Effects of insulin-like growth factor I (IGF-I) on enzymatic activity in human adrenocortical cells. Interactions with ACTH

Cells obtained from 6 adult human adrenals or adrenal fragments were cultured in serum-free synthetic medium (McCoy's) in order to study the isolated effects of IGF-I on steroidogenesis and its interactions with ACTH. After addition of peptide, changes in the activities of steroidogenic enzymes were assessed by measuring certain steroids in the spent medium. These included pregnenolone, 17-hydroxypregnenolone (17-OH-Preg), dehydroepiandrosterone (DHA), 17-hydroxyprogesterone (17-OH-P), androstenedione (AD), 11-deoxycortisol and glucocorticoids (chiefly cortisol and its immediate precursors, 11-deoxycortisol and 17-OH-P) and cortisol itself.

The steroid responses obtained with repeated doses of IGF-I (40 ng/ml ≈ 10⁻⁹ M), added at 0, 48 and 72 h, over 4 days' culture were quite different from those obtained with repeated doses of ACTH (0.25 ng/ml ≈ 10⁻¹⁰ M). All the steroids measured increased with time of culture under the influence of ACTH and, apart from pregnenolone which peaked, tended to reach a plateau. With IGF-I, by contrast, DHA, AD, 11-deoxycortisol and glucocorticoid production increased initially, then decreased progressively, whereas pregnenolone, 17-OH-Preg and 17-OH-P production was either absent or negative.

Cumulative steroid production over 4 days reached similar levels in response to a single dose of IGF-I and/or ACTH, with two major exceptions: pregnenolone dropped significantly with IGF-I [46% ± 6 (SEM) as opposed to 93% ± 11 with ACTH, P < 0.005, N = 5], as did 17-OH-P (48% ± 11 vs 113% ± 8 with ACTH, P < 0.001, N = 6). Increased formation of down-stream metabolites (DHA, AD, 11-deoxycortisol and glucocorticoids) would suggest that IGF-I induced stimulation of the 17-, 21- and 11β-hydroxylases.

The responses to ACTH stimulation of cells which 4 days previously had been pre-treated with an initial and single dose of IGF-I and/or ACTH emphasized the impact of IGF-I on the 3-hydroxylation steps in cortisol biosynthesis. Compared with ACTH pre-treatment, the effects of which faded in the long term, pre-treatment with IGF-I resulted in a significantly increased steroidogenic response (P between < 0.05 and < 0.01). With the single exception of pregnenolone (43% ± 4.7), production of all the metabolites was amplified: 17-OH-Preg: 348% ± 88; DHA: 643% ± 127; 17-OH-P: 193% ± 36; AD: 725% ± 200; 11-deoxycortisol: 573% ± 110; cortisol: 1000%.

Our findings strongly suggest that IGF-I plays a major rôle in the regulation of steroidogenesis by promoting and maintaining enzymatic activity (17, 21- and 11β-hydroxylases) via which the function of ACTH is achieved, viz., biosynthesis of cortisol.     

Effect of marathons on neuromuscular excitability; comparison of electromyographic and biochemical findings

The aim of this paper is to study the neuromuscular excitability of a group of marathon runners and to see how it can be modified right after the marathon. Spontaneously appearing multiplets in EMG signal under ischaemia served as a test of the neuromuscular hyperexcitability. The percentage of positive tests is much higher than in the control population; as a rule, the effect of the marathon is to diminish the neuromuscular hyperexcitability. The concentrations of Ca, Mg and P in the plasma as well as the globular concentration of Mg have been determined several times, both before and after the marathon; no correlation has been found with the neuromuscular hyperexcitability.     

Exhaustive screening of the 21-hydroxylase gene in a population of hyperandrogenic women

21-hydroxylase (21-OH) deficiency accounts for the vast majority of nonclassic (NC) forms of congenital adrenal hyperplasia (CAH), and is associated with symptoms detectable either in childhood (precocious puberty) or sometimes only later in adulthood (hirsutism, acne, amenorrhea). While the severe forms of the disease responsible for salt wasting or simple virilization have been extensively studied, the NC 21-OH deficiency is less well characterized, especially in adults. We studied the 21-OH gene (CYP21) in a population of 69 unrelated hyperandrogenic subjects suspected to be homozygous or heterozygous for NC 21-OH deficiency, based on basal and adrenocorticotrophin (ACTH)-stimulated plasma 17-hydroxyprogesterone (17-OHP, 17-OHPSI) and 21-desoxycortisol (21-DOF, 21-DOFSI) levels. To identify all mutations involved, determination of the whole gene sequence, including exons, exon-intron junctions, and promoter region, was performed, followed by a study of large rearrangements and identification of compound heterozygotes. Alterations were identified in at least one allele of 55 hyperandrogenic subjects. Two NC alterations, Val282Leu and Pro454Ser, were detected in 68% and 7% of the affected alleles, respectively, whereas mutations involved in severe forms were identified in 21% of them. These results document the utility of a molecular diagnosis in hyperandrogenic women suspected of being either heterozygous or homozygous for NC 21-OH deficiency and clearly indicate the importance of genetic counseling in such a population. Received: 9 April 1997 / Accepted: 20 June 1997     

