IGF-1 Levels, Complex Formation, and IGF Bioactivity in Growth Hormone-Treated Children With Prader-Willi Syndrome.

CONTEXT: Children with Prader-Willi syndrome (PWS) attain high-serum immunoreactive IGF-1 levels during a standard-dose GH treatment, which leads to concern, but lowering the dose deteriorates their body composition. OBJECTIVE: The objective of the study was to evaluate serum IGF-1, IGF binding protein (IGFBP)-3, and acid-labile subunit (ALS) levels, complex formation, and IGF bioactivity in GH-treated PWS children. DESIGN: This was a cross-sectional study. SETTING: The setting of the study was a Dutch PWS cohort. PARTICIPANTS: Forty GH-treated PWS children compared with 41 age- and sex-matched healthy controls participated in the study. INTERVENTIONS: Interventions included GH treatment (1.0 mg/m(2) · d = ∼0.035 mg/kg · d). MAIN OUTCOME MEASURES: Serum IGF-1, IGFBP-3, and ALS levels, complex formation, and IGF bioactivity by IGF-1 receptor kinase activation assay were measured. RESULTS: Serum IGF-1, IGFBP-3, and ALS levels and IGF-1 to IGFBP-3 ratio were significantly higher in GH-treated PWS children than in healthy controls. The 150-kDa ternary complex formation was, however, also significantly higher than in controls, indicating that most of serum IGF-1 is sequestered in the ternary 150-kDa complex with ALS and IGFBP-3. Young GH-treated PWS children [median (interquartile range) aged 5.2 (4.3-7.2) y] exhibited higher serum IGF bioactivity than controls, but no difference was observed in IGF bioactivity between older GH-treated PWS children, aged 14.9 (13.8-16.2) years, and controls. The proportion of IGF bioactivity of total serum IGF-1 was, however, lower in GH-treated PWS children than in controls. Serum immunoreactive IGF-1 levels did not correlate with IGF bioactivity in GH-treated children with PWS, in contrast to a strong positive correlation in healthy controls. CONCLUSIONS: In GH-treated PWS children, most serum IGF-1 is sequestered in the 150-kDa complex. Higher IGF bioactivity was found only in young GH-treated PWS children and not in the older ones. IGF bioactivity during GH showed a wide variation, and there was a disrupted correlation with immunoreactive IGF-1 levels, which makes immunoreactive IGF-1 levels an inappropriate indicator for GH dosing in PWS children.

Column chromatographic characterization of complex formation of pro-IGF-II isoforms with acid labile subunit and IGF-binding proteins associated with non-islet cell tumour induced hypoglycaemia.

OBJECTIVE AND DESIGN: Non-islet cell tumour induced hypoglycaemia (NICTH) is a paraneoplastic phenomenon that is associated with the formation of several isoforms of pro-insulin like growth factor 2 (pro-IGF-II), or so called "big" IGF-II. Disturbance of ternary complex formation by big IGF-II is assumed to be a crucial early event in the pathogenic cascade of hypoglycaemia. By size-exclusion chromatography, we investigated complex formation by adding different naturally occurring isoforms of pro-IGF-II to pooled normal adult serum. Results were compared with the analysis of the serum from a patient with NICTH. RESULTS: Gel filtration experiments with the serum of a patient with NICTH demonstrated that ternary complex formation was severely compromised. The various forms of pro-IGF-II did not induce a shift of IGF-binding protein 3 (IGFBP-3) from 150kD towards smaller binary complexes in the normal adult serum, suggesting that they did not interfere with the interaction between the acid labile subunit and IGFBP-3. Instead, unglycosylated recombinant pro-IGF-II[1-104] was capable of forming a 150kD complex. In contrast, predominantly glycosylated and unglycosylated pro-IGF-II[1-87] eluted in the free unbound form. We showed that mature IGF-II and isoforms of pro-IGF-II were able to phosphorylate the IGF-I receptors of MC7 cells, albeit to a markedly lesser extent than IGF-I. When the patient's serum was tested in this system, the IGF-I receptor phosphorylation activity was considerably less than that in sera from age matched healthy individuals. CONCLUSION: We postulate that, alongside the presence of big IGF-II in the circulation, additional steps are required to stimulate the release of IGF-II and pro-IGF-II isoforms from IGFBPs in vivo. These factors may be proteases, that are present in the local environment of the tumour and in insulin-sensitive tissues.

