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Biomedical subjects

R Hampl

Publications and source records attributed to R Hampl.

At least 55 records · Page 3Linked to original sources
PubMed1998

Identification of isoflavonoids in beer.

The isoflavonoids, genistein (4',5,7-trihydroxyisoflavone), biochanin A (5,7-dihydroxy-4'-methoxyisoflavone), daidzein (4',7-dihydroxyisoflavone), and formononetin (7-hydroxy-4'-methoxyisoflavone) are supposed to be health-promoting dietary factors of plant origin. They are particularly abundant in seeds and other parts of many plant species belonging to Leguminosae. The most popular source of isoflavonoids in human diet is soy. Here, evidence is presented that isoflavonoids are regularly found in beer. Diethyl ether extracts of beer were fractionated on thin-layer chromatography-silica, (straight phase) and rechromatographed using a reversed phase high-performance liquid chromatography octadecylsilica column. The fractions were analyzed by two recently developed radioimmunoassays, the first of them being specific for diadzein/formononetin and the second one specific for genistein/biochanin A. The immunoreactivity was found only in fractions with the mobility corresponding to the positions of standards on control chromatograms. Additionally, 26 samples of bottled beer were analyzed for isoflavonoid content using the combination of reversed phase high-performance liquid chromatography and radioimmunoassay. The sum of the four isoflavonoids ranged from 1.26 to 29 nmol/L in individual beers. Formononetin was the major isoflavonoid (0.19-14.99 nmol/L), whereas the concentration of daidzein was several times lower (0.08-2.5 nmol/L). Genistein and biochanin A concentrations were comparable, ranging from 0.169-6.74 nmol/L and from 0.820-4.84 nmol/L for genistein and biochanin A, respectively. It is concluded that beer contains significant amounts of biologically active isoflavonoid phytoestrogens.

Beer↗
PubMed1998

Radioimmunoassay of free genistein in human serum.

Two radioimmunoassay (RIA) systems for genistein have been established, based on polyclonal antibodies against genistein-4'-O-(carboxymethyl)ether-bovine serum albumin and genistein-7-O-(carboxymethyl)ether-bovine serum albumin conjugates. The sensitivities of assays were 4.44 and 10.4 fmol (1.2 and 2.8 pg)/tube, respectively, the intraassay coefficients of variation ranged from 3.54 to 9.30%, the interassay C.V. varied from 6.72 to 19.7%, depending on the type of method and on genistein concentration. The cross-reactivities with other chemically related compounds (with exception of genistein derivatives at the position used for construction of the immunogen) were 5.5 and 6.1% for daidzein and 3.9 and 0.04% for formononetin in RIAs using reagents prepared through positions 4'- and 7- of genistein, respectively. The method was used for measurement of genistein levels in 26 omnivore subjects and in three volunteers after consumption of a meal prepared from 125 g of cooked whole soybeans. The values obtained in ether extracts from human sera were almost identical for both RIA systems, indicating that both RIAs measure the same entity.

Cross Reactions↗
PubMed1998

Immunoassay of 7-hydroxysteroids: 1. Radioimmunoassay of 7beta-hydroxy dehydroepiandrosterone.

High sensitivity radioimmunoassay of 3beta,7beta-dihydroxy-5-androsten-17-one (7beta-OH-DHEA) has been developed and evaluated. The method is based on polyclonal rabbit antisera raised against its 19-O-(carboxymethyl)oxime bovine serum albumin conjugate and bridge- and position homologous [125I]iodotyrosine methyl ester as a tracer. Alternatively, [3H]tracer has been prepared, which was recognized by the antiserum as well, but the assay sensitivity was lower. The identity of measured immunoreactive material was confirmed by high performance liquid chromatography which separated 7beta-OH-DHEA from its 7alpha-isomer. Using radioiodinated tracer, the sensitivity of the method was 3.48 fmol (1.06 pg) per tube, the mean recovery of standard added to steroid-free serum was 98.5%. Free (unconjugated and not-esterified) 7beta-OH-DHEA amounted in average 5.8% of the total 7beta-OH-DHEA present in human serum. It was measured in 42 normal subjects (28 females and 14 males) and in 92 randomly selected patients with various endocrinopathies. The mean values +/- SD in normals were 2.05 +/- 1.02 nmol l(-1), the broad range of values from undetectable levels to 10.3 nmol l(-1) was found in the patients. Serum levels of free 7beta-OH-DHEA in the patients significantly correlated with DHEA and its sulfate.

