defect in the induction of this enzyme similar to that already described for the CYP2B gene in this strain.
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PMID:Effect of genetic obesity and phenobarbital treatment on the hepatic conjugation pathways. 851 12

Leptin is a hormone that is secreted by adipocytes and regulates body weight through its effect on satiety and energy metabolism. The ob/ob mouse is deficient in this protein and is characterized by obesity and other metabolic disorders. This study investigated the alterations of several hepatic cytochrome P-450 (CYP), conjugation, and antioxidant enzymes in lean and ob/ob mice and the role leptin plays in the modulation of these enzymes. Lean and ob/ob male mice were injected with leptin (100 microg) or PBS for 15 days. Liver microsomes from ob/ob mice, when compared with lean controls, displayed significantly reduced chlorzoxazone 6-hydroxylation activity (27%); however, 7alpha- and 16alpha- testosterone hydroxylation and pentoxyresorufin O-dealkylation activities were significantly higher (47%, 22%, and 39%, respectively). Leptin administration corrected alterations seen with all P-450 activities. Dealkylation of ethoxyresorufin and omega-hydroxylation of lauric acid activities from ob/ob and lean mice were not statistically different; however, leptin exposure significantly increased ethoxyresorufin activity in lean mice (14%) and decreased the activity in ob/ob mice (36%). UDP-glucuronosyl-transferase and glutathione S-transferase activities were not altered. The antioxidant enzymes, catalase (11%) and glutathione peroxidase (26%), as well as glutathione reductase (17%), were lower in the ob/ob mice and leptin treatment corrected these alterations. The results of this study demonstrate alterations in constitutive expression of CYP2B, CYP2E, CYP2A, catalase, glutathione peroxidase, and glutathione reductase in ob/ob mice that were restored to lean control values following leptin treatment. Additionally, CYP3A activity was increased following leptin treatment in ob/ob mice. The mechanism for the observed alterations may be due to direct leptin effects or via indirect alterations in insulin, corticosterone, and/or growth hormone.
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PMID:Effect of leptin on cytochrome P-450, conjugation, and antioxidant enzymes in the ob/ob mouse. 1034 99

