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Biomedical subjects

K Pollow

Publications and source records attributed to K Pollow.

At least 55 records · Page 3Linked to original sources
PubMed1990

Binding of oral contraceptive progestogens to serum proteins and cytoplasmic receptor.

Some progesterones widely used in oral contraceptives are characterized at the level of high-affinity receptor binding as well as binding to sex hormone-binding globulin and corticosteroid-binding globulin. With regard to binding to sex hormone-binding globulin, gestodene, levonorgestrel, and to a lesser extent 3-ketodesogestrel (which is only formed from the prodrug desogestrel in the body), show a behavior that is manifested in the relatively high affinity to sex hormone-binding globulin, whereas desogestrel and norgestimate do not display any measurable affinity for this specific steroid-binding serum protein. Furthermore, levonorgestrel and gestodene dissociate very much more slowly from the binding sites of sex hormone-binding globulin than 3-ketodesogestrel. A natural affinity of all these synthetic progestogens tested for corticosteroid-binding globulin could not be established. Gestodene, levonorgestrel, and 3-ketodesogestrel bind to the progesterone, glucocorticoid, and androgen receptor with high affinity, apart from slight differences, whereas estrogen receptor affinity could not be demonstrated in any of the progestogens investigated. In relation to aldosterone, the relative binding affinity values of gestodene, levonorgestrel, and the natural progestogen progesterone are relatively high, whereas 3-ketodesogestrel does not display any measurable affinity for this receptor species.

Animals↗
PubMed1990

Lack of binding of gestodene to estrogen receptor in human breast cancer tissue.

Competition studies with progesterone and estradiol receptors of human myometrial tissue as well as of mammary cancer tissue showed that gestodene bound with high affinity to the progesterone receptor, as did other synthetic and natural progestogens. However, gestodene did not bind to the estradiol receptor. The relative binding affinities of all tested synthetic and natural ligands showed no organ-specific differences and no differences between neoplastically transformed and normal tissues.

Binding, Competitive↗
PubMed1990

[Steroid hormone receptor status of colorectal cancers].

Tumor samples of 26 consecutive colorectal carcinomas were studied for the presence of steroid hormone receptors for estrogen and progesterone. In all cases, the estradiol receptor binding capacity was below 2 fmol/mg cytosol protein. In 4 of 26 samples, progesterone receptor levels from 13 to 23 fmol/mg cytosol protein were observed. Because of the identification of steroid receptors in some cases and single reports in literature about tumor regression under hormone therapy of colorectal carcinoma, further investigations seem indicated to study the hormone sensitivity of colorectal carcinoma.

Aged↗
PubMed1989

One millisecond of light suffices to suppress nighttime pineal melatonin synthesis in rats.

The effect of a single high-intensity light pulse with a duration of 1 ms on nighttime pineal activity of male Sprague-Dawley rats was investigated. 10 minutes after light exposure pineal N-actyltransferase activity and melatonin content were significantly reduced. These results show that the rat pineal is capable of responding to very short light flashes of high intensity.

Acetyltransferases↗
PubMed1989

Medroxyprogesterone acetate: steady-state pharmacokinetics bioequivalence of two oral formulations.

Two micronized oral formulations of medroxyprogesterone acetate (MPA) (Farlutal and Clinovir) were compared in order to evaluate their relative bioavailability. Sixteen female patients with metastatic breast cancer were entered in a randomized cross-over study on 500-mg MPA tablets repeatedly administered (twice daily for 20 days). At the steady state, similar mean +/- SD serum levels of MPA were obtained (131 +/- 44 ng/ml for Farlutal and 136 +/- 45 ng/ml for Clinovir) and the two formulations proved to be bioequivalent (confidence interval at a significance level of 0.95 = 93%-107%).

Administration, Oral↗
PubMed1989

3H-ZK 98,734, a new 11 beta-aryl substituted antigestagen: binding characteristics to receptor and serum proteins.

