Usefulness of the Calgary Syncope Symptom Score for the diagnosis of vasovagal syncope in the elderly.

AIMS: The Calgary Syncope Symptom Score (CSSS) has been validated as a simple point score of historical features with high sensitivity and specificity for the diagnosis of vasovagal syncope (VVS) in younger populations without evidence of structural heart disease. Our purpose was to evaluate the performance of the CSSS in an elderly population with suspected VVS. METHODS AND RESULTS: Hundred and eighty patients of ≥60 years of age (mean 73.4 ± 7.8) with suspected clinical diagnosis of VVS were studied. The CSSS (VVS score ≥-2) was calculated in all patients prior to undergoing head-up tilt test (HUT). A standardized HUT protocol with active nitroglycerin phase was used to reproduce syncopal symptoms as gold standard for diagnosis of VVS. Hundred and forty patients had positive HUT response. Eighty-three patients (42.3%) had CSSS ≥-2 suggesting a diagnosis of VVS. The Calgary Syncope Symptom Score sensitivity was 0.51 [95% confidence interval (CI) 0.42-0.59] and specificity 0.73 (95% CI 0.52-0.85) with positive predictive value and negative predictive value of 0.87 (95% CI 0.77-0.93) and 0.30 (95% CI 0.21-0.40), respectively. One hundred (55.6%) patients had previous history of mild cardiovascular disease documented during assessment prior to HUT. In this population sensitivity and specificity was markedly reduced: 0.13 (95% CI 0.05-0.29) and 0.70 (95% CI 0.57-0.80), respectively. CONCLUSION: The CSSS has a lower sensitivity and specificity in an elderly population presenting with syncope compared to previously validated data in young adults, particularly in elderly patients with previous history of mild cardiovascular disease. A modified CSSS may be needed to improve specificity and sensitivity in this population.

Pulsed-resource dynamics increase the asymmetry of antagonistic coevolution between a predatory protist and a prey bacterium.

Temporal resource fluctuations could affect the strength of antagonistic coevolution through population dynamics and costs of adaptation. We studied this by coevolving the prey bacterium Serratia marcescens with the predatory protozoa Tetrahymena thermophila in constant and pulsed-resource environments for approximately 1300 prey generations. Consistent with arms race theory, the prey evolved to be more defended, whereas the predator evolved to be more efficient in consuming the bacteria. Coevolutionary adaptations were costly in terms of reduced prey growth in resource-limited conditions and less efficient predator growth on nonliving resource medium. However, no differences in mean coevolutionary changes or adaptive costs were observed between environments, even though resource pulses increased fluctuations and mean densities of coevolving predator populations. Interestingly, a surface-associated prey defence mechanism (bacterial biofilm), to which predators were probably unable to counter-adapt, evolved to be stronger in pulsed-resource environment. These results suggest that temporal resource fluctuations can increase the asymmetry of antagonistic coevolution by imposing stronger selection on one of the interacting species.

Regulation of cytosol and nuclear progesterone receptors in rabbit uterus by estrogen, antiestrogen and progesterone administration.

A synthetic progestin, 16 alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3,20-dione (ORG 2058), was utilized to measure progesterone receptors from the rabbit uterus. This steroid has a high affinity for both cytosol and nuclear receptors, with KD values of 1.2 nM (at 0--4 degrees C) and 2.3 nM (at 15 degrees C), respectively. Administration of estradiol-17 beta or a non-steroidal antiestrogen, tamoxifen, for 5 days to estrous rabbits led to a progressive rise in the cytosol receptor levels: from 34,000 to 120,000 (estradiol-17 beta) and 80,000 (tamoxifen) receptors/cell, without any major influence on the nuclear receptor content. A single intravenous injection of progesterone (5 mg/kg) elicited a 3-fold increase in the mean nuclear receptor content at 30 min after injection (from 18,000 to 48,000 receptors/nucleus). Nuclear receptor accumulation was short-lived and returned to control levels within 4 h after treatment. A second dose of progesterone given 24 h later doubled the nuclear receptor level (from 18,000 to 35,000 receptors/nucleus). The concomitant decline in the cytosol receptor content was twice that accounted for by the nuclear receptor accumulation (70,000 vs. 30,000, and 40,000 vs. 17,000 receptors/cell, after the first and second progesterone injection, respectively). Following progesterone administration, the cytosol receptor level reached a nadir by 30 min, exhibited minimal replenishment within the ensuing 24 h, and remained at approx. 50% of the pretreatment values. After a single dose or two consecutive doses of progesterone, total uterine progesterone receptor content declined to about 60% of the level prior to each dose, a nadir being reached at 2 h after treatment.