Even small increases in the frequency of thrombotic disease in users of OCs have general health impact because of their widespread use, which is currently expanding to potential risk groups. The present investigations were launched to study the effects of OCs containing 20-40 micrograms of EE combined with the latest developed gonane progestogens on biochemical risk markers within metabolic systems involved in the development of arterial thrombotic disease. The studies included evaluation of carbohydrate and lipid metabolism as well as the haemostatic system and were performed in non-diabetic women and in women with IDDM, who are prone to the development of arterial thrombosis. In the evaluation of the carbohydrate metabolism in non-diabetic women, we found no effect on fasting glucose or insulin and no effect on the insulin response to oral glucose in women using monophasic OCs containing EE combined with DSG or GST. This contrasts the evaluation of triphasic OCs containing EE combined with GST or NGT, which increased fasting insulin and reduced insulin sensitivity without affecting the glucose-effectiveness or the beta-cell function. Impaired glucose tolerance developed in 10% of the women after 6 months. These finding suggest that OCs are able to induce a state of insulin resistance, which should be considered in the prescription for women with potential disturbed insulin sensitivity or reduced beta-cell secretory capacity e.g. women with ovarian hyperandrogenism, obesity, previous GDM or perimenopausal women. We found no change in glycaemic control in 22 women with well-regulated IDDM treated with a monophasic combination of EE and GST for one year and none of the women developed microalbuminuria during treatment. In the women with diabetes we observed an increase in fasting levels of triglycerides, a decrease in LDL-cholesterol, and unchanged concentrations of total cholesterol and HDL-cholesterol during treatment. In non-diabetic women treated with the same compound or an OC containing EE and DSG we found similar changes in triglycerides and total cholesterol, but increased levels of HDL-cholesterol and unchanged LDL-cholesterol concentrations. In the women with IDDM there was a negative correlation between daily insulin requirement and HDL-cholesterol before and during treatment, but no other statistically significant correlation between estimates of glycaemic control and lipids and lipoproteins were observed. In the non-diabetic women, changes in the haemostatic system included an increase in the procoagulant factors fibrinogen and Factor VIIc; the concentration of active t-PA increased, mainly because of decreased inhibition by PAI-1. The ratio between molecular markers of the activity of the coagulation system and the efficacy of fibrinolysis was unchanged. This was also found in the women with IDDM, who showed evidence of increased fibrin formation and an attenuated fibrinolytic response during treatment. The regulation of the t-PA/PAI system was studied in non-diabetic women in order to elucidate if the effects of OCs are caused by a direct effect on synthesis or clearance of these variables or if they are secondary to changed insulin sensitivity, as described in individuals with atherosclerosis. We found no indications that insulin resistance is involved in the regulation of t-PA and PAI-1 antigen levels, neither before nor during intake of OCs. We showed, however, that the decreased t-PA antigen concentration observed in OC users is caused by reduced synthesis outside the splanchnic circulation. The studies indicate that low-dose OCs containing newer gonane progestogens are able to induce insulin resistance and to impair glucose tolerance. Lipoproteins were not adversely influenced by the OCs neither in the diabetic nor the non-diabetic women; on the contrary, there was a tendency towards increased plasma levels of HDL-cholesterol and decreased LDL-cholesterol which are associated with a decreased risk of atherosclerosis. The changes observed within the haemostatic system were in accordance with a maintained balance between coagulation and fibrinolysis although the rate of fibrin formation may be increased in the women with IDDM. Irrespective of OC use, the interrelationships between metabolic systems in young non-diabetic women are different from those reported in individuals with atherosclerosis or insulin resistance. The effects of OCs on the t-PA/PAI system seem to be mediated by a direct effect on the vessel wall and not by changes in the hepatic clearance. The present findings were obtained in diabetic women without vascular complications, so the conclusion that women with IDDM can use OCs without metabolic alterations of known clinical significance is therefore restricted to those without evidence of diseased vessels. When evaluating the results obtained in the non-diabetic women, it should be remembered that women with recognised risk factors were excluded. The results may therefore be of limited value when evaluating the risk of arterial thrombosis in predisposed populations. In healthy individuals, the present integrated evaluation of biochemical markers does not indicate an increased risk of arterial thrombosis during use of low-dose OCs containing newer gonane progestogens; thus, the findings are in accordance with the recent epidemiological studies on these compounds. The application of relevant biochemical markers facilitate the understanding of the non-reproductive effects of sex steroids which have increasing importance because of their expanding use, not only as contraceptives, but also in the treatment of benign gynaecological disorders, as hormone replacement therapy and as prophylactic agents against specific degenerative conditions. Moreover, they may prove to be helpful in the future identification of women, who have increased susceptibility to the metabolic effects of sex steroids due to genetic predisposition.
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PMID:Pharmacodynamic effects of oral contraceptive steroids on biochemical markers for arterial thrombosis. Studies in non-diabetic women and in women with insulin-dependent diabetes mellitus. 1189 23

The gene dosage effect of the MC4-R (melanocortin 4 receptor) on obesity suggests that regulation of MC4-R expression and function is critically important to the central control of energy homoeostasis. In order to identify putative MC4-R regulatory proteins, we performed a yeast two-hybrid screen of a mouse brain cDNA library using the mouse MC4-R intracellular tail (residues 303-332) as bait. We report here on one positive clone that shares 63% amino acid identity with the C-terminal part of the mouse attractin gene product, a single-transmembrane-domain protein characterized as being required for agouti signalling through the melanocortin 1 receptor. We confirmed a direct interaction between this ALP (attractin-like protein) and the C-terminus of the mouse MC4-R by glutathione S-transferase pulldown experiments, and mapped the regions involved in this interaction using N- and C-terminal truncation constructs; residues 303-313 in MC4-R and residues 1280-1317 in ALP are required for binding. ALP is highly expressed in brain, but also in heart, lung, kidney and liver. Furthermore, co-localization analyses in mice showed co-expression of ALP in cells expressing MC4-R in a number of regions known to be important in the regulation of energy homoeostasis by melanocortins, such as the paraventricular nucleus of hypothalamus and the dorsal motor nucleus of the vagus.
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PMID:Characterization of a novel binding partner of the melanocortin-4 receptor: attractin-like protein. 1465 15

