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R F Aten

Publications and source records attributed to R F Aten.

52 records · Page 3Linked to original sources
PubMed1982

Separation of steroidal estrogens and their major unconjugated metabolites by high performance liquid chromatography.

A high performance liquid chromatographic method is described for the rapid, non-destructive separation of a number of physiologically important steroidal estrogens, including the labile catechol estrogens. This procedures uses a "Diol" column and gradient elution to separate in a single run, estrogens ranging from 2-methoxy estrone, one of the least polar C18 steroids, to estriol, one of the most polar. Simpler, isocratic conditions, are provided for the separation of estrogens of similar polarity. A semi-preparative column of similar composition was used for the purification of samples containing 25 to 50 mg of individual steroids.

Chromatography, High Pressure Liquid↗
PubMed1978

Estrogen receptor in rat liver: translocation to the nucleus in vivo.

Following in vivo ethinyl estradiol (EE2) administration (100 microgram sc) to adult female rats, the estradiol-specific binding sites (ESBS) of liver cytosol were markedly reduced at 30 and 60 min. The reduction at 30 min was to one-quarter of that found in rats treated with vehicle alone. Coincident with this reduction, nuclear ESBS were increased. The ESBS of partially purified cytosol and of dense sucrose-purified nuclei were determined by gel filtration after incubations with tritiated estradiol using exchange assay conditions. An elevated temperature during the exchange assay incubations was necessary to demonstrate most of the ESBS in purified nuclei of EE2-treated rats and suggested that estrogens are attached at these sites. Following administration of 5 microgram EE2, the decrease in cytosol ESBS and the increase in nuclear ESBS were smaller. In contrast, 5 microgram EE2 was as effective as 100 microgram EE2 in substantially increasing the ESBS observed in uterine nuclear fractions. The low level of ESBS found in whole brain purified nuclei was unchanged by 100 microgram EE2 administration. The steroid specificity and proteolytic enzyme sensitivity of the purified nuclear ESBS of treated rats were similar to that of the partially purified cytosol ESBS of rats treated with vehicle alone. The data are consistent with the ESBS being estrogen receptor proteins which translocate from the liver cytosol to the nucleus after estrogen administration in vivo.

Animals↗
PubMed1978

Estrogen receptor in adult male rat liver.

A 30% ammonium sulfate precipitation has previously been utilized to partially purify the estrogen receptor(s) of female rat liver cytosol. This procedure has now been used to fractionate the estradiol-binding sites of adult male rat liver cytosol. The 30% ammonium sulfate precipitation partially purifies a group of estradiol-binding sites which have properties quite distinct from the large number of sites present in male liver cytosol. The partially purified male sites seem to have the same properties as the partially purified female estradiol-binding sites. They seem to be proteins that are estrogen specific and have a high estradiol affinity (Kd = 1 X 10(-10) M) and a low estrogen capacity (2.3 fmol/mg liver). The estradiol-binding sites of prepubescent male rat liver cytosol have also been fractionated by 30% ammonium sulfate precipitation. The redissolved ammonium sulfate precipitates from prepubescent male rat liver cytosol contain fewer estradiol-binding sites then those from adult male or female rats. It seems that adult male as well as adult female rat liver contains estrogen receptors.

Aging↗
PubMed1978

An unusual sex steroid-binding protein in mature male rat liver cytosol.

Mature male rat liver cytosol contains a moderate affinity and capacity estrogen-binding protein in at least a 200-fold higher level than mature female or immature male rat liver cytosol. Binding of estradiol to this protein is very rapid, is stabilized by EDTA, and is inhibited by divalent cations. This is the major binding protein for [3H]estradiol ([3H]E2) in mature male rat liver cytosol, and it has properties clearly distinguishing it from putative liver or uterine estrogen receptors. In addition to binding [3H]E2, this protein seems to rapidly bind a [3H]5alpha-dihydrotestosterone ([3H]DHT) metabolite at the same binding site. The binding of this androgen metabolite is stabilized by EDTA and is inhibited by divalent cations. The binding properties of the [3H]DHT metabolite suggest that these binding sites are not classical androgen receptors. Cytosol binding levels of both the [3H]E2 and the [3H]DHT metabolites change in a similar direction in resonse to endocrine manipulation. The putative liver estrogen receptor level, determined after partial purification (in a redissolved 30% ammonium sulfate-precipitated fraction), seems to change in an opposite direction in response to these same endocrine manipulations.

Aging↗
PubMed1977

Androgen binding in human testis.

Cytosol preparations of human testis contain macromolecules that bind tritiated dihydrotestosterone. Studies of steroid competition, heat sensitivity and dissociation rate constants indicate a similarity to serum testosterone-estradiol-binding globulin. The amount of binding of tritiated dihydrotestosterone is greater than could be explained by contamination of testis by serum.

4-Chloromercuribenzenesulfonate↗
PubMed1973

Penicillin-binding component of Bacillus cereus.

(14)C-penicillin is irreversibly bound by Bacillus cereus 569. Incubation of penicillin-treated cells in a cell wall digestion medium results in solubilization of approximately 60% of the irreversibly bound lable. The extent of the solubilization is the same when cells are prepared by either a cold or 37 C treatment procedure. However, spheroplasts prepared by the cold treatment are leaky. When the resulting spheroplasts are incubated in supplemented medium, reduced rates and levels of penicillinase synthesis, relative to induced whole-cell controls, are observed. Spheroplasts from both cold and 37 C prepared cells exhibit this phenomena, although the spheroplasts from 37 C prepared cells synthesized approximately sixfold higher levels of penicillinase. The size distribution of the label solubilized during the preparation of spheroplasts was examined by using Bio Gel P-150 columns. Although no label appeared in the exclusion volume fractions when the cell wall digest of the 37 C treated cells was chromatographed, approximately 10% of the label from cold-treated cells did appear. These results suggest that the presence of irreversibly bound penicillin is required for the synthesis of induced levels of penicillinase and that the irreversibly bound penicillin can be solubilized as a labile complex with material which is excluded from BioGel P-150. It may be concluded that the penicillin-binding lipoprotein complex which has been previously observed is the penicillin-specific binding site. However, the location of this complex in relation to the cell membrane could not be determined.

Amino Acids↗