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B C Eller

Publications and source records attributed to B C Eller.

At least 19 recordsLinked to original sources
PubMed1987

The apparent molecular weight of androgen-binding protein (ABP) in the blood of immature rats differs from that of ABP in the epididymis.

When androgen-binding protein (ABP) in unfractionated immature (20-day old) male rat serum was covalently labeled with the site-specific photoaffinity ligand [3H]17 beta-hydroxy-4,6-androstadien-3-one and analyzed on 5.6% polyacrylamide tube gels containing SDS (SDS-PAGE), a protein of Mr 33,700 +/- 1200 was shown to be specifically labeled. Rat epididymal ABP from unfractionated cytosol analyzed under identical conditions exhibited two androgen-specific peaks of radioactivity, Mr 49,900 +/- 600 and Mr 44,100 +/- 800, which correspond to the previously described subunits of ABP. The apparent molecular weight differences between serum and epididymal ABP were further assessed on preparations of serum ABP that had been partially purified by chromatography on Affi-Gel blue (to remove albumin) and on Sephadex G-150 (to remove other proteins). When these preparations of ABP were photolabeled and analyzed by SDS-PAGE as above, two subunits of Mr 61,700 +/- 1300 and Mr 47,100 +/- 700 were resolved. Serum and epididymal ABP were further purified by androgen affinity chromatography. When these preparations were subjected to SDS-PAGE on slab gels containing 10% polyacrylamide and identified by fluorography of photolabeled ABP or by immunochemical localization following electrophoretic transfer to nitrocellulose, differences in the apparent molecular weight of ABP from the two sources persisted. Immunochemical localization studies on ABPs that had been desialylated with neuraminidase indicated that there was an increased mobility of the subunits, as one would anticipate from removal of carbohydrate. Differences in apparent molecular weight of ABPs from the two sources are likely due to differences in glycosylation.

Affinity Labels↗
PubMed1985

Hormonal effects on the estrogen receptor system in the epididymis and accessory sex organs of sexually immature rabbits.

The epididymis and male accessory sex organs (vesicular gland, prostate, and bulbourethral gland) of sexually immature rabbits contain a functional estrogen receptor system which is regulated in an organ-specific manner by various hormones. In both intact and castrated animals, acute estrogen challenge causes depletion of estrogen receptor from the cytosolic fraction and its appearance in the nuclear fraction of these tissues. A considerable amount of unoccupied nuclear receptor was detected both before and after estrogen challenge. An estrogen-activated, receptor-processing mechanism is operable in these organs since chronic treatment (daily for 14 days) with estradiol benzoate modified the levels of total estrogen receptor, and altered the relative amounts of occupied to unoccupied nuclear receptor present following estrogen challenge. Chronic treatment with estradiol benzoate, Tamoxifen, and testosterone propionate (alone and in combination) had differential, organ-specific effects on the ability of subsequent estrogen challenge to cause accumulation of nuclear receptor. The vesicular gland was the most responsive to estrogen treatment and the bulbourethral gland the least responsive.

Androgens↗
PubMed1985

The ontogeny of biologically active androgen-binding protein in rat plasma, testis, and epididymis.

Androgen-binding protein (ABP) can be detected in the blood of sexually immature male rats by its ability to specifically bind [3H]5 alpha-dihydrotestosterone (5 alpha-DHT). Since the androgen-binding site is functional, we consider this ABP to be biologically active. ABP can be detected (641 +/- 107 ng/ml; n = 5) in plasma by the 15th day of postnatal life, it reaches a maximum concentration (1631 +/- 323 ng/ml; n = 5) on day 20 of age, and is no longer detectable after day 40. ABP can be detected in the testes of all age groups studied (15 days to adult). However, no ABP is detectable in the epididymis until the animals are 25 days old. Plasma ABP comigrates on nondenaturing gels with photolabeled ABP from the adult or immature rat epididymis. Serum that had been treated with Affigel blue to remove albumin and with hydroxylapatite to decolorize it was photolabeled using [3H]17 beta-hydroxy-4,6-androstadien-3-one. Photolabeled serum ABP migrated on polyacrylamide gels containing sodium dodecyl sulfate as 60,000 and 48,000 dalton androgen-specific peaks. In contrast, photolabeled adult epididymal ABP exhibited the 47,000 and 41,000 dalton peaks characteristic of ABP subunits. When photolabeled plasma and epididymal ABP were combined and electrophoresed on the same gel under denaturing conditions, prominent 60,000 and 47,000 dalton peaks were obtained, indicating that the two species of ABP retained their identities when combined. Photolabeled epididymal ABP from 25-day-old rats exhibited similar subunit mol wt in the same ratios as ABP from the adult. When epididymal ABP from the two age groups was combined and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the resulting pattern was identical to that obtained when the samples were run individually, except that there was an increase in peak height. These data indicated that there is no significant difference in the subunit mol wt of epididymal ABP from the two age groups.

