Search results for "diethylstilbestrol"
showing 8 items of 18 documents
Metabolites of diethylstilboestrol induce sister chromatid exchange in human cultured fibroblasts
1979
Diethylstilboesterol (DES) is one of the few substances for which a clear association with carcinogenicity has been established in man. Nevertheless, it is still widely used, mainly as a cheap oestrogen to increase the slaughter weight of beef, but in spite of this it is not known if residues in the meat or metabolites excreted by the cattle are hazardous to man. It is also unknown whether there is a threshold dose below which DES is harmless. A threshold might be expected if a hormonal mechanism of carcinogensis rather than metabolic activation to an electrophically reactive species operats. This possibility was supported by the observations that DES, in contrast to most other carcinogens,…
Endometrial Adenocarcinoma in Syrian Hamsters Treated with Diethylstilbestrol, Tamoxifen and N-Ethyl-Nitrosourea
2006
The synthetic estrogen diethylstilbestrol (DES) causes marked abnormalities in the female hamster genital tract, after either prenatal or postnatal exposure, leading to endometrial hyperplasia and carcinoma. Acting as an initiating event, DES altering uterine development may facilitate the abnormal response of promoting agents. Tamoxifen (TAM) is an antiestrogen that competes for central and peripheral estrogen receptor (ERα). TAM exerts agonistic effects on E-dependent endometrial proliferation. N-ethyl-N-nitrosourea (ENU), a potent mutagenic agent, induces tumors in a variety of organs, predominantly in the peripheral nervous system. To test whether ENU and TAM treatment in a model of hyp…
Age-dependent changes of nuclear envelope protein phosphokinase and protein phosphatase activities. Significance for altered nucleo-cytoplasmic mRNA …
1984
Nuclear envelopes are associated with a protein phosphokinase and a phosphoprotein phosphatase, whose activities are modulated by poly(A) in an opposite manner. The activities of these enzymes were determined in nuclear ghosts from liver and oviduct of quails of different age and of different hormone status. Under optimal conditions, kinase activity was found to increase in immature animals 8-fold in response to diethylstilbestrol; co-administration of progesterone had no marked effect on enzyme activity. After the initial burst, the activity of the enzyme increased only slightly during ageing. Two proteins present in nuclear ghosts of Mr 64 000 and of Mr 106 000 are phosphorylated during t…
Alterations of DNA-dependent DNA polymerase activities in the immature quail oviduct in response to estrogen stimulation.
1975
Administration of diethylstilbestrol, an estrogen analogue, to immature female quails causes an increase of extractable DNA-dependent DNA polymerase activities from the oviduct. At least two forms of polymerases have been determined, a high molecular weight polymerase (210,000 daltons) and a low molecular weight polymerase (34,000 daltons) calculated from column chromatography Sephadex G-200. During the primary hormone stimulation the amount of extractable enzyme reaches a maximum on the fifth day after daily injections of the hormone. In the period of withdrawal the activities decrease and reach values similar to those determined in the unstimulated oviducts. During secondary stimulation t…
Relaxant effect of dopamine on the isolated rat uterus.
1988
The effect of dopamine was studied on the isolated uterus of diethylstilboestrol-treated rats. Dopamine, at concentrations (10(7)-10(-4) M) produced a concentration-dependent relaxation in the K+-depolarized rat uterus. On a molar basis, dopamine was about 500 times less potent than adrenaline in relaxing the uterus, the maximum degree of relaxation obtained with both drugs was the same. Pretreatment of the rats with reserpine (5 mg/kg) did not produce any modification of the dose-response curve to dopamine. Similarly, cocaine (3 x 10(-6) M) failed to modify the relaxant effect of dopamine. The dopamine induced relaxation was inhibited by propranolol (10(-9)-10(-7) M) in a dose-dependent ma…
Poly(adenosine diphosphate-ribose) polymerase in quail oviduct. Changes during estrogen and progesterone induction
1974
Abstract The activities of the following enzymes have been determined in nuclei of quail oviducts in response to exogenous stimulation of the birds with diethylstilbestrol, used as an estrogen analogue and progesterone: DNA dependent DNA polymerase, DNA dependent RNA polymerase I and II and poly(adenosine diphosphate-ribose) [=poly(ADP-Rib)] polymerase. During primary stimulation with the estrogen analogue the activities of the four DNA dependent polymerases increase to about the same degree. Upon withdrawal of the hormones the levels of the enzymes drop to values known from nuclei from unstimulated quail oviducts. The secondary stimulation with the estrogen analogue causes a significant in…
Inducibility of the avidin gene by progesterone is suppressed during estrogen-induced cytodifferentiation.
1992
Abstract We have studied epithelial differentiation of the chick oviduct as induced by diethylstilbestrol (DES) and 17β-estradiol (E 2 ). The proportion of goblet cells in the oviduct was slightly higher after E 2 than after DES treatment. Also avidin induction by progesterone was stronger following DES than E 2 priming. In the estrogen pretreated oviduct epithelium, avidin expression was induced by progesterone in the surface epithelial cells, protodifferentiated gland cells and tubular gland cells, but not in goblet cells. During prolonged estrogen treatment, however, the inducibility of avidin by progesterone ceased in tubular gland cells but not in surface epithelial cells. The estrogen…
DES-polyacetals as polymer therapeutics for the treatment of prostate cancer
2012
Esta tesis se centra en el diseño de nuevos conjugados polímero-fármaco sensibles a pH para usarse como agentes únicos o en terapia de combinación para el tratamiento del cáncer hormono-dependiente, en particular cáncer de próstata. Éstos conjugados se basan en sístemas poliacetalicos previamente descritos en los que el fármaco forma parte de la cadena principal del polímero. En el microambiente tumoral o después de la absorción celular por endocitosis, el descenso del pH encontrado en el compartimiento ácido del endosoma lisosomal, desencadena la degradación del polímero y como consecuencia la liberación del fármaco que se difunde fuera en el citosol. Para el diseño de éstos sistemas, la n…