Interferon-gamma inhibits steroidogenesis and accumulation of mRNA of the steroidogenic enzymes P450scc and P450c17 in cultured porcine Leydig cells.

The inhibitory effects of recombinant porcine interferon-gamma (IFN gamma) on human CG (hCG)-stimulated testosterone production, and on mRNA concentrations of cholesterol side-chain cleavage (P450scc) and 17 alpha-hydroxylase/C17-20lyase (P450c 17) were investigated using porcine primary Leydig cell culture as a model. After preincubation of Leydig cells for 24 h with 1000 pM IFN gamma, hCG-stimulated (10 ng/ml, 2 h) testosterone production was inhibited by 50%, whereas no significant changes were seen in hCG-stimulated cAMP production. Incubation with 10 microM 5-cholestene-3 beta,22(R)-diol or 10 microM 5-cholestene-3 beta,20 alpha-diol together with hCG (10 ng/ml, 2 h) reversed most of the inhibitory effect of IFN gamma, suggesting that IFN gamma inhibits P450scc activity, possibly by inhibiting the substrate (cholesterol) availability for P450scc. Incubation with IFN gamma also decreased basal concentrations of P450scc (45%) and P450c 17 (35%) mRNA, although these changes probably did not contribute to the decreased testosterone production. Long-term treatment with hCG (100 ng/ml, 24 h) increased P450scc mRNA (3- to 4-fold) and P450c 17 mRNA (4- to 5-fold) concentrations. Simultaneous treatment with IFN gamma attenuated these hCG-induced increases in P450scc mRNA (50%) and P450c 17 mRNA (40-100%) concentrations, as well as in testosterone production (77%). This inhibition of testosterone production could only be partly reversed by the hydroxylated cholesterol derivatives. This suggests that in addition to possible suppression of cholesterol availability, decreased P450scc and/or P450c 17 activities (through decreased mRNA concentrations) were also involved in the IFN gamma suppressed steroidogenic capacity of porcine Leydig cells during long-term hCG stimulation.

Regulation of 17 beta-hydroxysteroid dehydrogenase type 1 by epidermal growth factor and transforming growth factor-alpha in choriocarcinoma cells.

17 beta-Hydroxysteroid dehydrogenase type 1 (17HSD type 1) is a steroidogenic enzyme that catalyzes the reversible interconversion of estrone and estradiol. In this study, we investigated the roles of epidermal growth factor (EGF) and tumor growth factor-alpha (TGF alpha) in the regulation of 17HSD type 1 gene expression and catalytic activity in cultured JAR, JEG-3, and BeWo choriocarcinoma cells. EGF and TGF alpha increased 17HSD type 1 protein concentrations in JAR and JEG-3 cells, as measured by time-resolved immunofluorometric assay, and 17HSD catalytic activity, as determined by production of estradiol from estrone. These increases were accompanied by parallel increases in concentrations of the 1.3-kilobase messenger RNA coding for 17HSD type 1 in these cells. EGF receptor tyrosine kinase activity inhibitors, tyrphostins, inhibited EGF action in JEG-3 cells, indicating that tyrosine kinase activity is needed for stimulation of the 17HSD type 1 gene. Treatment with 8-bromo-cAMP or phorbol 12-myristate 13-acetate increased the amount of 17HSD type 1 protein. Furthermore, phorbol 12-myristate 13-acetate potentiated the stimulatory effect of EGF. These results suggest that EGF and/or TGF alpha may play an important role in 17HSD type 1 regulation and, consequently, in estrogen production in the human placenta.

Rat 17 beta-hydroxysteroid dehydrogenase type 1: primary structure and regulation of enzyme expression in rat ovary by diethylstilbestrol and gonadotropins in vivo.