Androsterone↗
PubMed1998

Allopregnanolone in women with premenstrual syndrome.

5Alpha-reduced metabolites of progesterone, especially 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone) are now listed to neurosteroids. Their anesthetic properties can be explained by their allosteric interaction with GABA(A) receptors. A woman's organism is provided with an abundance of progesterone during the luteal phase of the menstrual cycle and its level falls down sharply with the first day of menses. The level of allopregnanolone follows that of progesterone. Many women suffer from so called premenstrual syndrome (PMS) during the luteal phase. In this study we have determined allopregnanolone and progesterone levels and their ratios in order to assess the over-all activity of C21-steroid 5alpha-reductase in these patients and in controls. Significantly lower levels of both progesterone and allopregnanolone than in controls have been found in PMS patients in the follicular phase only.

Adult↗
PubMed1998

Serum Levels of Neurosteroid Allopregnanolone in Patients with Premenstrual Syndrome and Patients after Thyroidectomy.

OBJECTIVE: To evaluate whether altered levels of progesterone and its main neuroactive metabolite allopregnanolone do occur in premenopausal women. The second part of this study deals with allopregnanolone levels in thyreoidectomized women. METHODS: Allopregnanolone, a neurosteroid acting by its allosteric interaction with GABAA receptors and progesterone, were determined in two groups of patients which have in common certain psychic disorders generally characterized by the depression and anxiety, namely in 23 women with premenstrual syndrome (PMS) and in 52 women after total thyreoidectomy. The control groups consisted of women of the same age without premenstrual complaints and with normal thyroid function, respectively. RESULTS: Significantly lower values of allopregnanolone in PMS patients than in controls have been found in the follicular phase, indicating the lower peripheral activity of 5alpha-reductase of C21-steroids detectable at low progesterone levels only. In the thyroidectomized patients significantly higher values of allopregnanolone have been found in the luteal phase. CONCLUSION: The increase of allopregnanolone level in thyroidectomized patients may represent one of the counterregulatory mechanisms protecting the organism from some consequences of hormonal disbalance after thyroid ablation.

Journal Article↗
PubMed1997

Evaluation and separation of steroid-bovine serum albumin conjugates by high-performance liquid chromatography.

The conventional methods for characterization of steroid immunogens are based on the determination of the total amount of hapten bound to the protein carrier either by the UV spectroscopy or titration of unsubstituted amino groups. These methods do not allow more detailed insight into the immunogen composition. HPLC of the immunogen combined with UV detection is a relatively rapid and convenient method enabling determination of the hapten content in each fraction and, eventually, separation of individual fractions differing in the hapten content or purification of crude product.

Acetonitriles↗
PubMed1997

A novel radioimmunoassay for daidzein.

A radioimmunoassay for daidzein was established, based on polyclonal antibodies against daidzein-4'-O-(carboxymethyl)ether-BSA. The sensitivity of the assay was 0.4 pg/tube; the intra- and interassay coefficients of variation varied from 4.1 to 11.5% and from 5.6 to 21.7%, respectively, depending upon the method (direct or extraction) and concentration of daidzein in the sample. The cross reactivities with other chemically related compounds, with the exception of 4'-derivatives of daidzein, were 2.4% for dihydrodaidzein, 1.3% for genistein, 1.5% for biochanin A, and 1.6% for equol, respectively. The method was used for measurement of daidzein levels in 105 normal human subjects and in three volunteers after consumption of a meal prepared from 125 g of cooked whole soybeans. The daidzein values obtained following diethyl ether extraction of human sera was only 8% of that obtained by direct radioimmunoassay. We suggest that this difference is caused by cross-reacting daidzein 4'-glucuronides and -sulfates present in serum. Using ether extraction, the basal serum levels of free daidzein were 0.11 ng/mL (0.43 nmol/L), with 14 subjects showing no detectable levels. Levels were detectable in all subjects with the direct assay with a mean value of 7.1 ng/mL (28.0 nmol/L). Peak levels were reached 4 hours after ingestion of the soybeans. The levels were 10.3 +/- 3.6 ng/mL (40.4 +/- 14.3 nmol/L) for free daidzein and 129.4 +/- 36.1 ng/mL (509 +/- 142 nmol/L) for total immunoreactive compounds. After 24 hours, the levels were still clearly distinguishable from the basal levels; the concentrations were 0.43 +/- 0.15 ng/mL (1.69 +/- 0.59 nmol/L) and 24.36 +/- 6.07 ng/mL (95.9 +/- 23.9) for free and total immunoreactive material, respectively. It is concluded that this is the first immunoassay for a phytoestrogen in human biological fluids, and for the first time serial assays of unconjugated daidzein in plasma have been possible.