Recently, in the laboratories of Schering in Germany a competitive progesterone antagonist, ZK 98,734, was synthetized, which is characterized by a similar antigestagenic activity as RU 38,486, synthezised by Roussel-Uclaf in France, as assessed by inhibition of nidation tests in rats and guinea pigs. However, this compound has a substantially lower antiglucocorticoid activity measured in cell culture systems than RU 38,486. The purpose of this study was to present a comparison of biochemical and physical properties of the complexes formed by the human uterine progesterone receptor with 3H-ZK 98,734 on one hand and with other well-established progestins on the other hand. ZK 98,734 competed in the same order of magnitude as progesterone or RU 38,486 for the 3H-R5020 binding site of progestin receptor, whereas R5020, Org 2058 or progesterone were unable to compete against 3H-ZK 98,734. This apparent contradiction could be explained by means of FPLC-chromatography and sucrose density centrifugation technique. FPLC-chromatography with an anion exchange column (Mono Q, Pharmacia, Uppsala, Sweden) showed that 3H-ZK 98,734 forms at least two stable complexes with uterine cytosol, on one hand with serum albumin, which presents almost 90% of bound radioactivity, and on the other hand with the two native progestin receptor forms, corresponding to 4S and 8S receptor forms in sucrose density gradient analysis. Competition experiments in liver cytosol of adrenalectomized rats with increasing concentrations of unlabeled ligands other than dexamethasone showed that ZK 98,734, RU 38,486 and cortisol displaced 3H-dexamethasone efficiently from the binding sites in the cytosol. Furthermore, results concerning the specificity of 3H-cortisol binding to serum proteins in diluted pregnant serum demonstrated that ZK 98,734 did not compete with 3H-cortisol for serum binding.

Animals↗
PubMed1989

Gestodene: a novel synthetic progestin--characterization of binding to receptor and serum proteins.

Gestodene, 17 alpha-ethinyl-13-ethyl-17 beta-hydroxy-4,15-gonadien-3-one, is a new orally active progestational agent, which is available for clinical use in oral contraceptives. The aim of the present study is to make a broad characterization of gestodene at the receptor level and to discuss the results in comparison to those of established progestogens. Kinetic studies of 3H-gestodene uptake show a rapid increase in the amount of specific binding during the first three hours. After saturation, the amount of specifically bound 3H-gestodene remained almost constant up to 24 hours at 4 degrees C. The dissociation of 3H-gestodene from the cytoplasmic myometrial progestone receptor, measured by displacement of labeled steroid with dextran-coated charcoal treatment at 4 degrees C at various times, showed a biphasic or two-component first order dissociation curve. As anticipated, sucrose gradient centrifugation analysis of the 3H-gestodene-labeled cytosol of human myometrial tissue showed that the gestodene binding components sedimented in the 4S and 8S region. A 200-fold molar excess of nonradioactive gestodene reduced only the 8S binding of 3H-gestodene. 4S binding of 3H-gestodene was not reduced, which indicate the existence of a second high capacity binding component. In biological test systems, such as the Clauberg test or Kaufmann test, gestodene has proved to be a very effective progestogen. Among nortestosterone derivatives it is one of the most potent and resembles progesterone biologically in its progestogenic effects. This biologically identical gestagenic activity of gestodene and progesterone is reflected by a very similar behavior in vitro in terms of binding to progesterone receptors of human uterus cytosol. Furthermore, competitive studies indicated that gestodene like other synthetic progestagens also displays some affinity for androgen and glucocorticoid receptors but no measurable affinity for the estrogen receptor. Remarkable is the high binding affinity of gestodene to the binding sites of the mineralocorticoid receptor of rat kidney with a RBA value of 350% compared to aldosterone.

Animals↗
PubMed1989

An enzyme-linked immunosorbent assay (ELISA) for human corticosteroid-binding globulin.

A specific and sensitive enzyme-linked immunosorbent assay (ELISA) of the "sandwich-type" for human corticosteroid-binding globulin was developed. A polyclonal rabbit anti-CBG antibody is immobilised to a microtitre plate. Following incubation of standards and samples a second monospecific rabbit anti-CBG antibody, labelled with alkaline phosphatase, is added. After colour development the microtitre plate is read at 405 nm wavelength. The assay shows good agreement to CBG binding capacity assay and commercially available RIA.

Antibody Specificity↗
PubMed1989

Development and validation of a radioimmunoassay for serum melatonin.

A radioimmunoassay using N-[3-(4-hydroxy-3-[4-hydroxy-3- [125I]iodophenylpropionyl)]-5-methoxytryptamine as tracer for determination of melatonin in the serum of different species is described. Melatonin antisera were raised in rabbits by immunization with a bovine serum albumin conjugate of N-[3-(2-aminoethyl)-5-methoxy indole] hemisuccinamide. A single high affinity, specific antiserum was obtained. In contrast to previous studies, the tracer was synthesised in one step in the absence of water, giving an excellent yield of highly pure product. No chromatographic purification step was needed. Polyethylene glycol in combination with goat antirabbit immunoglobulins was used to separate bound and unbound tracer. Sera were delipidized with Lipoclean prior the extraction of melatonin with diethyl ether. This sample preparation allows the determination of melatonin in the presence of widely varying amounts of lipids in human, rat and hamster serum. Using this extraction procedure, the sensitivity of the radioimmunoassay was approximately 1 ng/l of serum. Dilutions of sera and of synthetic melatonin gave the same parallel response in the radioimmunoassay. High performance liquid chromatography analysis of a serum extract showed only one immunoreactive peak co-eluting with synthetic melatonin. Characteristic diurnal rhythms of melatonin were observed in all species. All assay components including standards and serum controls are stable for at least 1 year at 4 degrees C, thus facilitating the determination of melatonin in a routine laboratory.