17 beta-Hydroxysteroid dehydrogenase (17HSD) catalyzes the reversible conversion of estrone into estradiol. The complementary DNA (cDNA) coding for rat 17HSD type 1 was cloned from a commercial rat ovarian cDNA library, using human 17HSD type 1 cDNA as a probe. The nucleotide sequence extends for 1160 basepairs (bp), including 1035 bp of open reading frame, a stop codon, and 125 bp of 3'-untranslated sequence. The cDNA encodes a protein of 344 amino acids, with a calculated molecular mass of 36,967 daltons. The overall amino acid identity and similarity between rat and human 17HSD type 1 enzymes are 68% and 80%, respectively. Immunohistochemistry and in situ and Northern hybridizations were used to study regulation of the enzyme in rat ovary in vivo. Enzyme expression was detected in granulosa cells only, whereas no expression was observed in stromal or thecal cells. The enzyme was almost undetectable in ovaries from immature hypophysectomized rats. After 2-day treatment with recombinant FSH (recFSH), an induction of 17HSD type 1 expression was observed in granulosa cells of growing antral follicles. During 5 days of diethylstilbestrol (DES) treatment, a time-dependent increase in developing follicles was observed, showing strong expression of 17HSD type 1 in granulosa cells. Treatment with recFSH for 2 days in DES-primed animals resulted in down-regulation of ovarian enzyme expression. This reduction of enzyme expression was associated with luteinization of the follicles. hCG treatment of recFSH- or DES- plus recFSH-primed animals further induced luteinization, resulting in strong down-regulation of 17HSD type 1 expression. The enzyme was not detected in corpora lutea. The data show that 17HSD type 1 expression in rat ovary is regulated by gonadotropins and estrogens. The results suggest that expression of 17HSD type 1 and that of cytochrome P450 aromatase are regulated by distinct mechanisms, and 17HSD type 1 may be down-regulated earlier than P450 aromatase during luteinization, limiting estradiol biosynthesis in luteinizing granulosa cells in rat ovary.

Spatial and temporal distribution of corticosteroid-binding globulin and its messenger ribonucleic acid in embryonic and fetal mice.

Glucocorticoids influence fetal development, and their actions are regulated by plasma corticosteroid-binding globulin (CBG). Immunohistochemistry and in situ hybridization were, therefore, used to localize CBG and its mRNA in sections of embryonic and fetal mice and their associated placental tissues from day 5 of gestation until term (day 19). In the fetus, CBG mRNA was first detectable in the hepatocytes on day 11 of gestation. The amount of CBG mRNA in these cells increased transiently to a maximum on days 15-16 of gestation and was negligible by day 19. In hepatocytes, CBG immunoreactivity correlated with the distribution and relative abundance of CBG mRNA. The fetal exocrine pancreas also contained CBG mRNA, but this was only present on days 15-16 of gestation, while immunoreactive CBG persisted in these cells until term. Immunoreactive CBG was detected in the tubular cells of the developing fetal kidney as early as day 13, but CBG mRNA was never found in the fetal kidney, suggesting that the protein is probably sequestered from fetal blood directly or via the glomerular filtrate. The placenta contained immunoreactive CBG throughout gestation, even before its detection in fetal tissues, and it was most abundant in the spongiotrophoblasts and the extracellular matrix surrounding fetal and maternal capillaries. However, CBG mRNA was not detected in the placenta at any gestational age. Therefore, CBG present in the placenta is most likely of maternal origin and may influence the activities of steroid hormones that control placental development and/or function. The presence of smaller immunoreactive polypeptides in placental extracts, compared to CBG in corresponding maternal serum samples, suggests that this process may involve an interaction between maternal CBG and placental proteinases. The results presented here suggest that temporal and spatial changes in the localization of CBG and its mRNA in the fetus may influence the effects of steroid hormones on developing tissues.

Effects of metoclopramide-induced hyperprolactinemia during early follicular development on human ovarian function.

