Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: DrugBank:APRD00691 (EE2)
 7,802 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzymatic rate assay is described for measuring cholesterol in serum. Cholesterol is analyzed by mixing 5 mul of sample with a reagent consisting of cholesterol esterase, cholesterol oxidase, catalase, acetylacetone, methanol, and hydroxypolyethoxydodecane in a ammonium phosphate buffer at pH 7.0. The rate of increase in absorbance of the dihydrolutidine product is measured at 37 degrees C and 405 nm. The change in absorbance between 4 and 10 min is used to calculate the cholesterol concentrations by using simultaneously determined free cholesterol standards. The change is linearly related to cholesterol concentration up to 4 g/liter. Samples containing bilirubin up to 200 mg/liter, uric acid up to 200 mg/liter, and hemoglobin up to 1 g/liter, or certain drugs (clofibrate, phenobarbital, nicotinic acid, salicylate, Ketochol, and Ovral) gave no interference. Ascorbic acid added to serum caused a positive interference. Lipemic samples gave values that were slightly lower than did the method of Abell et al., used for comparison. Our kinetic assay, compared with the method of Abell et al., the enzymatic assay used with Abbott's Bichromatic Analyzer, and the Technicon SMA 12/60 enzymatic procedure gave correlation coefficients of 0.992, 0.985, and 0.986, respectively.
 ...
PMID:Enzymatic rate method for measuring cholesterol in serum. 1 1

Estradiol binds covalently to normal leukocytes during phagocytosis. The binding involves three cell types, neutrophils, eosinophils, and monocytes and at least two reaction mechanisms, one involving the peroxidase of neutrophils and monocytes (myeloperoxidase [MPO]) and possibly the eosinophil peroxidase, and the second involving catalase. Binding is markedly reduced when leukocytes from patients with chronic granulomatous disease (CGD), severe leukocytic glucose 6-phosphate dehydrogenase deficiency, and familial lipochrome histiocytosis are employed and two populations of neutrophils, one which binds estradiol and one which does not, can be demonstrated in the blood of a CGD carrier. Leukocytes from patients with hereditary MPO deficiency also bind estradiol poorly although the defect is not as severe as in CGD. These findings are discussed in relation to the inactivation of estrogens during infection and the possible role of estrogens in neutrophil function.
 ...
PMID:Estrogen binding by leukocytes during phagocytosis,. 85 96

While steroid response is generally restricted by the availability of steroid receptors, the theoretical limits of the response are not known. We have constructed a series of cell lines that stably express the estrogen receptor (ER) at levels up to 5,000,000 ERs per cell and employed these cells to explore the limits of the estrogen response. Several reporter genes with estrogen response elements upstream of the herpes thymidine kinase promoter showed hyperbolic saturation kinetics with increasing ER. Maximum response was 10 times that seen in cell lines with receptor titers comparable to physiological levels. Half-maximal responses required 500,000 receptors per cell, and cells with 5,000,000 ERs showed greater than 90% maximum induction. Estradiol dose-response studies indicated that the receptors are limiting below 500,000 ERs per cell, but at higher ER titers there are spare receptors. In contrast to most reporters, the widely used reporter pA2-CAT, which has 200 base pairs of Xenopus vitellogenin DNA between the response element and the promoter, showed squelching at ER levels beyond 500,000 per cell. Cell lines that expressed ER above this level activated pA2-CAT with a distorted hormone dependence, where saturating ligand concentrations were inhibitory. All reporters displayed squelching when the ER was provided by transient transfection at a level that we judge is 20,000,000 per cell by extrapolation from the behavior of stable cell lines. These findings suggest that saturation of the cellular capacity to mediate an estrogen response and ER-dependent squelching occur at receptor titers well above those encountered in nature. If current models of steroid hormone action are correct, the findings also imply that estrogen response elements are occupied to very small extents under normal conditions.
 ...
PMID:The limits of the cellular capacity to mediate an estrogen response. 156 62

To study the effect of sex hormones and alcohol on the hepatic activities of alcohol metabolizing enzymes, estradiol or testosterone were administered for 4 weeks to ovarectomized or sham operated adult female rats pair-fed nutritionally adequate liquid diets containing either alcohol (36% of total calories) or isocalorically replaced carbohydrates. Estradiol increased the hepatic activities of alcohol dehydrogenase and catalase in both ovarectomized and sham operated female rats on the control diet, whereas this enhancing property was virtually lost in animals on the alcohol diet. The hepatic activities of the microsomal ethanol-oxidizing system remained unaffected under these experimental conditions irrespective of the diet used. Testosterone increased the hepatic activities of the microsomal ethanol-oxidizing system and of catalase and decreased the alcohol dehydrogenase activity in female rats on the control diet, but these changes were either not reproducible or markedly reduced in similarly treated female rats fed the alcohol diet. Thus, sex hormones may strikingly influence the hepatic activities of alcohol metabolizing enzymes, but the changes are modulated by prolonged alcohol consumption.
 ...
PMID:Hepatic alcohol metabolizing enzymes after prolonged administration of sex hormones and alcohol in female rats. 293 50

