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Dive into the research topics where F.H. de Jong is active.

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Featured researches published by F.H. de Jong.


Menopause | 2004

Anti-Müllerian hormone is a promising predictor for the occurrence of the menopausal transition.

I.A.J. van Rooij; I. den Tonkelaar; Frank J. Broekmans; C.W.N. Looman; G.J. Scheffer; F.H. de Jong; Axel P. N. Themmen; E.R. te Velde

Objective: Age at menopause and age at the start of the preceding period of cycle irregularity (menopausal transition) show considerable individual variation. In this study we explored several markers for their ability to predict the occurrence of the transition to menopause. Design: A group of 81 normal women between 25 and 46 years of age visited the clinic two times (at T1 and T2) with an average interval of 4 years. All had a regular menstrual cycle pattern at T1. At T1, anti-müllerian hormone (AMH), follicle-stimulating hormone (FSH), inhibin B and estradiol (E2) were measured, and an antral follicle count (AFC) was made during the early follicular phase. At T2, information regarding cycle length and variability was obtained. Menopause transition was defined as a mean cycle length of less than 21 days or more than 35 days or as a mean cycle length of 21 to 35 days, but with the next cycle not predictable within 7 days during the last half year. A logistic regression analysis was performed, with the outcome measure as menopause transition. The area under the receiver operating curve (ROCAUC) was calculated as a measure of predictive accuracy. Results: In 14 volunteers, the cycle had become irregular at T2. Compared with women with a regular cycle at T2, these women were significantly older (median 44.7 vs 39.8 y, P < 0.001) and differed significantly in AFC, AMH, FSH, and inhibin B levels assessed at T1. All parameters with the exception of E2 were significantly associated with the occurrence of cycle irregularity; AMH, AFC, and age had the highest predictive accuracy (ROCAUC 0.87, 0.80, and 0.82, respectively). After adjusting for age, only AMH and inhibin B were significantly associated with cycle irregularity. Inclusion of inhibin B and age to AMH in a multivariable model improved the predictive accuracy (ROCAUC 0.92). Conclusions: The novel marker AMH is a promising predictor for the occurrence of menopausal transition within 4 years. Adding inhibin B improved the prediction. Therefore, AMH alone or in combination with inhibin B may well prove a useful indicator for the reproductive status of an individual woman.


The Journal of Clinical Endocrinology and Metabolism | 2011

Anti-mullerian hormone predicts menopause: a long-term follow-up study in normoovulatory women

Simone L. Broer; Marinus J.C. Eijkemans; G.J. Scheffer; I.A.L.M. van Rooij; A. de Vet; Axel P. N. Themmen; Joop S.E. Laven; F.H. de Jong; E.R. te Velde; B.C.J.M. Fauser; F.J. Broekmans

CONTEXT It has been hypothesized that a fixed interval exists between age at natural sterility and age at menopause. Both events show considerable individual variability, with a range of 20 yr. Correct prediction of age at menopause could open avenues of individualized prevention of age-related infertility and other menopause-related conditions, like cardiovascular disease and breast carcinoma. OBJECTIVE The aim of this study was to explore the ability of ovarian reserve tests to predict age at menopause. DESIGN AND SETTING We conducted a long-term follow-up study at an academic hospital. PARTICIPANTS A total of 257 normoovulatory women (age, 21-46 yr) were derived from three cohorts with highly comparable selection criteria. INTERVENTIONS Anti-Müllerian hormone (AMH), antral follicle count, and FSH were assessed at time 1 (T1). At time 2 (T2), approximately 11 yr later, cycle status (strictly regular, menopausal transition, or postmenopause) and age at menopause were inventoried. MAIN OUTCOME MEASURES Accuracy of the ovarian reserve tests in predicting time to menopause was assessed by Cox regression, and a nomogram was constructed for the relationship between age-specific AMH concentrations at T1 and age at menopause. RESULTS A total of 48 (19%) women had reached postmenopause at T2. Age, AMH, and antral follicle count at T1 were significantly related with time to menopause (P < 0.001) and showed a good percentage of correct predictions (C-statistic, 0.87, 0.86, and 0.84, respectively). After adjusting for age, only AMH added to this prediction (C-statistic, 0.90). From the constructed nomogram, it appeared that the normal distribution of age at menopause will shift considerably, depending on the individual age-specific AMH level. CONCLUSIONS AMH is highly predictive for timing of menopause. Using age and AMH, the age range in which menopause will subsequently occur can be individually calculated.