Is aromatase cytochrome P450 involved in the pathogenesis of endometrioid endometrial cancer?

Prospectively, the relationship between androgen levels in the utero-ovarian circulation, aromatase activity in endometrial and body fat tissue, and the presence or absence of endometrioid endometrial cancer was studied in postmenopausal women. In 43 women with endometrioid endometrial cancer and 8 women with a benign gynecological condition, a hysterectomy with bilateral salpingo-oophorectomy was performed. Using tritium water-release assays, aromatase activities in endometrial and body fat tissue were determined and related to the steroid levels from the peripheral and the utero-ovarian venous circulation (estradiol, androstenedione, testosterone) and to the presence or absence of endometrial cancer. Significant aromatase activity was found in both benign and malignant endometrial tissue samples. Aromatase activity in samples of endometrial tissue and in samples of body fat did not correlate with steroid levels in peripheral or utero-ovarian venous blood. Aromatase activity in samples of benign or malignant endometrium did not differ. Remarkably, in four women with mainly poorly differentiated endometrial cancer, very high aromatase activity was found in endometrial tissue. It is likely that multiple pathogenetic pathways exist that eventually lead to the formation of endometrioid endometrial cancer. The local availability of androgens and the finding that aromatase activity is present in both endometrial cancer and benign endometrial tissue support the hypothesis that aromatase activity in the endometrium may play a role in malignant transformation by converting androgens into mitogenic estrogens in the endometrial tissue.

Effect of tibolone (Org OD14) and its metabolites on aromatase and estrone sulfatase activity in human breast adipose stromal cells and in MCF-7 and T47D breast cancer cells.

Tibolone (Org OD14) is a synthetic steroid used for post-menopausal hormone replacement therapy (HRT). Since HRT might increase breast cancer risk, it is important to determine the possible effects of tibolone on breast tissues. Tibolone and its metabolites Org 4094, Org 30126 and Org OM38 have been reported to inhibit estrone sulfatase activity in MCF-7 and T47D breast cancer cell lines, which suggest beneficial effects on hormone dependent breast cancer by reducing local production of free estrogens. Breast adipose stromal cells (ASCs) contain aromatase activity-an obligatory step in the biosynthesis of estrogens-and possibly contain sulfatase activity. We investigated the effects of tibolone, its metabolites and the pure progestin Org 2058 on PGE(2)-stimulated aromatase activity and on sulfatase activity in human ASC primary cultures and on sulfatase activity in MCF-7 and T47D cell lines. In MCF-7, tibolone and metabolites, but not Org 2058, were found to inhibit sulfatase activity. In T47D, tibolone inhibited sulfatase only at 10(-6)M, although weakly. ASC had high sulfatase activity, which was inhibited by 10(-6)M of tibolone, Org 4094 and Org 30126, but not by Org OM38 or Org 2058. Surprisingly, aromatase activity in ASC was increased by both tibolone and Org 2058 at 10(-6)M. As ligand binding assay results and immunohistochemistry indicated the absence of progesterone and estrogen receptors in ASC, these effects on aromatase and sulfatase activity in ASC likely take place by other routes. Because tibolone and its metabolites inhibit sulfatase activity, and because tibolone only increases aromatase activity at a high concentration, we conclude that effects of tibolone on the breast are probably safe.

Progesterone receptor, bc1-2 and bax expression in meningiomas.

Meningiomas are generally benign central nervous system neoplasms, which frequently express progesterone receptor (PR) and only rarely express the estrogen receptor (ER). For breast cancer, a relation between steroid hormone receptors and proteins involved in the apoptotic process has been described. For meningiomas, the exact relation between PR and these proteins is not known. In this study, ER, PR, bcl-2 and bcl-2-associated x protein (Bax) expression levels were determined in meningioma cytosols. As a reference for our experimental conditions, we also determined these proteins in breast cancer cytosols. PR and ER were determined with a ligand-binding assay and scatchard-plot analysis. The expression levels of the anti- and pro-apoptotic proteins, bcl-2 and Bax, respectively, were determined by immunoblotting. In 65% of the meningioma, bcl-2 expression was found in variable amounts. In contrast to breast cancer, a significant negative association between PR and bcl-2 was found (P < 0.01). Bax expression appeared constitutive, not related to PR, and 2.6 times higher than breast cancer. As both PR and bcl-2 appear positively associated with prognosis, the negative relationship between bcl-2 and PR found in this study might have some biological and clinical significance.