Nine healthy women, aged 25 to 36 yr, were treated with metoclopramide (MC) (10 mg orally three times daily) from the first to the sixth day of their cycle (treatment A) for two successive cycles (n = 18) and six of these women later received MC from -3 to the fifth day of the menstrual cycle (treatment B) during one or two cycles (n = 10), to investigate the effects of hyperprolactinemia during the early phase of ovarian follicular growth. Comparisons were performed with control cycles in the same women. The treatment cycles were characterized by low serum concentrations of LH during the early follicular phase and at midcycle, low early follicular phase serum testosterone (T) levels and high luteal phase T and free T index values, with no significant differences between A and B treatment modalities. We classified the treatment cycles into two categories, seriously disturbed and normal or only slightly disturbed, on the basis of ultrasonographic findings and midcycle estradiol (E2) and luteal phase progesterone (P) concentrations. Folliculogenesis was seriously disturbed in 11 of the 28 treatment cycles (39%). During these cycles, midcycle serum LH and the LH to FSH ratio were lowered, luteal phase LH and FSH increased, midcycle E2 and luteal phase P and the P to E2 ratio decreased, luteal phase T and the free T index and androstenedione increased, and luteal phase 5 alpha-dihydrotestosterone decreased. During the early follicular phase and at midcycle the ratios of T to E2 and androstenedione to E2 were increased, and at midcycle and during the luteal phase of the cycle the ratio of T to 5 alpha-dihydrotestosterone was increased. These changes in steroid hormones were probably of ovarian origin since the serum concentrations of dehydroepiandrosterone sulfate and sex hormone-binding globulin were similar in seriously disturbed and control cycles. Four of the nine study subjects were hyperprolactinemia sensitive (disturbed folliculogenesis) and five hyperprolactinemia resistant (no disturbance in folliculogenesis). During the control cycles the hyperprolactinemia-sensitive women had significantly higher serum concentrations of T than the other women. The present observations indicate that hyperprolactinemia may impair the development of the ovarian follicles during their recruitment period, especially in women with relatively high serum T levels.

Structure and chromosomal location of the gene encoding mouse corticosteroid-binding globulin: strain differences in coding sequence and steroid-binding activity.

Corticosteroid-binding globulin (CBG) is a member of the serine proteinase inhibitor superfamily and is responsible for the plasma transport of glucocorticoids. The mouse Cbg gene structure has been deduced from two non-overlapping DNA fragments of a lambda EMBL-3 genomic library, as well as PCR amplification of the approx. 2 kb of genomic DNA that lies between them. Mouse Cbg comprises five exons that span a region of approx. 10.5 kb, and has been localized in tight linkage with the Aat (alpha 1-antitrypsin) and Spi (serine proteinase inhibitor) gene complex on chromosome 12, in a region syntenic with this genetic locus on human chromosome 14. Intron-specific oligodeoxyribonucleotide primers were also used to PCR-amplify Cbg coding regions from several mouse strains. No differences were found in the Cbg coding sequences of BALB/c and C57BL/6J-cpk/cpk mice, while two mutations were found within RIIIS/J Cbg that result in Lys201-->Glu and Ala357-->Thr substitutions in the mature mouse CBG polypeptide. To assess what impact these substitutions might have on the steroid-binding activity of RIIIS/J CBG, these mutations were introduced separately or together into a BALB/c mouse Cbg cDNA. Expression of these mutants in the MDCK cell line indicated that the Lys201-->Glu substitution accounts for the abnormal steroid-binding affinity of CBG in RIIIS/J mice.

Characterization of 17 beta-hydroxysteroid dehydrogenase type 1 in choriocarcinoma cells: regulation by basic fibroblast growth factor.

17 beta-Hydroxysteroid dehydrogenase type 1 (17-HSD type 1) is a steroidogenic enzyme catalyzing reversible interconversion of estradiol and estrone. 17-HSD type 1 is actively expressed in human placenta. We characterized 17-HSD type 1 expression and its regulation by basic fibroblast growth factor (bFGF) in JAR, JEG-3 and BeWo choriocarcinoma cell lines. Based on Southern and Northern analysis, as well as measurement of catalytic activity and immunoreactive protein, all the choriocarcinoma cell lines contained and expressed the gene coding for 17-HSD type 1, identical to that of normal human cells. However, the cell lines showed marked quantitative differences in the levels of expression of the enzyme, being lowest in JAR cells and highest in BeWo cells, as measured by immunofluorometric assay, Northern analysis and catalytic activity. These differences in the basal level of expression were most probably not based on any sequence differences in the putative proximal promoter area of the gene in different cell lines, since no dissimilarities were observed in the 806 bp region upstream from the transcription start site of 1.3 kb mRNA coding for 17-HSD type 1 except for frequent polymorphism characteristic of normal human cells using polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis. The reductive (estrone-->estradiol) activity was about 4-7 times higher compared with the oxidative activity (estradiol-->estrone) in all the cell lines studied, indicating that in these choriocarcinoma cell lines, 17-HSD activity favours estradiol formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of steroid and steroid sulfate production and aromatase activity in cultured human granulosa-luteal cells.