Life Sciences | 1992

Adrenal glands of mouse and rat do not synthesize androgens

W.M. van Weerden; H.G. Bierings; G.J. van Steenbrugge; F.H. de Jong; Fritz H. Schröder

Human adrenal glands produce considerable amounts of the C-19 steroids dehydroepiandrosterone (DHEA) and androstenedione. To investigate the capability of rodent adrenals to produce these steroids, cell suspensions of mouse and rat adrenal glands were incubated in the absence and presence of adrenocorticotropic hormone (ACTH). Corticosterone levels in the incubation medium increased dramatically in the presence of ACTH, but no significant amounts of 17-hydroxyprogesterone or androstenedione could be detected. This indicates that the adrenals of rat and mouse lack the enzyme 17 alpha-hydroxylase. Absence of plasma cortisol in the presence of high levels of corticosterone confirmed these data. Plasma levels of androstenedione were significantly decreased in castrated male rats as compared to levels observed in intact males, showing the contribution of the testes to the plasma content of androstenedione. Very low levels of androstenedione were observed in female, male and castrated male mice. Plasma concentrations of DHEA were not detectable in intact and castrated male mice and rats. It is concluded that rat and mouse lack the enzyme necessary to synthesize adrenal C-19 steroids and that the adrenals in these animals, therefore, do not contribute to plasma levels of androstenedione and DHEA.


Journal of Steroid Biochemistry | 1973

Evaluation of a radioimmunoassay for testosterone estimation

H.L. Verjans; B.A. Cooke; F.H. de Jong; C.M.M. De Jong; H.J. van der Molen

Abstract A radioimmunoassay technique, which is essentially a modification of the method described by Furuyama et al.[1], has been evaluated for the determination of testosterone in human peripheral plasma and rat testis tissue. The antiserum used was raised against testosterone-3-(0-carboxymethyl)-oxime-bovine serum albumin in female rabbits. It had an association constant of 5.5 × 109 1/mol, 4°C, at a dilution of 1 in 20,000. The procedure involved addition of [3H]-testosterone internal standard, extraction and chromatography of the plasma extracts on alumina micro-columns prior to assay. Testis tissue extracts were not chromatographed. Known amounts of standard testosterone were subjected to the same procedures. After incubation with antiserum for 16 h at 4°C total recovery from the extraction, chromatography (when used) and incubation procedures were measured in order to correct for losses. Either toluene scintillation fluid, dextran-coated charcoal or polyethylene glycol were used to separate free and bound testosterone. For human plasma as well as for testis tissue a good correlation was observed between results obtained with radioimmunoassay and a gas chromatographic method using electron capture detection of testosterone chloroacetate[12].


Molecular and Cellular Endocrinology | 1992

Activin receptor mRNA expression in rat testicular cell types

J.P. de Winter; Axel P. N. Themmen; Jos W. Hoogerbrugge; I.A. Klaij; J. A. Grootegoed; F.H. de Jong

cDNA encoding the extracellular domain of the rat activin receptor was cloned using the polymerase chain reaction (PCR). This cDNA is highly homologous to cDNA encoding the extracellular domain of the mouse activin receptor, whereas at the protein level the extracellular domains of both receptors are identical. Employing this cDNA as a probe in Northern blot analysis, expression of two activin receptor mRNAs (6 kb and 4 kb) was observed, in testes of immature and mature rats. Between day 21 and 28 of postnatal development, a large increase in testicular expression of the 4 kb mRNA was found, suggesting expression of this activin receptor mRNA in germ cells. The 4 kb mRNA was indeed present in isolated pachytene spermatocytes and round spermatids, but was absent in elongating spermatids. Sertoli cells obtained from immature and mature rats expressed both the 6 kb and 4 kb mRNAs, whereas the expression of these mRNAs in Leydig cell preparations was very low. These results may imply that activin has multiple actions in the control of testicular function.


European Journal of Cancer and Clinical Oncology | 1984

Treatment of metastatic breast cancer patients with different dosages of megestrol acetate; dose relations, metabolic and endocrine effects.