Progesterone receptor isoform expression in human meningiomas.

The majority of meningiomas express the progesterone receptor (PR), and therefore meningiomas are considered to be progesterone-responsive. In addition, an association has been reported between PR and prognosis. At least two PR isoforms exist, PR-B (116--120 kDa) and PR-A (81 kDa), each of which are likely to have different biological functions. Knowledge of the differential expression of both isoforms is necessary to understand the effects of progesterone on meningioma growth. Therefore, in this study, PR-A and PR-B expression levels were determined in 61 human meningiomas by immunoblotting. Total PR expression levels were determined with a ligand binding assay (LBA) (total PR(LBA)). Both PR isoforms and an additional PR 78 kDa protein (PR-78) were expressed in the meningiomas. Meningiomas expressing more PR-A than PR-B had significantly higher total PR(LBA) levels (P<0.001). The PR-78 band intensity was negatively associated with that of PR-B (r(s)=-0.76, P<0.0001). PR-78 may represent an endogenous degradation product, but a similar regulation pathway in the biogenesis of both PR-B and PR-78 is not excluded. Meningiomas contain both PR isoforms, but in highly variable ratios and this variability may have some biological significance. Most meningiomas express more PR-A than PR-B. Therefore in meningioma, assuming that PR-B is more transcriptionally active than PR-A, progesterone responsiveness could be based on transrepression rather than on transactivation of target genes, and progesterone blockade may only be effective in certain subsets of meningiomas.

Levels of estrogen and progesterone receptors in the myometrium and leiomyoma tissue after suppression of estrogens with gonadotropin releasing hormone analogs.

Gonadotropin releasing hormone (GnRH) agonists are successfully used in the treatment of uterine leiomyomas. Different GnRH agonists may have different local effects on steroid receptors. This study was designed to evaluate potential differences in this respect between triptorelin (Decapeptyl) and goserelin (Zoladex) in a randomized controlled multicenter study using untreated patients during the luteal phase of their menstrual cycle as controls. Estrogen receptors (ERs) and progestin receptors (PRs) were measured by ligand binding assay in myoma and myometrium tissue following a 4-month treatment course with one of the GnRH analogs. In 18 untreated patients median values of ER and PR contents were comparable in myoma and myometrium: for ER at median levels of 56 and 43 fmol/mg protein, respectively; and for PR, median binding capacities were 690 and 730 fmol/mg protein, respectively. Both types of GnRH treatment (total number of patients 34) were associated with significant rises in ER in myoma (to a median level of 279 fmol/mg protein, p<0.001) and myometrium (to a median level of 109 fmol/mg protein, p<0.01). The increase in ER in myomas was significantly (p<0.001) greater than in myometria of the same patients (n=30). After treatment, PR in myomas (median level 520 fmol/mg protein) did not change significantly, but a significant (p<0.05) decrease was found for myometria (median level of 320 fmol/mg protein). Thus, ER and PR concentrations in myoma and myometrium are comparable before treatment, but estrogen suppression with GnRH analogs leads to a larger increase of ER level in leiomyomas than in myometrium, without an effect on PR, whereas myometria had lower PR levels. Therefore, leiomyoma reacts differently from myometrium towards lowered steroid concentrations in the circulation. Since the PR is considered to be a marker of estrogenic stimulation, this indicates remaining estrogenic effects on leiomyomas despite the large decrease of plasma estrogen concentrations.

Intersubject responsiveness of high-affinity growth hormone (GH)-binding protein (GHBP) to long-term GH replacement therapy.