Androgen-Binding Protein↗
PubMed1984

The effects of various steroids on testosterone metabolism by the sexually mature rabbit epididymis.

We examined the influences of steroids present in the epididymis on androgen metabolism by epididymal tissue and on the binding of androgen metabolites to the epididymal androgen receptor in castrated adult rabbit epididymides under in vitro conditions. The conversion of [3H]testosterone to [3H]17 beta-hydroxy-5 alpha-androstan-3-one (5 alpha-DHT) and to [3H]5 alpha-androstane-3 alpha (beta), 17 beta-diol was inhibited by unlabeled steroids in the following manner progesterone greater than testosterone greater than estradiol. Unlabeled 5 alpha-DHT did not inhibit [3H]testosterone metabolism indicating that product inhibition is not an important regulatory event. The antiandrogen cyproterone acetate did not inhibit the formation of 5 alpha-reduced metabolites of [3H]testosterone. All of the compounds used inhibited androgen binding to the classically defined cytoplasmic and nuclear androgen receptor.

Animals↗
PubMed1984

Clearance, metabolic fate and tissue distribution of an injected bolus of photoaffinity-labeled rat androgen binding protein.

An injected bolus of tritiated photolabeled rat androgen binding protein (ABP) is cleared from the circulation in a biphasic manner. The rapid component of the clearance curve indicates a clearance half time (t1/2) of 4.24 +/- 0.20 h and the slow component indicates a t1/2 of 13.27 +/- 2.92 h. After injection, photolabeled ABP is rapidly degraded as determined by electrophoresis on polyacrylamide gels containing sodium dodecyl sulfate. This method dissociates ABP into subunits of approximately 48,000 daltons. One-half hour after injection of photolabeled ABP, 90% of the radioactivity migrates as a 20,000- rather than as a 48,000-dalton moiety; at the 24-h point only 20,000- and 16,000-dalton species were detectable. Chromatography of plasma on Sephadex G-150 indicated that, under nondenaturing conditions, radioactivity was still associated with proteins having a molecular weight similar to the native ABP dimer. These results suggest that the dimer is substrate for the proteolytic processes affecting ABP. Small (congruent to 7000 dalton) fragments of ABP could be detected in urine by G-150 chromatography 2 h after injection. The control protein [3H] bovine serum albumin (BSA) was cleared from the blood with a time course identical to that of photolabeled ABP (t1/2's 4.69 +/- 0.09 h and 13.56 +/- 1.03 h). [3H] BSA was degraded to peptides that were similar in size to those formed from photolabeled ABP. The uptake of photolabeled ABP and [3H] BSA by potential target tissues (testis, epididymis and ventral prostate) was equivalent, suggesting that the uptake of ABP was a nonspecific phenomenon rather than a receptor-mediated event. The liver and kidneys contained more radioactivity that did the other tissues and there was a differential uptake and clearance of photolabeled ABP and [3H] BSA by these organs. Whether this difference is related to specific uptake processes or to differences in the size and/or structure of the proteins or other factors remains to be determined.

Androgen-Binding Protein↗
PubMed1983

Identification of cytoplasmic estrogen receptors in the accessory sex organs of the rabbit and their comparison to the cytoplasmic estrogen receptor in the epididymis.

Estrogen receptors are present in cytosol prepared from the accessory sex organs (vesicular gland, proprostate, prostate, bulbourethral gland) of sexually immature and of sexually mature rabbits. The receptor in these organs from animals of both age groups has a sedimentation coefficient of 8-10S on low ionic strength (0.01 M KCl) sucrose gradients. Under high ionic strength (0.4 M KCl) conditions, the receptor sediments at approximately 4S. The cytoplasmic estrogen receptor from the epididymis shows age-dependent changes in its sedimentation coefficient. It is 8S under low ionic strength conditions when prepared from immature rabbits and 4S under identical conditions when prepared from sexually mature animals. Although the dissociation constant of the cytoplasmic estrogen receptor in the immature and mature epididymis and accessory sex organs remains constant during development (approximately 0.1 nM), the number of available cytoplasmic estrogen binding sites declines from about 160 fmoles/mg cytosol protein in the immature rabbit to about 40 fmoles/mg cytosol protein in the adult animal. The estrogen receptor in the accessory sex organs is highly specific, the relative affinities of various potential competitors being: estradiol and estrone = 1, diethylstilbestrol = 0.3, estriol = 0.2, tamoxifen = 0.08, testosterone = 0.0004 and 5 alpha-DHT = 0.00005. Changes with age in the physicochemical characteristics of the estrogen receptor and in the concentration of binding sites suggest that the estrogen receptor may be involved in the development and physiological regulation of the male reproductive tract.