Development of a new sensitive and specific time-resolved fluoroimmunoassay (TR-FIA) of chlormadinone acetate in the serum of treated menopausal women

We describe the development of a serum chlormadinone acetate (CMA) time-resolved fluoroimmunoassay (TR-FIA). We prepared haptens (3-CMO-chlormadinone acetate and 6-chloropregna-4,6-dien-17,20-diol-3-one-20-hemisuccinate), biotinylated tracers (3(biotinylaminopropylamido) 3-CMO-chlormadinone acetate and 3-(6-chloropregna-4,6-dien-17,20-diol-3-one-20-hemisuccinylamino)1-biotinylaminopropane), and immunogens necessary for eliciting two antibodies (anti-chlormadinone acetate 3-CMO/BSA and anti-chlormadinone 20-hemisuccinate/BSA). The specificity of the assay was rigorously studied to eliminate possible interference by polar metabolites of CMA, particularly 17 alpha-acetoxy-6-chloro-3beta-hydroxypregna-4,6-diene-20-one (3beta-hydroxy metabolite), employing an easy-to-use ethylene glycol chromatographic step prior to immunoassay, so as to separate the polar metabolites, in particular the 3beta-hydroxy-CMA metabolite, from the intact CMA. The choice of the anti-CMA antibody was guided by the high assay sensitivity obtained with the anti-CMA 3-CMO/BSA antibody. The detection limit was 51pg/ml. Interassay reproducibility CVs were between 2.6 and 4.5%. This TR-FIA thus appeared to be a sensitive, specific, precise, and consequently well-suited method for measurement of serum CMA during a pharmacokinetic study in women.     

Plasma 17-OH pregnenolone: comparison of a time-resolved fluoroimmunoassay using a new tracer 17-OH pregnenolone-3-oxyacetyl-biotine with a radioimmunoassay using 125I 17-OH pregnenolone-3-hemisuccinate-histamine

In this article we described, for the first time to our knowledge, the development of a new non isotopic immunoassay (time resolved-fluoroimmunoassay) for determining 17alpha-hydroxypregnenolone levels in plasma or serum. This steroid is indeed the most relevant steroid for the diagnosis of 3beta-hydroxysteroid dehydrogenase deficiency. For the hapten tracer, we synthesized a biotin-oxyacetyl 17-hydroxypregnenolone conjugate. A specific polyclonal rabbit anti-17-hydroxypregnenolone was indirectly bound via an immobilized sheep anti-rabbit antibody on microtiter plate wells. The amount of biotin-17-hydroxypregnenolone conjugate bound was then measured by adding Streptavidin-Europium, and the Europium fluorescence was quantified by Time Resolved -Fluorescence (TR-FIA, Delfia System). The plasma 17-hydroxypregnenolone levels of this non isotopic assay were comparatively measured with a radioimmunoassay previously published and using the same anti 17-hydroxypregnenolone antibody. In both cases, the assays were performed after a extraction step and a chromatographic step. The sensitivity of this 17-hydroxypregnenolone time resolved-fluoroimmunoassay was higher than that of 17-hydroxypregnenolone radioimmunoassay. The compared results of plasma 17-hydroxypregnenolone, performed with these two methods were not significantly different. A practical advantage is the stability of the biotine tracer, comparatively to the radioactive 125I 17-hydroxypregnenolone tracer which requires a new labeling every two months.     

Highly sensitive and specific time-resolved fluoroimmunoassay (TR-FIA) of cyproterone acetate and free cyproterone

We have developed a non-isotopic TR-FIA for Cyproterone acetate and Cyproterone in plasma. Synthesis of the biotinylated tracers, biotinylated Cyproterone acetate, and Cyproterone, as well as the preparation of anti–Cyproterone acetate and anti-Cyproterone antisera are reported. The specificity of anti-Cyproterone acetate antiserum resulting from the coupling of link bridge (link bridge between steroid and BSA), on the 3-position on the steroid skeleton, allowed to carry out the Cyproterone acetate assay directly on extracted plasma (without chromatography). On the other hand Cyproterone assays require a purification step, including extraction plus chromatography, because the plasma Cyproterone acetate concentrations in Cyproterone acetate-treated women are 200 times higher than for Cyproterone. Theses plasma TR-FIA of Cyproterone acetate and Cyproterone presented the advantage of needing only small doses of radioactivity for recovery controls, and better praticability related to the only existing RIA described to date.     