In adult growth hormone deficiency (GHD) syndrome responsiveness to GH replacement therapy is reported to vary considerably. The underlying mechanisms, however, are not well understood. The aim of this study was to investigate which baseline variables determine the reported variable intersubject responsiveness of high-affinity GH-binding protein (GHBP) to GH replacement therapy. In the setting of a double blind study over 12 months with placebo control over the first 6 months, we analyzed the interrelationship between a number of baseline variables, which vary considerably amongst subjects, and the GHBP response to GH replacement in 31 GHD adults (21 males and 10 females). The following variables were investigated: age, gender, duration of GHD, body composition, serum levels of high-affinity GHBP, insulin-like growth factor-1 (IGF-1), and IGF-binding protein-3 (IGFBP-3). The results showed that in the 6 months treated group of 16 patients (11 males, 5 females), serum IGF-1 increased from 87 ng/ml (range: 26 to 173) to 250 (range: 62 to 467) (p<0.01) and GHBP increased from 1,302 pmol/l (range: 845 to 1,m960) to 1418 (range: 941 to 2,025) (p=0.04). Both parameters showed a significant time effect (within-subjects) (p<0.001). In the 12 months treated group of 15 patients (10 males, 5 females), serum IGF-1 increased from 92 ng/ml (range: 20 to 180) to 272 (range: 45 to 491) (p<0.01), whereas GHBP did not show a significant change: from 1,186 pmol/l (range: 660 to 1,690) to 1,252 (range: 580 to 1,890) (p=0.87). Also no significant time effect (within-subjects) was observed for GHBP (p=0.06). Step-wise multiple regression analyses revealed that during the 6 months placebo period baseline GHBP explained 83% of the variance in post-placebo GHBP, whereas the variance in post-treatment GHBP could be accurately predicted (adjusted R2=0.93) from baseline GHBP and body fat mass, irrespective of the duration of GH treatment. No other baseline variables contributed independently to the GHBP response, with the exception of IGFBP-3, which showed a small, but significant contribution in females, but not in males. These findings indicate that the variable intersubject responsiveness of GHBP to GH replacement therapy is mainly due to differences in baseline body fat mass amongst adult GHD patients, and that in female patients a relatively low baseline IGFBP-3 contributes to a rise in serum GHBP after GH treatment. The clinical relevance of measuring GHBP in adult GHD patients is limited to the first screening step to diagnose GHD, because long-term GH therapy tends to restore serum GHBP to pretreatment levels.

Intratumoral levels of estrogens in breast cancer.

Breast cancer tissue is an endocrine organ and particularly the estrogen biosynthetic properties of this tissue have been well studied. The concentration of estradiol in breast cancer tissue from postmenopausal patients is considerably higher than that in the circulation and appears to depend largely on local production. Androgenic precursor steroids are abundantly present, but estrogen storage pools like fatty acid derivatives appear to be less important than initially thought. New, potent and highly specific aromatase inhibitors effectively inhibit peripheral conversion of androgens to estrogens (Cancer Res. 53: 4563, 1993) as well as intratumour aromatase, median aromatase activity being 89% lower in the tissue from patients pretreated with aromatase inhibitor 7 days prior to surgery (P < 0.001). Also the intratissue concentrations of estrogens were decreased (64% and 80% reduction, respectively for estrone and estradiol; P = 0.001 and <0.05; Cancer Res. 57: 2109, 1997). These results illustrate that intratissue estrogen biosynthesis is effectively inhibited by the new generation of aromatase inhibitors. The pathophysiological consequences of this finding are currently under study.

Biochemical and histological effects of vaginal estriol and estradiol applications on the endometrium, myometrium and vagina of postmenopausal women.

Estrogen and progesterone receptors in the cytosol (ERc, PRc) and estrogen receptors in the nuclear compartment (ERn) were measured in the endometrium, myometrium and vagina of 29 postmenopausal women who underwent hysterectomy. The effects of vaginal estriol (0.5 mg daily) compared to 17 beta-estradiol (0.05 mg daily) therapy on these receptor levels were studied. In addition, the endometrium was examined by light microscopy for estrogenic stimulation. We found biochemical and histological signs of estrogenic stimulation in all three tissues after estradiol as well as estriol therapy. In the vagina the effect of both estrogens on the ERc concentration was different from that in the endometrium and myometrium. The effects of estradiol and estriol on the ERn were comparable in all three tissues. The PRc levels increased significantly in all tissues after estrogen therapy; in the myometrium it was significantly higher after estriol than after estradiol applications. In conclusion, there were no clear differences between vaginal estradiol and estriol medication with regard to the effects on receptor levels in vaginal and uterine tissues. In the histological studies at the light microscopy level similar signs of estrogen stimulation of the endometrium were found following estradiol and estriol medication.