Animals↗
PubMed1983

The effects of estradiol, tamoxifen, and testosterone on the weights and histology of the epididymis and accessory sex organs of sexually immature rabbits.

The effects of estradiol benzoate (EB), testosterone propionate (TP), and Tamoxifen, alone or in combination, on the weight and morphology of the male accessory sex glands were studied in intact and in castrated immature rabbits. TP treatments (2 mg/kg) exerted a stimulatory effect on the glands, resulting in a significant increase in the weight of the epididymis, the proprostate, and the prostate of castrated rabbits, and of the bulbourethral glands of both intact and castrated rabbits, and in marked morphological changes in all the glands. the epithelium was stimulated but retained its pseudostratified columnar appearance and resembled more the epithelium of normal mature males than that of age matched controls. The bulbourethral glands were the most responsive and the vesicular gland the least responsive to androgen treatment. The response of the glands to EB (25 micrograms/kg) was characterized by significant weight increases in all the glands of both castrated and intact rabbits, hypertrophy of the musculo-fibrous components and proliferation of the basal layer of the epithelium leading to squamous metaplasia and leukocytic infiltration. Hyperplasia of the fibromuscular stroma was most evident in the cauda epididymidis and in the vesicular gland. Squamous metaplasia and leukocytic infiltration were most evident in the ejaculatory duct and in the structures adjacent to it. The antiestrogen, Tamoxifen (250 micrograms/kg), and TP (2 mg/kg) given in conjunction with EB (25 micrograms/kg) tended to reduce the weight increase caused by estrogen, but the decrease was significant in only a few instances. Tamoxifen (250 micrograms/kg) administered alone stimulated the epithelium of the accessory sex glands and induced squamous metaplasia, but did not induce hyperplasia of the fibromuscular stroma. The study demonstrates that accessory sex glands display a consistent pattern of differential sensitivity to both androgens and estrogens and that these hormones exert their action on different cell types within the organ.

Animals↗
PubMed1982

Some physicochemical characteristics of photoaffinity-labeled rabbit androgen-binding protein.

Photoaffinity-labeled androgen-binding protein (ABP), present in cytosol prepared from the caput epididymidis of intact sexually mature rabbits, was produced using 17 beta-hydroxy-[1,2-3H]4,6-androstadien-3-one (delta 6-testosterone). Photo-labeled ABP could not be distinguished from unlabeled ABP by gel filtration chromatography, electrophoresis on nondenaturing polyacrylamide gels, or sucrose gradient ultracentrifugation. Rabbit ABP was found to have a sedimentation coefficient of 4.6S and a Stokes radium of approximately 45A. Based on these parameters, its native molecular weight was calculated to be approximately 86,300. A model of ABP as a prolate ellipsoid having an axial ratio of 10 is consistent with its frictional ratio of 1.555. When photolabeled rabbit ABP was examined on polyacrylamide gels containing sodium dodecyl sulfate, two androgen-specific peaks of approximately 52,000 and approximately 48,000 daltons were detected. Both peaks contained approximately the same amount of radioactivity. When photolabeled ABP was treated with the cross-linking reagent disuccinimidyl suberate before electrophoresis on gels containing sodium dodecyl sulfate, an additional androgen-specific peak corresponding to approximately 100,000 daltons was obtained. We interpret this peak to represent dimers of the lower molecular weight species. The 52,000- and 48,000-dalton subunits were observed regardless of whether the proteins were treated with 2-mercaptoethanol, indicating that the monomers are not linked by disulfide bonds.

Affinity Labels↗
PubMed1982

Some physicochemical characteristics of photoaffinity-labeled rabbit testosterone-binding globulin.

Photolabeled testosterone-binding globulin (TeBG), obtained from the plasma of sexually immature male rabbits, was produced using 17 beta-hydroxy-[1,2-3H]4,6-androstadien-3-one. Photolabeled TeBG could not be distinguished from unlabeled TeBG by gel filtration chromatography, electrophoresis on nondenaturing gels, or sucrose gradient ultracentrifugation. Rabbit TeBG had a Stokes radius of approximately 45 A and a sedimentation coefficient of approximately 4.6S. Based on these parameters, its native molecular weight was calculated to be approximately 78,000. The frictional ratio of rabbit TeBG was found to be approximately 1.6. When photolabeled TeBG was examined on polyacrylamide gels containing sodium dodecyl sulfate, a single androgen-specific peak of approximately 40,000 daltons was obtained. When photolabeled TeBG was treated with the cross-linking reagent disuccinimidyl suberate before electrophoresis on sodium dodecyl sulfate gels, an additional androgen-specific peak of radioactivity corresponding to approximately 100,000 daltons was obtained. We interpret this peak to represent oligomers of the TeBG subunits. The 40,000-dalton subunit was obtained regardless of whether the proteins were treated with 2-mercaptoethanol, indicating that the monomers are not linked by disulfide bonds.

