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S Liao

Publications and source records attributed to S Liao.

At least 163 records · Page 9Linked to original sources
PubMed1984

Immunochemical characterization of the androgen-dependent spermine-binding protein of the rat ventral prostate.

A solid-phase radioimmunoassay was developed to measure the level of the androgen-dependent spermine-binding protein (SBP) in the cytosol fraction of the rat ventral prostate during endocrine manipulation. The concentration of SBP and immunologically cross-reacting material (CRM) in the ventral prostate was at least 5000 times higher than the level of CRM detected in rat serum or cytosol from other rat tissues. Cytosol from the ventral prostate of intact rats was separated by DEAE-cellulose chromatography into three major fractions of CRM. One of these fractions corresponded to the elution position of SBP. Cytosol prepared from rats 48 h after castration lacked SBP and one of the two other fractions of CRM. This loss coincided with an increase in CRM in the remaining fraction. No significant difference was detected in the total level of CRM when intact and 48 h-castrated rats were compared. Injection of rats with 5 alpha-dihydrotestosterone (DHT) immediately after castration prevented these changes in the profile of CRM. Several proteins cross-reacting with antibodies to purified SBP were detected in cytosol by using an immunoblot procedure. The highest-Mr band corresponded to SBP. The effect of short- and long-term castration and subsequent DHT treatment on CRM was studied by using the immunoblot technique. Short-term castration (2 days) led to the disappearance of CRM coinciding with SBP (Mr 35 000-38 000) and an increase in smaller forms of CRM (Mr 24 000 and 22 000). Injection of rats with DHT 2 days after castration led to the reappearance of CRM corresponding to SBP, which returned to normal levels within 4 to 5 days of treatment. Long-term castration (up to 14 days) led to a gradual disappearance of all CRM; subsequent DHT treatment led to the reappearance of all forms of CRM and normal levels were attained within 5 days. We have identified SBP and the various forms of CRM as a secretory product of the rat ventral prostate by immunohistochemical staining and by DEAE-cellulose fractionation of prostatic fluid. Prostatic fluid is rich in proteolytic activity and these proteinases may be responsible for processing SBP to small forms of CRM.

Animals↗
PubMed1984

The use of radioactive 7 alpha, 17 alpha-dimethyl-19-nortestosterone (mibolerone) in the assay of androgen receptors.

Tritiated 7 alpha, 17 alpha-dimethyl-19-nortestosterone (DMNT; mibolerone), a synthetic androgen stable to metabolic conversion in the rat ventral prostate, is an excellent radioactive ligand for the quantitation and characterization of androgen receptors in prostate, liver, and cultured cells. DMNT is more receptor-selective than 17 alpha-methyl-17 beta-hydroxy-estra-4,9,11-trien-3-one (R1881); DMNT interacts with glucocorticoid and progestin receptors much less strongly than R1881. Unlike 5 alpha-dihydrotestosterone, DMNT does not bind tightly to testosterone-estradiol binding globulin of human serum. The hydroxylapatite-filter assay we employed can clearly distinguish between DMNT binding to androgen receptors of rat ventral prostate and interaction of DMNT with androgen binding protein of epididymides. The prostate cytosol (3H)DMNT-receptor complex sediments in two forms (4 and 8 S) in a low salt medium. In 0.4 M KCl, both the prostate cytosol and nuclear (3H)DMNT-receptor complexes migrated as 3-4 S components. The formation of both the cytosol and nuclear DMNT-receptor complexes is inhibited by antiandrogens and 17 beta-estradiol.

Androgen-Binding Protein↗
PubMed1984

Analysis of androgen-sensitivity in rat prostate X mouse kidney cell hybrids.