The hypothesis explored in this article states that the control of the proliferation of estrogen target cells is regulated through two steps: the first involves a proliferative event in which estrogens cancel the inhibition exerted by a plasma-borne protein, and the second, an estrogen-induced proliferative shutoff 1. To study these estrogen-mediated events we developed a series of variants of the human breast MCF7 cell line. A first variant was selected by requiring the ancestral MCF7 cells to proliferate initially in Dulbecco's modified Eagle's phenol red-free medium supplemented with 5% charcoal-dextran stripped fetal calf serum; after 4 months, surviving cells were switched to 10% charcoal-dextran stripped human serum. Five months later, a stable cell line was characterized and cloned having a phenotype that allowed for maximal proliferation in charcoal-dextran stripped human serum-supplemented medium (CDHuS) to which no estradiol was added. Estradiol concentrations above 0.3 nM inhibited the proliferation of these cells; this effect was estrogen-specific. These cells are called E8CASS. A second variant derived from E8CASS cells was selected in 5% CDHuS supplemented with 0.3 nM estradiol; the proliferative pattern of these cells was comparable to that of the ancestral MCF7 cells. These revertant cells are called A2E8CASS. All variants and the ancestral MCF7 cells have functional estrogen receptors, as evidenced by the estrogen-induced expression of a pS2-CAT reporter gene. In conclusion, the collected data are compatible with the idea that, in MCF7 breast cells, the estradiol-mediated proliferative component can be segregated from the inhibitory effect also generated by estradiol.
 ...
PMID:Control of cell proliferation of human breast MCF7 cells; serum and estrogen resistant variants. 789 86

A number of studies suggest that an inverse correlation exists between the epidermal growth factor-receptor and the estrogen receptor expression in primary human breast carcinoma as well as in established human breast carcinoma cell lines. Recent studies suggest that the epidermal growth factor-receptor does not regulate the estrogen receptor gene expression. Whether the estrogen receptor regulates the epidermal growth factor-receptor gene expression is not known. We addressed this question by stably transfecting the estrogen receptor cDNA into the estrogen receptor-negative human breast carcinoma cell line MDA-MB-231. Constitutive expression of functional estrogen receptors in the transfectants resulted in increased mRNA levels of both epidermal growth factor-receptor and transforming growth factor alpha. Estradiol treatment of transfected cells, although enhancing transforming growth factor alpha mRNA levels, did not modulate epidermal growth factor-receptor mRNA levels. The estrogen receptor-transfected cells grown in estrogenic regular medium, however, exhibited lower constitutive levels of epidermal growth factor-receptor mRNA than in steroid-stripped medium, suggesting that estrogens coupled with some factors normally present in the regular medium may indeed downmodulate epidermal growth factor-receptor mRNA. Sodium butyrate treatment enhanced epidermal growth factor-receptor mRNA levels in nontransfected cells grown in regular estrogenic as well as in steroid stripped medium. Sodium butyrate enhancement of epidermal growth factor-receptor mRNA levels was completely abolished in estrogen receptor-transfected cells grown in regular estrogenic medium and blunted in steroid stripped medium. Using various epidermal growth factor-receptor gene promoter-CAT constructs in transient transfection assays, we further demonstrate that sodium butyrate enhanced transcription of the epidermal growth factor-receptor gene. The putative sodium butyrate responsive element(s) appears to localize within the proximal 384 bp of the epidermal growth factor-receptor gene promoter region. Although the interactions between estrogen receptor and epidermal growth factor-receptor are rather complex, taken together, our data suggest that estrogen receptor can indeed modulate the epidermal growth factor-receptor mRNA expression.
 ...
PMID:Expression of estrogen receptors in estrogen receptor-negative human breast carcinoma cells: modulation of epidermal growth factor-receptor (EGF-R) and transforming growth factor alpha (TGF alpha) gene expression. 820 Sep 9

Guinea pig endometrial stromal cells were cultured in serum-free medium to assess the effects of growth factors and ovarian steroids on cell proliferation. When the cells were made quiescent by serum depletion, [3H]thymidine incorporation was increased by the addition of insulin plus epidermal growth factor (EGF), reaching a peak after 24 h of stimulation. This effect was dose-dependent. Both factors acted synergistically. Estradiol-17 beta (E2), either alone or with various concentrations of growth factors, had no mitogenic effect. Thus, cell proliferation appeared to be estrogen-insensitive, despite a high level of estrogen receptors (19,000 sites per cell). The integrity of these receptors was checked by transfecting cells with a plasmid containing an estrogen-responsive element linked to a CAT gene: E2-induced CAT activity was reduced by the antiestrogen ICI 164,384. Despite the presence of progesterone receptors, the cells, either primed with E2 or not, were not growth-stimulated by progesterone. E2 had no effect on cells cultured in the presence of dextran-coated charcoal-stripped serum. Thus, whatever the culture conditions, stromal cells with functional estrogen receptors were insensitive to the putative mitogenic effects of E2 and progesterone. However, they were highly responsive to the mitogenic effects of insulin and EGF.
 ...
PMID:Epidermal growth factor and insulin induce the proliferation of guinea pig endometrial stromal cells in serum-free culture, whereas estradiol and progesterone do not. 828 69