Animals↗
PubMed1997

Inhibition of rat renal and testicular 11 beta-hydroxysteroid dehydrogenase by some antihypertensive drugs, diuretics, and epitestosterone.

With regard to previous finding of an inhibitory activity of furosemide on 11 beta-hydroxysteroid dehydrogenase, 16 other commonly used diuretics have been tested as to their ability to inhibit rat renal, and in four instances also testicular 11 beta-hydroxysteroid dehydrogenase, using glycerrhetinic acid as a standard. In addition, epitestosterone has been tested as well, with respect to its recently demonstrated inhibitory activity on several other enzymes of androgen biosynthesis. Besides corticosterone, 11 beta-hydroxy-4-androstene-3,17-dione has been used as a substrate. Of all drugs studied, quinapril, dihydralazin, trandolapril, metipamid, methyldopa, betaxolol only appeared to be weak inhibitors of 11 beta-hydroxysteroid dehydrogenase, with an inhibitory activity 10-28% of that of glycyrrhetinic acid. Using corticosterone as a substrate, epitestosterone displayed a weak inhibitory activity with Ki 850, 1200 nmol/l and Vmax 2420, 3900 nmol/l.min for renal and testicular enzyme, respectively. In contrast to kidneys, the testicular 11 beta-hydroxysteroid dehydrogenase accepted also 11 beta-hydroxy-4-androstene-3,17-dione as a substrate, which could be inhibited by epitestosterone (Ki 1490 nmol/l, Vmax 1150 nmol/l.min). The results represent further evidence for different substrate specificity of renal and testicular 11 beta-hydroxysteroid dehydrogenase.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

Epitestosterone in human blood and prostatic tissue.

Epitestosterone, a C19-steroid with anti-androgenic activity, was determined in the plasma of 234 boys and men from the ages of 6-86 years, and in the prostate tissue of 15 men 55-82 years of age. It was documented that, while in adulthood the concentration of epitestosterone is about ten times lower than the concentration of testosterone, in the pre-pubertal period the level of epitestosterone is similar or even higher than that of testosterone. In the hyperplastic prostate tissue the content of epitestosterone is comparable to that of androstenedione, it is about twice as high as the content of testosterone and approximately half that of the content of dihydrotestosterone. At least in the case of pre-pubertal boys and in the prostatic tissue it is therefore possible to include epitestosterone into consideration as a regulatory factor for the androgen-dependent events.

Adolescent↗
PubMed1997

Age and sex related differences in serum levels of unconjugated dehydroepiandrosterone and its sulphate in normal subjects.

Dehydroepiandrosterone sulphate (DHEAS) and unconjugated dehydroepiandrosterone (DHEA) have been determined in the blood serum of normal subjects of both sexes from 1 month to 100 years of age. In total, 92 girls, 49 boys, 211 women and 110 men were investigated. The effects of age and sex on the levels of the hormones were measured. DHEAS levels declined rapidly during the first year of life and were maintained at a minimum level for 5 years. They increased significantly from 6 to 7 years of age and reached maximum levels in women at about 24 years and in men at about 30 years of age. They then declined rapidly in both sexes but the fall which occurred after 50 and 60 years of age respectively was only moderate. Age-related unconjugated DHEA levels were different. After the first month of life DHEA levels were relatively high and declined more slowly. The minimum level was observed in girls between 5 and 7 years and in boys between 5 and 9 years of age. A significant rise then began and levels reached a maximum in women as well as in men at about 20 years of age. In men levels then declined up to the age of 80. In women the DHEA levels declined during the next 15 years and from approximately 36 years of age they again rose significantly up to a second peak. A mild but significant decline then resumed. There was a difference in the levels of DHEA and DHEAS depending on sex. Unlike DHEAS, unconjugated DHEA was higher in women than in men. However, this difference was significant only in some age groups: during puberty (between 11 and 15 years of age), in the premenopausal period (between 36 and 45 years of age) and in the older group (after 60 years of age). Age- and sex-related dependencies were different between DHEAS and DHEA. They indicate the possible variable secretion and dynamics of their (inter)conversion. We have concluded that DHEA measurements cannot be a substitute for DHEAS and vice versa.