Oestrogen receptor independent expression of progestin receptors in human meningioma--a review.

Human meningiomas are rich in progestin receptors (PR), which are expressed in this tissue in an oestrogen independent fashion. In the search for an explanation of this observation, the existence of a protein in human meningioma cytosol which is capable of binding to a synthetic oestrogen responsive element (ERE) has been demonstrated. Using reverse transcriptase, PCR mRNA encoding for the wild-type oestrogen receptor (ER) was found. In addition, several splice variants of ER mRNA have been identified in human meningioma tissue, including variants lacking exons 4, 5 and 7. We found the ER delta 4 protein to have no transcriptional activity and the ER delta 7 protein reportedly is dominant negative. These mutants therefore probably are not responsible for the autonomous PR synthesis in human meningioma. The ER delta 5 protein, by contrast, has been reported to have oestrogen independent transcriptional activity and it is tempting to speculate that this protein is similar or identical to the ERE binding protein we have found in human meningioma. The role of wild type ER mRNA is presently unclear. Activation of other signal transduction pathways in meningioma does not lead to an increased PR concentration. The promoter area of the meningioma PR gene should be investigated for the possible sensitivity to other transcription factors.

Functional analysis of an alternatively spliced estrogen receptor lacking exon 4 isolated from MCF-7 breast cancer cells and meningioma tissue.

An alternatively spliced mRNA coding for a variant estrogen receptor (ER) missing exon 4 (ERdelta4) was detected in the breast tumor cell line MCF7 and meningioma tissue by using the reversed transcriptase PCR technique. The trans-activational properties of this mutant ER were assessed in embryo carcinoma P19EC and human choriocarcinoma JEG3 cells by co-transfection of the ERdelta4 expression vector with an oxytocin promoter construct containing an estrogen-responsive element. ERdelta4 did not trans-activate the oxytocin promoter in either a hormone-dependent or -independent manner. Co-transfection of ERdelta4 together with the wtER did not show any interference of ERdelta4 on the stimulation of the oxytocin promoter by the wtER. ERdelta4 was translated in vitro. Its capacity to bind estradiol, and the binding of the variant to a synthetic estrogen-responsive element were compared to those of the wild-type receptor. ERdelta4 did not bind to a synthetic estrogen-responsive element, nor did it bind estradiol. Hence, ERdelta4 appears to be a silent variant and we speculate that it is without any role in tumor progression.

High affinity growth hormone binding protein in plasma of patients with acromegaly and the effect of octreotide treatment.

OBJECTIVE: The objective of this study was to investigate the effect of plasma GH-levels on the high affinity growth hormone binding protein (GHBP). PATIENTS: We studied plasma samples of eight patients with acromegaly and eight age and sex matched healthy subjects. DESIGN: Patients with acromegaly were treated with octreotide administered by continuous subcutaneous infusion. Levels of growth hormone binding protein (GHBP) were measured in plasma samples before therapy and 3, 6 and 12 months after starting treatment. During this period, octreotide was administered in doses of 300-800 micrograms/day. The mean dose per patient over the study period ranged from 300 to 575 micrograms/24 h. The GHBP levels of patients with acromegaly were compared with those in the healthy subjects. MEASUREMENTS: Bound and free 125I-GH in plasma were measured using FPLC gel chromatography on a Superose 12 column, after an overnight incubation period. The binding data were used for a Scatchard plot analysis. Wilcoxon's signed rank test was used for statistical analysis. RESULTS: We found lower GHBP levels in acromegalic patients (P = 0.01) than in the control subjects. Octreotide treatment resulted in IGF-I levels < 300 micrograms/l in four patients. In these patients GHBP levels increased. CONCLUSIONS: We conclude that growth hormone binding protein levels are down regulated in acromegaly, indicating an important role for GH in the regulation of this protein.

Tissue androgens and the endocrine autonomy of breast cancer.