5-Methoxytryptamine↗
PubMed1989

Serotonin and melatonin contents in the pineal glands from different stocks and strains of laboratory rats.

In the present study the pineal gland was examined in 2 outbred stocks and 6 inbred strains of rats some of which were pigmented to varying degrees, to see whether inbreeding affects the variability and whether differences exist between albino and pigmented rats. The animals were kept under 12 h light: 12 h darkness (12 L:12 D) and killed 7 h after the onset of light and darkness, respectively. The parameters examined were pineal protein content, serotonin and melatonin levels and hydroxyindole-O-methyltransferase (HIOMT) activity. All the parameters examined revealed interstrain differences, independently of whether the data were expressed per pineal or per mg protein. The variation coefficients for the various parameters were relatively high. They were mostly smaller when the data were expressed per pineal rather than per mg protein. No striking differences existed between the variation coefficients in inbred and outbred rats. When pineal size and the melatonin-related parameters expressed per pineal were used to assess the melatonin-synthesizing capacity of the pineal glands, it was found that the outbred Wistar and Sprague-Dawley rats and the inbred LEWIS-derived (LEW/Han) rats, all of which were albinos, had the most active pineals. Intermediate activity was noted in the hooded E3/Han and BDE/Han and the albino BDII/Han rats. The smallest and least active pineals were found in the totally pigmented BN/Han and DA/Han rats. The results taken together show that different stocks and strains exhibit significant differences in pineal size and melatonin-forming capacity. Albino rats appear to have larger and more active pineals than pigmented rats.

Acetylserotonin O-Methyltransferase↗
PubMed1988

Preparation of electrophoretic variants of corticosteroid-binding globulin (CBG) using liquid liquid partition chromatography.

Human corticosteroid-binding globulin (CBG) was purified to homogeneity by application of three different chromatographic methods. After fractionation of pregnancy serum with ammonium sulfate the 80%-pellet was used for affinity chromatography based on tresyl activated Sepharose (Pharmacia, Uppsala, Sweden). The affinity eluate was injected into a Mono Q anion exchange column (Pharmacia). Fractions containing CBG were finally purified by liquid liquid chromatography on LiParGel 750 (Merck, Darmstadt, F.R.G.). The purified protein was characterized by IEF and PAGE. This paper describes a method for the chromatographic separation of the two variants of CBG without a loss of binding activity towards steroids for each of the two characteristic bands of this protein.

Chromatography, Affinity↗
PubMed1988

Day/night serotonin levels in the pineal gland of male BALB/c mice with melatonin deficiency.

Studies from another laboratory have shown that several strains of laboratory mice have a genetic defect for melatonin synthesis. In non-deficient species, melatonin synthesis undergoes a typical, beta-adrenergically regulated day/night rhythm with low melatonin levels during daytime and high levels at night, the precursor serotonin showing an inverse behaviour. This study examines whether a day/night rhythm of pineal serotonin levels exists in melatonin-deficient male BALB/c mice. Mice kept under a lighting schedule of 12 h light (lights on at 07.00 h) and 12 h dark were killed at 13.00 and 01.00 h, respectively. Serotonin amounted to 12-15 ng/pineal and did not show regular day/night differences. Administration of the beta-adrenergic agonist, isoproterenol, which is known to affect melatonin synthesis in a number of species, was without effect on pineal serotonin levels. Melatonin and two of the melatonin-forming enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) were below the detection limit in the pineal. It is concluded that in melatonin-deficient BALB/c mice, pineal serotonin synthesis is apparently intact. In BALB/c mice, serotonin synthesis and release do not appear to be directly or indirectly regulated by beta-adrenergic mechanisms.

Acetylserotonin O-Methyltransferase↗
PubMed1987

Application of liquid-liquid partition chromatography in the simultaneous purification of sex-hormone-binding globulin and corticosteroid-binding globulin.