Osteoarthritis is a common geriatric disease and estrogen may play an important role in this disease. Estradiol may cause chondrocyte damage as suggested by in vitro and in vivo data. One of the possible mechanisms of estradiol-induced chondrocyte damage was thought to be related to free radicals. Whether catalase, a known free radical scavenger, can prevent estradiol-induced chondrocyte damage was tested using a chondrocyte culture system. The results of this study suggest that catalase can significantly reduce the estradiol-induced damage to chondrocytes. Apparently, catalase alters the molecular structure of estradiol as indicated by the absorption spectrum of estradiol with time. The modified estradiol may decrease its toxicity to the chondrocytes. However, the contents of free radicals in the treated chondrocytes have no significant difference from the untreated control cells. Studies to further investigate the mechanism or prevention of estradiol-induced chondrocyte damage in osteoarthritis are warranted.
 ...
PMID:Catalase prevents estradiol-induced chondrocyte cytotoxicity. 951 95

We compared the effect of estradiol on activator protein-1 (AP-1) activity in estrogen receptor positive (ER alpha+) and estrogen receptor negative (ER alpha-) human breast cancer cell lines transiently transfected with the AP-1-responsive reporter plasmid AP-1-TK-CAT and an ER alpha expression vector. While estradiol increased AP-1 activity in the ER alpha+ cell lines MCF7, ZR75.1, and T47D, it decreased (MDA-MB231 and BT20 cells) or had no significant effect (MDA-MB435 cells) on AP-1-mediated transcription in ER alpha- cells. Estradiol also inhibited AP-1 activity in ER alpha-MDA-MB231 cells stably transfected with ER alpha and in which ER alpha levels are close to those found in MCF7. Use of ER alpha mutant expression vectors demonstrated that the DNA-binding domain of ER alpha was needed for stimulation or inhibition of AP-1 activity by estradiol but suggested that ER alpha binding to estrogen-responsive elements was not required for these effects. Changes in regulation paralleled quantitative and qualitative changes in protein binding to AP-1 sites, as demonstrated by gel shift assay: protein binding was greater and DNA/protein complexes migrated faster for ER alpha--than for ER alpha+ cells. In fact, by Northern blot, a high level of Fra-1 mRNA was found in BT20 and MDA-MB231 cells as compared with ER alpha+ cells, and MDA-MB435 cells showed an intermediary level of expression. The differential expression of Fra-1 in MCF7 and MDA-MB231 cells was confirmed at the protein level by supershift experiments. In addition, overexpression of Fra-1 in MCF7 cells decreased the positive effect of estradiol while inhibition of Fra-1 expression in MDA-MB231 cells, by transient transfection of the Fra-1 antisense expression vector, abolished the negative effect of the hormone. In conclusion, we demonstrated that ER alpha- breast cancer cell lines differ from ER+ cells by a high level of AP-1 DNA-binding activity due, at least in part, to high Fra-1 constitutive expression. High Fra-1 concentration is crucial for the negative regulation of AP-1 activity by estradiol and thus may take part in estradiol-induced inhibition of cell proliferation in ER alpha- breast cancer cells transfected with ER alpha expression construct.
 ...
PMID:FRA-1 expression level modulates regulation of activator protein-1 activity by estradiol in breast cancer cells. 965 2

Prespawning, adult male and female carp, Cyprinus carpio, were intraperitoneally injected with a single dose of 500 microg/kg of 17alpha-ethynylestradiol (EE2). Blood samples were taken and vitellogenin levels were recorded previous to the injection and 8 days afterward. Western blot analysis of plasma VTG showed a marked response in both males (90-fold) and females (67-fold) after EE2 injection. Also, a significant inhibition of the cytochrome P450 monooxygenase system, namely, 7-ethoxyresorufin O-deethylase (EROD) activity, as well as immunodetected CYP1A protein was observed in the EE2-injected fish. Other cytochrome P450 isozymes, such as CYP3A or NADH cyt (b5) reductase, did not indicate any particular trend; whereas NADPH cyt (P450) reductase was significantly induced in EE2-injected animals. Total cytochrome P450, glutathion S-transferase (GST), and total glutathion peroxidase (GPX) fluctuated in a similar manner, but differences among treated and nontreated animals were not statistically significant. UDP glucuronyl transferase (UDPGT), similar to the antioxidant enzymes catalase, superoxide dismutase (SOD), and Se-GPX, progressively decreased in carrier and injected animals in comparison to the controls, although this trend did not reach statistical significance either.
 ...
PMID:Vitellogenin induction and other biochemical responses in carp, Cyprinus carpio, after experimental injection with 17 alpha-ethynylestradiol. 1078 1


1 2 3 4 Next >>