To evaluate whether a tumour-directed gradient in androgen levels in fatty tissue can account for the maintenance of intra-tissue oestradiol levels, androstenedione (Adione), dehydroepiandrosterone (DHEA), testosterone (Testo) and androstenediol (Adiol) were assayed in breast tumour tissues and in fatty tissue taken at different distances from the tumour. The concentration of Adione was significantly lower in tumour tissue (5.6 +/- 1.5 pmol/g tissue; mean +/- SEM; n = 14) than in the adjacent fatty tissue (20.4 +/- 2.2; P less than 0.005). Testo, by contrast, occurred in equal concentrations in tumour (0.80 +/- 0.11) and in adjacent fatty tissue (0.70 +/- 0.07). Adione levels tended to be lower after the menopause only in fatty tissue, not in the tumour tissue; for Testo no differences were observed between samples from pre- and postmenopausal patients. Tumour DHEA levels (57 +/- 12 pmol/g tissue) were lower than those in fatty tissue (117 +/- 17; P less than 0.02). As with Adione, fatty tissue DHEA concentrations tended to be higher in pre- than in postmenopausal patients. Adiol showed a similar pattern as Testo. For none of the aromatase substrates nor their precursors a tumour-directed gradient was observed. The concentration of Adione in breast cancer tissue is much lower than the reported Km of the aromatase system for Adione. We have concluded, therefore, that the maintenance of oestradiol concentrations in tumour tissues is not substrate-driven.

On the significance of in situ production of oestrogens in human breast cancer tissue.

We have previously shown that human breast cancer is autonomous in the regulation of its intra-tissue oestradiol concentration. Breast fatty tissue does not have this capacity, but rather reflects changes in the peripheral oestradiol concentration. To further evaluate the relative contribution of breast cancer and fatty tissue to the maintenance of tumour oestradiol we investigated whether a tumour-directed gradient in aromatase activity and oestrogen levels existed in mastectomy specimens. No such gradient was found, however, for aromatase, oestrone, oestradiol and their sulphates. Aromatase activity (expressed per gram of tissue) and the concentrations of oestradiol, oestradiol sulphate and oestrone sulphate were higher in tumour than in breast fatty tissue. Fatty tissue had a higher oestrone concentration. It is tentatively concluded that breast tumour aromatase activity is more important for the maintenance of tumour oestradiol levels than aromatase in breast fatty tissue.

Endogenous steroid hormones and local aromatase activity in the breast.

To test the hypothesis of an increased activity of the enzyme aromatase in adipose tissue from affected when compared with non-affected quadrants of patients with breast cancer, the aromatase activity has been measured in tumour and fatty tissues dissected at specific sites from the breasts of 16 patients. Activity was measured after extensive purification of the product formed. Results, expressed in fmol/g of tissue, did not show a higher activity in the affected vs the non-affected quadrants. In the tumours, higher activities were found when expressed per g of tissue. Per mg of DNA, an indicator of the number of cells, tumour enzymatic activity was lower than in fatty tissues. The relations between the products of aromatase, oestrone and oestradiol in the various tissues point to the importance of additional enzymatic processes, especially of the reductive 17 beta-oestradiol dehydrogenase, in the accumulation of high quantities of oestradiol in the malignant tissue.

Oestrogen concentrations in plasma, endometrium, myometrium and vagina of postmenopausal women, and effects of vaginal oestriol (E3) and oestradiol (E2) applications.

Oestradiol (E2), oestriol (E3) and oestrone (E1) levels were measured in plasma and endometrium, myometrium and vagina of 29 postmenopausal women who underwent hysterectomy. The influence of vaginal E3, compared to vaginal E2 therapy at a dose one-tenth that of E3 on the basal steroid levels was examined. We found (1) no correlation between basal tissue and plasma concentrations of the oestrogens in untreated postmenopausal women, however, after vaginal E3 therapy we did find a positive correlation between them, (2) E2 to be the oestrogen in the highest basal concentration in endometrium and myometrium as well as in the vagina, (3) higher basal concentrations of all three oestrogens in endometrium compared to myometrium and vagina, (4) a long term (at least 12 h) elevation of the plasma and tissue E3 concentrations after vaginal E3 therapy (0.5 mg per day), (5) no significant changes of the plasma and tissue E2 concentrations after 0.05 mg per day vaginal E2 therapy, measured 12 h after the last application and (6) no signs of a difference between vagina and uterus in uptake and retention of E3 or E2. In conclusion, there was no difference on this level of mechanism of action in vagina and uterus which can account for the supposed vaginotrophicity and non-uterotrophicity observed with E3 but not E2.