The regulation of the production of steroids and steroid sulfates and the activity of aromatase in human luteinized granulosa cells were investigated. The cells were cultured for 48 h in the presence or absence of hCG and FSH. Basal production of pregnenolone (Pre, 0.3 +/- 0.03 ng/micrograms protein) and progesterone (P, 19.3 +/- 1.7 ng/micrograms protein) were high compared with that of other steroids beyond P in the steroidogenic pathway. The concentration of 17 alpha-hydroxyprogesterone (17-OHP) was lower 0.17 +/- 0.06 ng/micrograms and that of other steroids in the 4-ene and 5-ene pathways and steroid sulfates less than 0.05 ng/micrograms. Both hCG and FSH (100 ng/ml) stimulated the production of Pre and P 3- to 5-fold, but only minimal stimulation of other steroids and steroid sulfates was observed. Aromatase activity of granulosa-luteal cells was measured from the rate of formation of 3H2O from 1 beta-[3H]androstenedione (1 beta[3H]A) after exposing the cells to hCG, FSH or estradiol (E2) for 48 h. Basal aromatase activity was relatively low, but hCG and FSH stimulated aromatase 8- and 4-fold, respectively. The incubation of granulosa-luteal cells with E2 did not affect basal aromatase activity, but E2 augmented FSH-stimulated aromatase 1.4-fold (P less than 0.025). The results suggest that there is low 17 alpha-hydroxylase and steroid sulfokinase activity in human granulosa-luteal cells. Aromatase activity in these cells is regulated by both hCG and FSH, and intra-ovarian estrogens may regulate granulosa cell aromatase activity.

Role of ethanol metabolism in the inhibition of testosterone biosynthesis in rats in vivo: importance of gonadotropin stimulation.

The mechanisms by which ethanol (EtOH, 1.5 g/kg) inhibits testicular testosterone synthesis were studied in nonstimulated and human chorionic gonadotropin (hCG, 50 IU/kg)-treated male rats. To dissociate the effects caused by ethanol metabolism, the alcohol dehydrogenase inhibitor 4-methylpyrazole (4MP, 10 mg/kg) was given to half of the rats 30 min before EtOH. The 4MP had little or no effect in the nonstimulated rats on the EtOH-induced decreases in the concentrations of serum testosterone and of the intratesticular steroids of the testosterone biosynthetic pathway measured, but reduced the EtOH-induced elevation in the intratesticular pregnenolone-to-progesterone ratio. In contrast, 4MP pretreatment markedly reversed the EtOH-induced decrease in serum and intratesticular testosterone and increase in intratesticular pregnenolone concentrations in the hCG-stimulated rats. Simultaneously, the EtOH-induced elevations in the intratesticular pregnenolone/progesterone and androstenedione/testosterone ratios were abolished. In the EtOH-treated rats whose EtOH metabolism was blocked by 4MP pretreatment, the intratesticular testosterone concentrations were negatively correlated with the elevated serum corticosterone levels. It is concluded that: (1) EtOH metabolism is involved in the inhibition of testicular steroidogenesis in vivo. This effect is pronounced during gonadotropin-stimulated conditions. Thus, previously reported "discrepancies" between the in vivo and in vitro results are clarified; (2) corticosterone seems also to be involved in the EtOH-induced inhibition of steroidogenesis. This effect is also pronounced during gonadotropin-stimulated conditions; and (3) without external gonadotropin stimulation other inhibitory mechanisms, such as decreased stimulation by luteinizing hormone, are prevalent.

Effect of growth hormone administration on human ovarian function and steroidogenic gene expression in granulosa-luteal cells.