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that directly modulate gene expression by binding to specific ligands. It has been established that PPARgamma ligands play an essential role in obesity, diabetes, and inflammation. Recently, a great deal of research has focused on the screening of PPARgamma ligands. In this study, both a human peroxisome proliferator-activated receptors gamma2 (PPARgamma2) recombinant protein and a specific monoclonal antibody against PPARgamma2 were produced in order to screen PPARgamma ligands. Analysis of deletion mutants revealed that monoclonal anti-PPARgamma antibody Pgamma48.34A possesses an antigenic determinant in the N-terminal region (31-84 a.a) of human PPARgamma2. The results of Western blot testing revealed that Pgamma48.34A recognized both glutathione S-transferase (GST)- and his-tagged human and mouse PPARgamma recombinant proteins and also identified PPARgamma in adipocytes and mouse tissues. Compared to some commercially available antibodies, this antibody does not bind with skimmed milk or BSA and exhibits a higher degree of specificity. An in vitro binding assay revealed that PPARgamma2 was bound to steroid receptor coactivator-1 (SRC-1) in a dose-responsive manner in the presence of indomethacin, and Pr48.34A was able to detect PPARgamma in a complex consisting of PPARgamma and SRC-1. Using Pgamma48.34A antibody, an enzyme-linked immunosorbent assay (ELISA) system based on the binding between fPPARgamma2 and SRC-1 has been optimized to screen new PPARgamma ligands. This new antibody, Pgamma48.34A, exhibits higher degrees of both specificity and sensitivity against PPARgamma than do other commercial anti-PPARgamma antibody, and may constitute a profound contribution to the screening of PPARgamma ligands as well as the functional study of PPARgamma.
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PMID:Epitope analysis of PPARgamma monoclonal antibody Pgamma48.34A and its application for screening PPARgamma ligands. 1568 Jan 57

Breast cancer is the most frequent cancer in women and represents the second leading cause of cancer death among women (after lung cancer). The etiology of breast cancer is still poorly understood with known breast cancer risk factors explaining only a small proportion of cases. Risk factors that modulate the development of breast cancer discussed in this review include: age, geographic location (country of origin) and socioeconomic status, reproductive events, exogenous hormones, lifestyle risk factors (alcohol, diet, obesity and physical activity), familial history of breast cancer, mammographic density, history of benign breast disease, ionizing radiation, bone density, height, IGF- 1 and prolactin levels, chemopreventive agents. Additionally, we summarized breast cancer risk associated with the following genetic factors: breast cancer susceptibility high-penetrance genes (BRCA1, BRCA2, p53, PTEN, ATM, NBS1 or LKB1) and low-penetrance genes such as cytochrome P450 genes (CYP1A1, CYP2D6, CYP19), glutathione S-transferase family (GSTM1, GSTP1), alcohol and one-carbon metabolism genes (ADH1C and MTHFR), DNA repair genes (XRCC1, XRCC3, ERCC4/XPF) and genes encoding cell signaling molecules (PR, ER, TNFalpha or HSP70). All these factors contribute to a better understanding of breast cancer risk. Nonetheless, in order to evaluate more accurately the overall risk of breast tumorigenesis, novel genetic and phenotypic traits need to be identified.
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PMID:Understanding breast cancer risk -- where do we stand in 2005? 1578 78

This study first examined the pharmacokinetic disposition of GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in rats after i.v. injection. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. The radioiodinated 125I-GST-TatdMt was administered to rats at doses of 9 microg (1640 nCi), 18 mug (3388 nCi), and 35 microg (6420 nCi). Upon administration, the total radioactivity in serum declined bi-exponentially, with the average terminal elimination half-life ranging from 13.7 to 15.7 h. There was a linear relationship between dose and AUC(INF) (r2=1.000) and between dose and Co (r2=0.999). The fraction of administered radioactivity excreted in feces was low (mean range 1.5-2.8%), while the majority of the radioactivity was excreted in urine (mean range 54.9-61.4%). The radioactivity found in the liver, lungs, spleen, and kidneys were higher than in serum, but the tissue-to-serum ratios were relatively low (<1.64). The radioactivity in testes, adipose tissue, heart, and brain was lower than in serum (tissue-to-serum ratios 0.046-0.27). The findings of this study indicate dose-linear pharmacokinetics of 125I-GST-TatdMt in rats over the i.v. dose range studied.
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PMID:Dose-linear pharmacokinetics, tissue distribution, and excretion of a recombinant fusion protein 125I-GST-TatdMt possessing potent anti-obesity activity. 1592 94


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