Two human serum proteins, corticosteroid-binding globulin (CBG) and sex-hormone-binding globulin (SHBG), were purified to homogeneity by the application of a combination of three different modes of chromatography. Human pregnancy serum was fractionated with ammonium sulphate. SHBG (50% pellet) and CBG (80% pellet) were then purified by affinity chromatography on tresyl-activated Sepharose with 15-aminopentadecanoic acid (for SHBG) and 1,12-diaminododecane (for CBG) as spacers and 17 zeta-aminoethyl-5 alpha-androstan-3 beta,17-diol (for SHBG) and 17 alpha-hydroxy-4-androsten-3-one-17 beta-carboxylic acid (for CBG) as specific ligands for these two proteins. The eluate was injected into a Mono Q anion-exchange column. Fractions containing SHBG or CBG were finally purified by liquid-liquid chromatography on Lipar-Gel 750. This chromatographic sequence clearly separated SHBG and CBG from other proteins, mainly serum albumin, without a loss of protein or binding activity.

Chromatography, Affinity↗
PubMed1987

An enzyme-linked immunosorbent assay (ELISA) for human sex hormone-binding globulin.

An enzyme-linked immunosorbent assay (ELISA) of the "sandwich-type" for sex hormone binding globulin (SHBG) has been developed. A rabbit anti-SHBG antibody (RAb) is immobilized to the microtitre plate. After incubation with standards and samples a second monospecific rabbit anti-SHBG antibody, labelled with alkaline phosphatase is added (RAb). Following further washing substrate is added, colour developed and the plate read at 405 nm wavelength on a standard ELISA plate reader. The assay is not influenced by the presence of steroids at the binding site, and shows good agreement to SHBG binding capacity assay and commercially available IRMA. Its sensitivity, specificity and precision allows its use in the routine laboratory. The SHBG ELISA has been used to measure SHBG concentrations in sera of normal men, women, pregnant women, and women receiving high-dose medroxyprogesterone acetate as a treatment of metastatic breast cancer.

Enzyme-Linked Immunosorbent Assay↗
PubMed1987

Radioimmunoassay of 5-hydroxy-3-indole acetic acid.

A direct radioimmunoassay of the methyl ester of urinary and serum 5-hydroxy-3-indole acetic acid is described. The antiserum, raised in a rabbit against a conjugate of bovine serum albumin with 5-hydroxytryptamine hemisuccinamide, contained two antigenic fractions, one binding N-acyl 5-hydroxytryptamine, and the other binding methyl ester of 5-hydroxy-3-indole acetic acid, and N-acyl 5-hydroxytryptamine. The N-acyl 5-hydroxytryptamine binding fraction was removed by affinity chromatography on a N-acyl 5-hydroxytryptamine agarose gel in the presence of excess methyl ester of 5-hydroxy-3-indole acetic acid. The antibody methyl ester of 5-hydroxy-3-indole acetic acid complexes were dissociated and this affinity-purified antiserum was used in all experiments. Polyethylene glycol in combination with goat anti-rabbit IgG was used to separate bound and unbound 125I-labeled Bolton-Hunter reagent- 5-hydroxytryptamine conjugate. Sample preparation (esterification of 5-hydroxy-3-indole acetic acid to its methyl ester) was performed with trimethylsilyldiazomethane in dioxane. In the analysis of urine, the reagents used in the methylation served as diluents, contributing to the final dilution of 1:1100. In the analysis of serum, a deproteination step (ethanol precipitation) prior to methylation was necessary to obtain reproducible results. The methylated 5-hydroxy-3-indole acetic acid was then extracted with ethyl acetate and the extract redissolved in assay buffer. The minimal detectable concentration of methyl ester of 5-hydroxy-3-indole acetic acid was 1.1 mumol/l (0.21 mg/l 5-hydroxy-3-indole acetic acid) urine or 100 fmol/tube.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Specificity↗
PubMed1987

(Z)-17 beta-hydroxy-17 alpha-(2-[125I]iodovinyl)-4-estren-3-one: a new specific gamma-emitting ligand for determination of progesterone receptor.

An iodine-125 labeled ligand for progesterone receptor determination was synthesized: (Z)-17 beta-hydroxy-17 alpha-(2-[125I]iodovinyl)-4-estren-3-one ([125I]SH-D 510). The ligand is stable chemically as well as under the conditions of a receptor assay. The relative binding affinity of the nonradioactive compound towards human uterine progesterone receptor was 7.0 for the Z-isomer (promegestone (R5020) 1.0) and 0.95 for the E-isomer. 4 S and 8 S receptor forms were obtained on sucrose density gradient analysis. Progesterone receptors were assayed in 103 human mammary tumour cytosols, using either [3H]promegestone or [125I]SH-D 510. The coefficient of correlation was r = 0.951.

Animals↗