OBJECTIVE: To study the effect of growth hormone (GH) in combination with an ultrashort-term gonadotropin-releasing hormone analogue/human menopausal gonadotropin (hMG)/human chorionic gonadotropin (hCG) regimen in ovarian hyperstimulation for in vitro fertilization (IVF). DESIGN: Prospective randomized placebo-controlled study. SETTING: University-based IVF program. PATIENTS: Fifty-four normally cycling women (27 control and 27 GH-treated) participated in this study. INTERVENTIONS: Human recombinant GH (24 IU)/placebo was given intramuscularly on alternate days starting on cycle day 4 until the day of last hMG injection. RESULTS: Serum estradiol (E2) and progesterone (P) concentrations were slightly lower in the GH group than in the placebo group on the day of hCG injection and 1 day thereafter (P < 0.01 to 0.001). Serum luteinizing hormone, follicle-stimulating hormone, prolactin, testosterone (T), and sex hormone-binding globulin did not differ between the groups. The follicular fluid (FF) concentration of T was higher in the GH group than in the placebo group (15.9 +/- 6.0 nmol/L versus 10.2 +/- 4.9 nmol/L, P < 0.005), and no differences were observed in the FF concentrations of E2, P, and insulin-like growth factor I between the groups. In granulosa cells isolated from patients who received GH treatment, the levels of 3 beta-hydroxysteroid dehydrogenase and aromatase messenger ribonucleic acid were significantly higher than in the patients receiving placebo. The number of hMG ampules needed for follicular development and the number of follicles and oocytes recovered were similar in both groups. CONCLUSIONS: These results indicate that GH administration modifies ovarian steroidogenic response to gonadotropins in IVF patients, suggesting a role for GH in the regulation of human ovarian function.

Prolactin suppression by bromocriptine stimulates aromatization of testosterone to estradiol in women.

The effect of follicular phase bromocriptine therapy on the ovarian endocrine response to clomiphene citrate and gonadotropins was studied in 35 tubal infertility patients in a randomized placebo-controlled trial. During bromocriptine treatment, the serum prolactin (PRL) concentration significantly decreased, and consequently the serum estradiol (E2) concentration was significantly higher than in the controls on cycle day 9, and the ratio of testosterone (T) to E2 was decreased from cycle day 8 through day 10. The luteal phase progesterone concentration and the length of the luteal phase were not affected by bromocriptine therapy. The number and quality of oocytes harvested and the cleavage rates were similar in both groups. The present results, together with our previous observations, demonstrate that PRL participates in the regulation of ovarian steroidogenesis, particularly aromatization of T to E2.

Early changes in nucleoplasmic poly(A) polymerase activity in immature rabbit uterus after estradiol administration.

To study the role of post-transcriptional polyadenylation in the mechanism of estrogen action, we measured free nucleoplasmic poly(A) polymerase activity in intact uterine nuclei of immature rabbits at timed intervals after a single intravenous dose of estradiol (20 microgram/kg body weight). Uterine nuclear poly(A) polymerase activity was altered in a biphasic manner by estradiol treatment with maximal activities occurring at 0.5 h and 12 h of steroid administration, at which time periods they were about 2- and 3-fold higher than pretreatment levels, respectively. The later increase in the enzyme activity was totally abolished by a prior cycloheximide (0.5 mg/kg) administration, whereas the initial activation of poly(A) polymerase seemed to occur via mechanism(s) independent of protein synthesis. It thus appears that changes in uterine nuclear poly(A) polymerase closely resemble those previously reported for the activity of RNA polymerase II after estradiol treatment.

Serum distribution of two contraceptive progestins: 3-ketodesogestrel and gestodene.

A cross-over study of two oral contraceptive formulations, containing 30 micrograms ethinylestradiol in combination with 150 micrograms desogestrel (Marvelon) or 75 micrograms gestodene (Femovan), has been performed to compare the serum distribution and pharmacokinetics of gestodene and the active metabolite of desogestrel, namely 3-ketodesogestrel. Serum concentrations of both sex hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG) were also measured and were increased more than 3-fold and 2-fold, respectively, on day 21 of the treatment cycle, with no statistically significant difference between treatment groups. In addition, 35 days after ingestion of either oral contraceptive had ceased, the serum SHBG and CBG concentrations were similar to the pretreatment values. During treatment cycles, increased serum SHBG levels were associated with a redistribution of 3-ketodesogestrel and gestodene such that the non-protein-bound (NPB) and albumin-bound fractions were reduced in concert with an increase in the relative proportions bound to SHBG. The proportion of gestodene bound to SHBG was consistently higher than that observed for 3-ketodesogestrel, and this undoubtedly reflects the higher affinity of SHBG for gestodene (Kd = 1.2 nM at 37 degrees C) when compared to 3-ketodesogestrel (Kd = 4.7 nM at 37 degrees C). It also probably accounts, in part, for the much higher total serum levels of gestodene (8.58 nmol/L) when compared to 3-ketodesogestrel (2.37 nmol/L) during the treatment cycles. Consequently, the absolute amounts of NPB, non-SHBG-bound, and SHBG-bound gestodene are significantly higher than those measured for 3-ketodesogestrel. It is concluded that ethinylestradiol-induced increases in serum SHBG levels during treatment with Marvelon or Femovan, influenced the distribution and total amount of 3-ketodesogestrel and gestodene in serum, respectively, and that this, combined with the higher affinity of SHBG for gestodene, results in a greater amount of bioavailable gestodene compared to 3-ketodesogestrel, despite the smaller dose of gestodene administered.