Variant androgen-sensitive cell lines were produced by fusing freshly isolated epithelial cells from the rat ventral prostate with a line of murine renal tumor (RAG) cells. The properties of the cloned lines of the prostate X RAG hybrids can be summarized as follows: (1) the modal chromosome number of the hybrid cell lines ranged from 68 to 176; (2) the cells had doubling times of 7.6-49.5 h; and (3) epitheloid, ameboid and intermediate morphologies were observed among the various lines. The proliferative response of various hybrid lines to treatment with 10 nM 5 alpha-dihydrotestosterone was used to classify the hybrids as either very sensitive (greater than 40% reduction in cell doubling time), sensitive (greater than 10% reduction in doubling time) to androgens, or insensitive (less than 10% reduction in doubling time) to androgens. There was no direct relationship between the androgen-sensitivity of the cells and their androgen receptor content, suggesting that these variant cell lines may be useful for the study of the genetic factors involved in cellular responses to androgens.

Animals↗
PubMed1984

The use of a hydroxylapatite-filter steroid receptor assay method in the study of the modulation of androgen receptor interaction.

Receptors for androgen, estrogen, and glucocorticoid can be assayed by hydroxylapatite adsorption of the radioactive steroid-receptor complex and washing of the adducts on membrane filters mounted on a multiple filter holder. The method is economical, very rapid and sensitive. This new receptor assay method was used to study the modulation of androgen receptor of rat ventral prostate by metal ions, thiols, and ligand structure. The interaction of androgen with the naked receptor is inhibited by 10 microM ZnCl2, CdSO4, or CuSO4 but this inhibition is competed by androgen and is reversed by DTT. The androgen-receptor complex is less sensitive to divalent metal ions but Zn2+, at 3 mM, appears to alter the conformation of the receptor and promote the release of androgen. Certain phenanthrene derivatives exhibited striking structural specificities in their ability to compete with radioactive androgen for binding to the prostate receptor. The results suggest that the receptor has binding preference toward individual ring structure in the steroid.

Animals↗
PubMed1984

Steroid metabolism and binding activity in a murine renal tumor cell line.

The purpose of this study was to partially characterize the steroid binding activity of murine renal tumor cells in continuous culture. The steroid receptor content of a cloned renal tumor cell line (RAG) and a subline RAG-2 was examined by sucrose gradient analysis, hydroxylapatite and dextran-coated charcoal methods. The RAG cells lacked estrogen- and progestin-binding activity, whereas specific 5 alpha-dihydrotestosterone (DHT) and dexamethasone (Dx) binding activities were detected as 8S peaks on low salt gradients. The specificity of DHT binding was examined by sucrose gradient analysis: DHT, R1881 and ORG2058 all completely inhibited [3H]DHT binding whereas diethylstilbestrol and Dx were ineffective. The androgen receptor content of the RAG cells was approx. 15 fmol/mg cytosol protein by the hydroxylapatite-filter assay, with an estimated Kd for methyltrienolone (R1881) of 5 nM at 0 degrees C. Scatchard analysis of [3H]Dx binding by RAG cytosol showed a Kd of 6 nM for Dx and 44 nM for corticosterone at 0 degrees C. Glucocorticoid receptor levels were estimated to be 182 fmol/mg cytosol protein by dextran-coated charcoal assay. Metabolism of [3H]testosterone and [3H]DHT by RAG cells was examined 1, 4 and 6 h after exposure to labeled hormone. Radioactive DHT was the primary intracellular metabolite recovered after exposure to [3H]testosterone. There was little conversion of DHT to androstanediol.

Animals↗
PubMed1983

Polyamines inhibit phospholipid-sensitive and calmodulin-sensitive Ca2+-dependent protein kinases.