Identification of 16 alpha-hydroxy-estrone as a metabolite of estriol.

During a study on the uptake and retention of estrogens by uterine tissues in postmenopausal women, evidence was obtained of the presence of a metabolite of estriol, tentatively identified as 16 alpha-hydroxy-estrone (16-OHE1). In view of the recent hypothesis concerning the role of 16-OHE1 as a risk marker for breast cancer, attempts were made to establish the identity of the metabolite. After infusions with labelled estriol, radioactive material with chromatographic properties of 16-OHE1 was observed; insufficient material was obtained for micro-recrystallization. After oral administration of estriol, myometrial tissue was extracted, then purified by chromatography and the appropriate fraction was analyzed by gas chromatography-mass spectrometry, monitored at 3 specific mass units. In the women receiving estriol the presence of 16-OHE1 could be unequivocally demonstrated, the concentrations in the myometrium being 6 and 18 ng/g tissue, whereas less than 0.2 ng/g was found in an untreated patient. This identification of 16-OHE1 does not support the hypothesis about its prominent role in human breast cancer. Additional investigations will be necessary to clarify its role in the process of stimulation of estrogen-sensitive tissues under physiological conditions and after exogenous administration of estriol.

Changes of molecular forms of growth hormone in bromocriptine treated acromegaly in relation to changes of somatomedin-C and clinical response.

Eleven patients with active acromegaly were treated with 10-20 mg bromocriptine daily for a period of 6-9 months. The clinical response was evaluated by a 'clinical and metabolic improvement score'. The biochemical response was evaluated by measurement of both the mean plasma growth hormone (GH) level during the day and the somatomedin-C (Sm-C) concentration. Before and at the end of the treatment period plasma samples were fractionated by Sephadex G-100 chromatography in order to study the effects of chronic bromocriptine treatment on the concentrations of total GH and its different molecular forms. The main observations may be summarized as follows: Three immunoreactive components were observed on Sephadex chromatography corresponding to molecular weight above 100 000 (big-big GH), 40 000-60 000 (big GH) and 20 000-22 000 (little GH). Bromocriptine treatment induced preferentially a reduction of little GH. There was a very good correlation between the decrease of little GH and total GH, and both were significantly correlated with the clinical response. The correlation between the decrease of Sm-C values and that of little and total GH as well as between the decrease of Sm-C and the clinical response was poor. It is concluded that a) measurement of little GH is not superior to the determination of total GH in the assessment of disease activity of bromocriptine treated acromegalic patients; b) both methods are superior to the measurement of plasma Sm-C levels; c) clinical response out of proportion ot the fall of total GH which can be explained by a preferential reduction of little GH, has not been observed in our investigations.

Changes in plasma GH levels and clinical activity during bromocriptine therapy in acromegaly. The value of predictive tests.

Twenty-seven patients with active acromegaly despite previous treatment by surgery and/or radiotherapy received bromocriptine in a dose of 10-20 mg daily for a period of 6-9 months. The results of chronic bromocriptine treatment were evaluated by measurement of plasma growth hormone (GH) levels during the day and by subjective and objective criteria of clinical activity. The results of chronic bromocriptine treatment were also compared with four biochemical criteria obtained before treatment e.g. basal plasma prolactin (Prl) levels and the plasma GH response to oral administration of 2.5 mg bromocriptine respectively iv administration of 200 micrograms TRH and 500 micrograms somatostatin. The main observations may be summarized as follows: 1) The mean pre-treatment GH levels during the day ranged from 6-207 mU/1. Hyperprolactinaemia was present in 6 patients. 2) During bromocriptine treatment mean plasma GH levels decreased to less than 50% in 11 patients (GH responders) whereas in 19 patients changes of mean plasma GH and of subjective criteria of clinical activity were concordant. 3) Glucose tolerance improved significantly (P less than 0.01) in 10 GH-responders and the urinary hydroxyproline/creatinine ratio decreased significantly (P less than 0.05) in 8 GH-responders. 4) Five out of 6 patients with hyperprolactinaemia belonged to the group of GH-responders. 5) A single dose of 2.5 mg bromocriptine induced a more than 50% decrease of plasma GH in 8 of 11 GH-responders and in 5 of 16 GH non-responders.(ABSTRACT TRUNCATED AT 250 WORDS)