Adolescent↗
PubMed1997

MINIREVIEW 7-HYDROXYLATED DERIVATIVES OF DEHYDROEPIANDROSTERONE: WHAT ARE THEY GOOD FOR?

In the late fifties and early sixties our group has found that 3beta,7alpha-dihydroxy-5-androsten-17-one (7alpha-hydroxy-dehydroepiandrosterone) is a natural constituent of human body fluids. Later, the enzyme activity responsible for its formation has been demonstrated in many animal and human tissues including the foetal ones. The physiological role of this and related steroids has not been understood well for decades. As late as in 1994 Morfin and his group have shown that 7alpha-hydroxy-dehydroepiandrosterone may be a locally active metabolite, responsible for recently discovered immunostimulatory or immunomodulatory effects of dehydroepiandrosterone.

Journal Article↗
PubMed1996

Concentration of the endogenous antiandrogen epitestosterone and androgenic C19-steroids in hyperplastic prostatic tissue.

Epitestosterone (epiT, 17 alpha-hydroxy-4-androsten-3-one), an endogenous C19-steroid in humans, was considered for a long time as a physiologically inactive steroid. Recently, its antiandrogenic properties have been discovered. For the evaluation of its biological availability in the target organs the tissue concentration is of importance. EpiT, testosterone, dihydrotestosterone, and androstenedione concentrations in prostatic tissue were determined in 15 prostate samples obtained by suprapubic prostatectomy for benign prostatic hyperplasia. The steroids were extracted and separated by high-pressure liquid chromatography and determined by specific radioimmunoassay (RIA) methods. The concentration of epiT (mean 58.4 +/- 40.4 SD, range 14.0-144.0 fmol/mg protein) exceeded that of testosterone and was approximately as high as that of dihydrotestosterone. EpiT level increased with age and the correlation was significant (P < 0.05). It did not correlate significantly with testosterone but did with androstenedione and dihydrotestosterone (P < 0.05, each). As expected, a positive correlation was found between testosterone and dihydrotestosterone levels.

Aged↗
PubMed1996

The concentrations of the endogenous C19-steroids in hyperplastic prostatic tissue and the effect of finasteride treatment.

The concentrations of the antiandrogenic endogenous steroid epitestosterone (epiT) and of testosterone, dihydrotestosterone (DHT) and androstenedione in the prostate were determined in tissue samples obtained from 21 patients who underwent suprapubic prostatectomy for benign prostatic hyperplasia. Fifteen patients received no hormonal treatment before surgery and the other 6 patients were pretreated for 8 weeks before surgery with an oral dose of 5 mg/day finasteride. The steroids were extracted and separated by high pressure liquid chromatography and determined by specific radioimmunoassays. The concentration of epiT (mean 58.4 +/- 40.4 S.D., range 14.0-144.0 fmol/mg protein) exceeded that of testosterone and was nearly as high as that of DHT. The prostatic tissue from the patients treated with finasteride for 8 weeks showed a significant decrease not only in DHT but also in androstenedione and epiT, whereas the concentration of testosterone increased significantly.

5-alpha Reductase Inhibitors↗
PubMed1996

Sex hormone-binding globulin in endocrine regulation. (Minireview).