Effects of polyamines on various protein kinases were investigated. It was found that both phospholipid-sensitive Ca2+-dependent protein kinase and myosin light-chain kinase (a calmodulin-sensitive species of Ca2+-dependent protein kinase) were inhibited to different degrees by polyamines, with an approximate order of inhibitory potency of spermine = 1, 12-diaminododecane greater than spermidine = 1, 10-diaminodecane much greater than cadaverine = putrescine. Kinetic analysis revealed that spermine inhibited the phospholipid-sensitive enzyme non-competitively with respect to Ca2+ (Ki = 0.84 mM) and phosphatidylserine (Ki = 0.90 mM); it also inhibited myosin light-chain kinase non-competitively with respect to Ca2+ (Ki = 1.82 mM) and calmodulin (Ki = 2.73 mM). 1, 12-Diaminododecane, in comparison, inhibited the phospholipid-sensitive enzyme competitively with respect to Ca2+ (Ki = 0.45 mM) and phosphatidylserine (Ki = 0.50 mM); it also inhibited myosin light-chain kinase competitively with respect to calmodulin (Ki = 0.63 mM) but non-competitively with respect to Ca2+ (Ki = 1.49 mM). Moreover, spermine (0.5 mM) was found to inhibit markedly phosphatidylserine/Ca2+- and calmodulin/Ca2+-stimulated phosphorylation of endogenous proteins in rat brain particulate fraction. All the polyamines tested were practically without effect on cyclic AMP-dependent and cyclic GMP-dependent protein kinases. Polyarginine, like spermine, was found to be a more selective inhibitor of Ca2+-dependent protein kinases, whereas polyglutamate preferentially inhibited the cyclic nucleotide-dependent enzymes. The present results indicated that, in addition to certain lipophilic compounds (such as trifluoperazine, palmitoylcarnitine, adriamycin and naphthalenesulphonamide) and polypeptides with hydrophobic regions (such as melittin and polymyxin B) previously reported, polycationic compounds (exemplified by polyamines) could also inhibit the two classes of Ca2+-dependent protein kinases requiring either phospholipid or calmodulin as a cofactor. Because of the high cellular concentration (up to 10 mM) and the differential effects of polyamines, it is suggested that spermine, and to smaller extents spermidine and putrescine, may be involved in the regulation of certain Ca2+-dependent protein-phosphorylation systems in vivo.

Animals↗
PubMed1982

Intracellular inactivation, reactivation and dynamic status of prostate androgen receptors.

The dynamic status of the androgen receptor in prostate cells was studied by incubation of rat ventral prostate with radioactive 17beta-hydroxy-5alpha-androstan-3-one (5alpha-dihydrotestosterone) in the presence and absence of respiratory poisons and inhibitors of protein and RNA synthesis and also by isotope chasing of the radioactive androgen-receptor complexes. The androgen receptor in the prostate appears to go through a dynamic process of recycling between the cytoplasm and the nucleus as well as an inactivation process. The radioactive androgen-receptor complex, however, is maintained at a constant level for at least 2h during incubation at 37 degrees C, even in the absence of new protein synthesis, suggesting that early androgen actions may not require a depletion of a major portion of cellular receptor. In the presence of 2,4-dinitrophenol, the androgen receptor is rapidly deactivated (half life, 2min). The inactive receptor can be reactivated efficiently by an energy-dependent process, even in the absence of protein synthesis. Receptor binding of androgen and nuclear chromatin binding of the androgen-receptor complex are fast processes; half-maximum binding can be achieved within 1 and 10min respectively. On the contrary, the overall process of the release of the receptor complex from nuclear chromatin and its reappearance in the cytosol fraction has a long half life of about 70min. This slow process may reflect the involvement of the steroid-receptor complex in a time-consuming mechanism that is essential for hormone responses. Actinomycin D can increase the nuclear receptor level by 50% or more. This increase is not due to a decrease in the rate of receptor release from nuclei or to inhibition of DNA degradation by the antibiotic.

2,4-Dinitrophenol↗
PubMed1982

Treatment of herpes virus infections in immunocompromised patients with acyclovir by continuous intravenous infusion.

Sixteen immunocompromised patients with herpes virus infections were treated for three to five days with continuously administered intravenous acyclovir. Patients received initial acyclovir infusions over 5 minutes in dosages ranging from 1.5 to 5.0 mg/kg followed by continuously infused acyclovir at 7.2, 14.4, 21.6, 28.8, 36.0, or 43.2 mg/kg per day. The mean serum plateau levels of acyclovir determined by radioimmunoassay ranged from 4.1 microM for the 7.2 mg/kg per day dosage to 36.6 microM for the 43.2 mg/kg per day dose. A mean of 75 percent of acyclovir administered was recovered in the urine of patients treated. Eleven of 13 patients with varicella-zoster virus (VZV) infections had no new vesicle formation after three days of acyclovir treatment and all patients ceased to have new vesicles after five days of therapy. For the nine patients from whom complete viral cultures were available, six ceased to shed virus at three days, and viral shedding ceased by five days in all patients treated with acyclovir. No clinical or laboratory adverse reactions were associated with acyclovir therapy. These data suggest that acyclovir given by continuous intravenous infusion may be useful in the treatment of herpes virus infections in immunocompromised patients.