Bacterial Activity and Preservation of Sedimentary Organic Matter: The Role of Exopolymeric Substances

Although exopolymeric substances (EPS) are associated with the microorganisms contributing to the production/degradation of sedimentary organic matter, their role in theses processes have so far never been mentioned. Using high-resolution microscopical tools (scanning and transmission electron microscopy, atomic force microscopy), fossil organic matter in the Miocene Monterey Formation (California) and Kimmeridgian laminites (France) has been compared with its present-day analogs, i.e., respectively sulphuroxidizing bacteria and cyanobacterial biofilms. This comparison shows that, particularly in the case of Kimmeridgian cyanobacterial mats deposited in a shallow back-reef environment, organic matter preservation is conditioned by exopolymeric substances secreted by bacteria. A model is proposed for the evolution through time of exopolymeric substances in relation to the mechanical constrains they have been exposed to, during lithification and diagenesis. This model is based on the microscopical observation of sulphuroxidizing bacteria and could explain the morphology of fossil organic matter usually referred to as “amorphous” in standard light microscopy. The highly hydrated nature of exopolymeric substances helps to protect organic matter from degradation and remineralization. These substances can be observed only in microscopy and are undetectable through organic geochemical methods, hence the need to combine these two methods in organic matter studies. Consequently, exopolymeric substances must be considered as an important contributing agent to organic matter preservation. These results confirm the complexity of the bacterial role in geoenvironments and add a new parameter in the productivity-vs-preservation debate.     

Pharmacology of an antiandrogen, anandron, used as an adjuvant therapy in the treatment of prostate cancer

To improve the inhibition of prostate cancer growth obtained by surgical or chemical castration (estrogens or LHRH analogs), blockade of the action of residual androgens of adrenal origin has been proposed. Among antiandrogens acting through the androgen receptor (AR), the nonsteroid anandron (RU 23908) has several advantages over available compounds: megestrol acetate and cyproterone acetate, both steroids, bind substantially to other hormone receptors (progestin, gluco- and mineralocorticoid); and anandron binds only to AR. The nonsteroid flutamide is a prodrug converted to the active metabolite, hydroxyflutamide; anandron is well absorbed on oral administration of an active dose and intact compound disappears slowly from plasma. This may explain why, although in vitro anandron interacts very transiently with AR, in vivo a high level of untransformed anandron is present at the receptor site to induce its antiandrogenic activity. Animal experiments confirm that anandron can counteract the effect of adrenal androgens and inhibit the LHRH analog-induced initial increase in androgen ("flare-up"). Thus, in rats castrated either surgically or by buserelin or DES and supplemented with adrenal androgens (since endogenous adrenal secretion is very low in this species compared to man), anandron decreased prostate weight to control levels. The administration of buserelin to intact rats over 15 days resulted in a significant increase in prostate weight between Days 1 and 5. The addition of anandron to the buserelin inhibited this increase and, furthermore, led to a far greater decrease in prostate weight than that due to buserelin alone at 15 days, indicating a synergy of action.     

Value of 17-hydroxyprogesterone determination in exploration of adrenal cortex enzyme deficiencies]

17-hydroxyprogesterone (17-OH-P) was measured in various populations by radioimmunoassay, using a highly specific antibody produce in the rabbit. Dynamic tests were performed with ACTH, dexamethasone and estroprogestative drugs and the role played by the adrenals and the ovaries in 17-OH-P production could be assessed. 17-OH-P determination is of interest in that, it allows the diagnosis of 21-hydroxylase deficiency, where values above 10 ng/ml are often found. Associated with the measure of testosterone and delta 4-androstenedione, it is also useful in the management of the disease. In the mild form of congenital adrenal hyperplasia with late revelation of the symptoms, determination of 17-OH-P following ACTH stimulation allows of relative diagnosis.     

Metabolic effects of combined cyproterone acetate and percutaneous 17 beta oestradiol after six and twelve months therapy in 61 patients

The metabolic effects of combined cyproterone acetate (50 mg) and percutaneous 17 beta oestradiol were studied during one year in 61 patients admitted for hyperandrogenia. Before treatment and at 6 and 12 months the following tests were performed: oral glucose tolerance test (OGTT) with insulinemia dosage, determination of total cholesterol, LDL, VLDL and HDL fractions, triglycerids, A1 and B apoproteins, liver function tests: bilirubinemia, alkaline phosphatases, transaminases and gamma glutamyl transferases. The patients' mean age was 27.0 +/- 6.8 years, the body mass index was 22.4 +/- 3.5 kg/m2. After one year of treatment the body mass index was not modified. Blood glucose slightly increased during OGTT; at 6 months this was significant at +30 minutes, at 12 months at +30, +60 and +90 minutes (P less than 0.05). There was no variation in insulinemia during OGTT. Total cholesterol decreased significantly at 6 and 12 months (P less than 0.001), this was associated with a decrease in HDL cholesterol, but without modification of the LDL + VLDL/HDL ratio. Decrease in HDL cholesterol was associated with a significant decrease in A1 apoproteins. No change in triglycerids and in liver function tests was observed at either date. In conclusion the metabolic effects of this association are described. These effects are minimal compared to those observed with cyproterone acetate and ethinyl oestradiol association in the literature. However, attention should be drawn to the possibility of glucose intolerance and decrease in HDL cholesterol and A1 apoproteins.