Evidence has been accumulated that sex hormone-binding globulin (SHBG) does not act only as a regulator of bioavailability of sex steroids, but represents an important factor in various endocrine regulatory systems. As documented by both clinical and in vitro studies, SHBG biosynthesis in the liver and also in other tissues is under the control of various hormones and other regulatory factors as estrogens, thyroid hormones, insulin, growth hormone and insulin-like growth factor-I (IGF-I). In addition to its effect on transport and uptake of sex hormones by their target cells, SHBG may act as a true hormone through its membrane receptors of the latter targets. The recent data on the over-all role of SHBG in endocrine regulations are critically reviewed here.

Journal Article↗
PubMed1996

Antirenotropic action of antiandrogens cyproterone acetate, casodex, flutamide and epitestosterone.

The antirenotropic activities of three antiandrogens which are frequently used in the clinical praxis (cyproterone acetate, flutamide and casodex) and of natural endogenous antiandrogen epitestosterone were compared. The substances were administered in oil intraperitoneally to intact male mice. The weight of kidneys was decreased most effectively by casodex and epitestosterone, though the antiandrogenic activity expressed by the decreased weight of seminal vesicles was confirmed in all preparation tested, except for flutamide. Only epitestosterone significantly reduced the level of plasma testosterone, whereas casodex increased testosterone level in plasma. LH level was decreased by testosterone propionate and epitestosterone significantly, but about 50 percent increase in the mean LH level in casodex treated animals did not reach the statistical significance.

Journal Article↗
PubMed1996

[Epitestosterone as an endogenous antiandrogen in men].

The authors assessed in the plasma of 156 boys and men aged 6 - 65 years and in prostatic tissues of 15 men aged 55 - 82 years epitestosterone, C19-steroid with anti-androgenic properties. It was revealed that during the prepubertal period the epitestosterone level is higher than that of testosterone, in adult age the epitestosterone is about ten times lower than the testosterone concentration. In tissue of hyperplastic prostates the epitestosterone level is comparable with the androstendione level; it is about twice as high as the testosterone level and approximately half as high as the dihydrotestosterone level. Thus at least during the prepubertal period in boys and in the androgen-dependent prostate tissue a more significant participation of epitestosterone in the regulation of androgen-dependent processes must be taken into consideration.

Adolescent↗
PubMed1995

A decreasing CD4+/CD8+ ratio after one month of treatment with stanazolol in postmenopausal women.

Androgens influence some immunological processes, including the differentiation of T-cells in CD4+ (helpers) or CD8+ (suppressors/cytotoxic) phenotype. In nine postmenopausal osteoporotic women the effect of stanazolol on lymphocyte counts, CD3+ and the immunoregulatory index (CD4+/CD8+) were investigated. In the placebo group, ten postmenopausal osteoporotic women of similar age were included. The means of the investigated indices after stanazolol as compared with the values before treatment were as follows: lymphocyte counts (cells/microL +/- SEM) 2974 +/- 225 versus 2313 +/- 166, CD3+ (%) 54.3 +/- 5.5 versus 70.9 +/- 1.6 (P < 0.05); CD4+/CD8+ ratio 1.8 +/- 0.02 versus 2.5 +/- 0.28 (P < 0.05). The values after placebo as compared with the values before placebo were: 2558 +/- 201 versus 2370 +/- 256, 62.9 +/- 2.1 versus 64.8 +/- 1.7 and 1.6 +/- 0.2 versus 1.6 +/- 0.1 in sequence. The treatment was controlled by the serum stanazolol levels before and after steroid administration (unmeasurable versus 20.8 +/- 3.4 nmol/L, P < 0.01). The good compliance of the therapy was confirmed by a decline of serum LH (U/L; 30.1 +/- 3.1 versus 24.7 +/- 2.8, P = 0.014), FSH (U/L; 108.9 +/- 13.1 versus 93.3 +/- 12.8, P = 0.012) and serum sex hormone binding globulin (SHBG; nmol/L; 53.3 +/- 13.3 versus 11.2 +/- 1.9, P < 0.01). The decline of SHBG indicates a good tissue sensitivity to the androgen. There were no significant differences between hormonal parameters before and after placebo treatment. In conclusion, the immunosuppressive effect of the androgen, stanazolol, was confirmed in the investigated postmenopausal osteoporotic women.(ABSTRACT TRUNCATED AT 250 WORDS)

Anabolic Agents↗