Affinity Labels↗
PubMed1979

The presence of a cytoplasmic estrogen receptor in sexually mature rabbit epididymides: comparison with the estrogen receptor in immature rabbit epididymal cytosol.

Cytosol prepared from epididymides of castrated adult rabbits contains an estrogen-specific binding component that sediments in the 4--5S region on 0.01 M KCl sucrose gradients. The estrogen-specific binding component is not detectable on sucrose gradients unless the cytosol-[3H]estradiol mixture is first extracted with charcoal to remove uncomplexed and rapidly exchangeable ligand from the sample. The macromolecular bound [3H]estradiol that remains after charcoal extraction dissociates from the receptor with a dissociation half-time of greater than 24 h and is of high affinity (Kd = 6.5 +/- 0.9 X 10(-9) M). The estrogen receptor in the adult rabbit epididymis can also be demonstrated when charcoal-extracted samples are chromatographed on Sephadex G-200. Using this system, the major estrogen-specific binder has an apparent molecular weight of less than 200,000. In contrast, the epididymal estrogen receptor in sexually immature rabbits sediments as an 8S species on low salt gradients and has an apparent molecular weight of 200,000 or greater when assessed by chromatography on Sephadex G-200. The estrogen receptor in both age groups is distributed along the length of the epididymal duct. The highest concentration of the cytoplasmic receptor in both mature and immature rabbits is in the cauda epididymidis. The age-dependent changes in the amount of the receptor suggest that it may be involved in maturational changes in the epididymis. The alterations in the physicochemical properties may reflect physiological changes in the epididymis or in the endocrine status of the animal.

Aging↗
PubMed1977

High affinity estrogen binding by rabbit liver.

Macromolecular binding components for [3H]estradiol-17beta are present to cytosol prepared from rabbit liver. When cytosol from sexually mature male liver was incubated with [3H]estradiol and analyzed for binding on low ionic strength sucrose gradients, two peaks of binding activity were detected. One peak had a sedimentation coefficient of 4--5 S and the other had a sedimentation coefficient of 8--9 S. The two components differed from each other regarding steroid specificity and various physiocochemical parameters. [3H]estradiol binding to the 4--5 S component was not inhibited by estrogens, 5alpha-dihydrotestosterone, progesterone or cortisol. Binding to this component did not appear to be saturable and label was rapidly stripped from it by charcoal. Estradiol binding to the 8--9 S component was estrogen specific, saturable and of high affinity. The specific binder dissociates on high ionic strength sucrose gradients and sediments as a 4--5 S moiety. The specific binding protein has a Kd of 3.05 . 10(-10) M and a dissociation half-time of 33 h and there are 35.2 fmol of binding sites/mg cytosol protein. Estrogen binders are also present in liver cytosol from sexually mature female and sexually immature male rabbits. During prolonged incubation of [3H]estradiol with mature male liver cytosol at 0--5 degrees C polar metabolites of estradiol are produced.

Animals↗
PubMed1975

Androgen binding to cytosol prepared from epididymides of sexually mature castrated rabbits: evidence for a cytoplasmic receptor.

The presence of androgen-binding activity in cytosol prepared from the major anatomical segments (caput, corpus, and cauda) of the epididymis of castrated sexually mature rabbits has been demonstrated. A portion of this binding activity is likely to be the epididymal androgen receptor. When epididymal cytosol from adult castrated rabbits is analyzed on low-ionic strength (0.01 MKCl) sucrose gradients, two peaks of macromolecular binding could be detected, one congruent to 4.6S and one congruent to 8S. On gradients containing 1.0 M KCl, only one sedimenting form congruent to 4.6S could be demonstrated, suggesting that the 8S component is composed of aggregates. If cytosol was preincubated with labeled androgen, followed by an incubation with unlabeled androgen, and subsequently analyzed for binding on low-ionic strength gradients, only the congruent to 8S peak could be detected, indicating that most of the binding in the congruent to 4.6S region was rapidly dissociable. This suggests that binding in this region was to moieties other than receptor. Since androgen binding proteins (ABP) of testicular origin would have been cleared from the epididymis at the timepoints that we concentrated on for most of these studies, the 4.6S binding probably represents the association of androgen with plasma testosterone binding globulin (TeBG). The binding of androgen to the receptor can be inhibited by cyproterone, while this antiandrogen does not inhibit binding to either ABP or TeBG at the concentration used.

Animals↗