Acyclovir↗
PubMed1982

Prostate alpha-protein. Isolation and characterization of the polypeptide components and cholesterol binding.

alpha-Protein, a major glycoprotein in the cytosol fraction of rat ventral prostate, has a molecular weight of about 50,000 and can be dissociated, by sodium dodecyl sulfate, into two different subunits (A and B). alpha-Protein has three different polypeptide components with apparent molecular weights of 10,000 (I), 14,000 (II), and 15,000 (III). These components were purified to homogeneity and their amino acid compositions were determined. Subunit A is composed of Components I and III, whereas subunit B is composed of Components II and III. Carbohydrate was detectable only on Component III. Component III isolated from subunit A and Component III isolated from subunit B appear to be identical. The purified alpha-protein contains 0.7-1 mol of cholesterol/mol of protein. If cholesterol was removed by acetone, about 1 mol of 5 alpha-dihydrotestosterone or pregnenolone could bind to 1 mol of alpha-protein. In the presence of 2 mM ZnCl2, alpha-protein can form dimers and tetramers. In cell-free systems, alpha-protein can inhibit binding of the androgen-receptor complex to nuclear chromatin and also can promote the release of the complex already bound to chromatin. This effect is due to polypeptide Component I.

Amino Acids↗
PubMed1982

Prostate alpha-protein. Complete amino acid sequence of the component that inhibits nuclear retention of the androgen-receptor complex.

The amino acid sequence of Component I of alpha-protein, a glutamic acid-rich protein, is presented. Component I is a single chain polypeptide which consists of 88 amino acid residues with a molecular weight of 10,191. Component I has the amino acid composition Lys6, His, Arg2, Cys3, Asp5, Asn2, Thr3, Ser4, Glu13, Gln3, Pro3, Gly2, Ala6, Val9, Met4, Ile4, Leu8, Tyr6, Phe3, Trp, with serine and asparagine as NH2(-) and COOH-terminal amino acids, respectively. Automated sequences analysis of the whole protein, as well as characterization of the peptides obtained from trypsin, chymotrypsin, and staphylococcal protease digestion and cyanogen bromide treatment, led to the elucidation of the complete primary structure of this protein.

Amino Acid Sequence↗
PubMed1979

Androgen-sensitive spermine-binding protein of rat ventral prostate. Purification of the protein and characterization of the hormonal effect.

The rat ventral prostate contains a cytosol protein that can non-covalently bind spermine much more tightly than spermidine or other natural diamines. The protein has been purified to homogeneity, as judged by electrophoresis in urea- and sodium dodecyl sulphate-containing polyacrylamide gels. The protein, with or without spermine bound to it, sediments at 3 S in a sucrose gradient with or without 0.4 M-KCl. The molecular weight of the protein is about 30 000. Each molecule of the binding protein can bind one molecule of spermine. In the prostate of rats injected with cycloheximide, the protein appears to have a half-life of about 3.5 h. The spermine-binding activity of an acidic fraction obtained by DEAE-cellulose chromatography of the prostate cytosol proteins is reduced by about 40--60% within 20--40 h after castration. This effect is reversed very rapidly within 15--30 min by intraperitoneal injection of 5 alpha-dihydrotestosterone. The hormonal effect is androgen-specific and is not mimicked by dexamethasone or oestradiol-17 beta. The androgen effect was reduced significantly when rats were injected with cycloheximide or actinomycin D, suggesting that the acidic protein may be one of the earliest proteins induced by androgen in the rat ventral prostate.

Animals↗