Comparison of the inhibitory effects of interferons-alpha and -gamma on testosterone production in porcine Leydig cell culture.

In porcine Leydig cell culture, incubation with natural or recombinant human interferon-alpha (IFN-alpha), or recombinant porcine IFN-gamma preparations were effective in inhibiting basal and human chorionic gonadotropin (hCG)-stimulated testosterone production in a dose-dependent manner. Combined treatment with any of the human IFN-alpha preparations plus recombinant porcine IFN-gamma at the maximal inhibitory dose (1,000 pmoles/liter) further increased the inhibitory effect of any single IFN preparation on hCG-stimulated testosterone production. These results show that in porcine Leydig cells, both human IFN-alpha and porcine IFN-gamma are able to inhibit testosterone production and that the inhibitory action can be enhanced significantly by combined treatment with these types of IFNs. The enhancement of the inhibitory effect by combined treatment is consistent with the known presence of distinct cell membrane receptors for IFN-alpha and IFN-gamma.

Human leukocyte interferon inhibits human chorionic gonadotropin stimulated testosterone production by porcine Leydig cells in culture.

Pretreatment of primary porcine Leydig cell cultures with human leukocyte interferon suppressed the subsequent hCG-stimulated testosterone production in a dose-dependent manner, with an ED50 at 13 IU/ml. The treatment had no effect on hCG-binding to its receptor, and the inhibition of testosterone production was not abolished by 8Br-cAMP addition. The results indicate that the site of interferon action on hCG-stimulated testosterone production in primary cultures of porcine Leydig cells is located distal to cAMP formation.

Evidence for an androgen receptor in porcine Leydig cells.

Cytosol and nuclear androgen receptor concentrations were measured in freshly prepared and cultured Leydig cells of immature pig testis with exchange assays using [3H]methyltrienolone as labelled ligand. Androgen receptors in Leydig cells had high affinity for [3H]methyltrienolone and steroid binding specificity typical of an androgen receptor. The mean receptor concentrations were 76 fmol/mg protein and 210 fmol/mg DNA for cytosol and nuclei, respectively. In sucrose gradients, cytosol androgen receptors sedimented in the 4 S region. The cells maintained androgen receptors under culture conditions. Exposure of cultured cells to [3H]methyltrienolone (10 nmol/l) resulted in accumulation of androgen receptors in the nuclei with maximal uptake by 1 h. We conclude that methyltrienolone binding sites with characteristics of androgen receptors were identified in both cytosol and nuclei of porcine Leydig cells.

Steroid sulfates in testis tissue of prostatic cancer patients treated for six months with the gonadotropin releasing hormone agonist buserelin.

In order to assess the extent of inhibition of testicular steroidogenesis during long-term treatment of prostatic cancer with GnRH agonist, we measured the intratesticular levels of 5 steroid sulfate conjugates in human testis tissue removed from patients after 6 months of intranasal treatment with buserelin. The most pronounced decreases were found in testosterone and pregnenolone sulfates, to 1.6 and 7.1%, respectively, of concentrations measured in testis tissue from primarily orchiectomized prostatic cancer patients. In contrast, clearly smaller decreases were found in three other steroid sulfates measured, those of dehydroepiandrosterone (to 26%), 17-hydroxyprogesterone (to 27%) and 5-androstene-3 beta, 17 beta-diol (to 62%). These results are in keeping with our previous analyses of unconjugated steroids in similar tissue samples, and indicate that testicular steroidogenesis per se is not totally blocked by long-term intranasal treatment with GnRH agonist. Testicular steroid sulfate conjugation may be specifically suppressed since the total concentration of these conjugates decreased more than free steroid levels in our earlier measurements.