J. Alexieva-Figusch; Marinus A. Blankenstein; W. C. J. Hop; J.G.M. Klijn; Steven W. J. Lamberts; F.H. de Jong; Roel Docter; Herman Adlercreutz; H.A. van Gilse

Megestrol acetate (MA) is of therapeutic value in breast cancer patients. This study was designed to evaluate the effects of different dosages of MA on endocrine events potentially influenced by the drug in relation to plasma level of MA and clinical effects in patients with advanced breast cancer. Eighteen postmenopausal patients were randomly distributed over six groups to receive daily 90, 180 or 270 mg of MA (niagestin) orally in a cross-over study consisting of 3 periods of 6 weeks. Complete remission was observed in 1 patient, partial remission in 9, no change in 4 and failure in 4 patients. During the 18 weeks of treatment plasma levels of MA gradually increased, irrespective of the dose administered. Significant rises of the basal and TRH-stimulated plasma PRL and basal insulin levels were observed, whereas LH and FSH, estradiol, SHBG and the pituitary-adrenal axis were suppressed. None of these metabolic effects showed a correlation with the clinical response. We concluded that treatment of metastatic breast cancer with 180 mg MA/day is effective and causes minimal adverse effects.


The Journal of Clinical Endocrinology and Metabolism | 2012

The hypercoagulable state in Cushing's disease is associated with increased levels of procoagulant factors and impaired fibrinolysis, but is not reversible after short-term biochemical remission induced by medical therapy.

R. van der Pas; C. de Bruin; F. W. G. Leebeek; M.P.M. de Maat; D. Rijken; Alberto M. Pereira; Johannes A. Romijn; Romana T. Netea-Maier; A.R.M.M. Hermus; Pierre Zelissen; F.H. de Jong; A. J. van der Lely; W. W. de Herder; S. W. J. Lamberts; L. J. Hofland; R. A. Feelders

CONTEXT Cushings disease (CD) is accompanied by an increased risk of venous thromboembolism. Surgery is the primary treatment of CD. OBJECTIVE The aim of the study was to compare hemostatic parameters between patients with CD and controls and to evaluate the effect of medical treatment of CD on hemostasis. DESIGN AND SETTING During 80 d, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline, and ketoconazole, which suppresses adrenocortical steroidogenesis, at four university medical centers in The Netherlands. PATIENTS Seventeen patients with de novo, residual, or recurrent CD were included. MAIN OUTCOME MEASURES We measured urinary free cortisol and parameters of coagulation and fibrinolysis. RESULTS Patients with CD had significantly higher body mass index (P < 0.001), shortened activated partial thromboplastin time (P < 0.01), and higher levels of fibrinogen, Factor VIII, and protein S activity (P < 0.05) compared to healthy control subjects. In addition, fibrinolytic capacity was impaired in patients with CD as reflected by prolonged clot lysis time (P < 0.001) and higher levels of plasminogen activator inhibitor type 1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin (P < 0.01). There were no statistically significant differences in von Willebrand factor:antigen, antithrombin, and protein C activity. After 80 d, 15 of 17 patients had normalized urinary free cortisol excretion. Despite biochemical remission, only slight decreases in antithrombin (P < 0.01) and thrombin-activatable fibrinolysis inhibitor (P < 0.05) levels were observed. Other parameters of coagulation and fibrinolysis did not change significantly. CONCLUSIONS The hypercoagulable state in patients with CD, which is explained by both increased production of procoagulant factors and impaired fibrinolysis, is not reversible upon short-term biochemical remission after successful medical therapy. This may have implications for the duration of anticoagulant prophylaxis in patients with (cured) CD.


Endocrinology | 1993

Activin is produced by rat Sertoli cells in vitro and can act as an autocrine regulator of Sertoli cell function

J.P. de Winter; Hugo Vanderstichele; Marianna A. Timmerman; L. J. Blok; Axel P. N. Themmen; F.H. de Jong

The production of activin by Sertoli cells isolated from 21-day-old rats was studied using the mesoderm-inducing activity of activin on Xenopus laevis animal cap explants, immunoprecipitation and Western blotting. Furthermore, the effects of recombinant bovine activin-A on rat Sertoli cell aromatase activity and FSH and androgen receptor gene expression were examined. Animal cap explants from Xenopus laevis blastulas elongated after culture in conditioned medium of Sertoli cells cultured with or without ovine FSH or conditioned medium of the mouse Sertoli cell-derived TM4 cell line. Animal cap explants cultured in control medium remained spherical. This elongation was also found in the more than 10-kilodalton fraction of the conditioned medium and after heating for 10 min at 95 C, indicating that heat-stable activin-like bioactivity is present in the culture medium. Immunoprecipitation of [35S]methionine-labeled proteins and Western blotting of Sertoli cell-conditioned medium with polyclonal antisera against the inhibition beta-subunits indicated the presence of 24- to 25-kilodalton activin-like immunoreactive material. Sertoli cell aromatase activity was dose-dependently stimulated by ovine FSH after 72 h of culture. Recombinant bovine activin-A partly inhibited this stimulation in a dose-dependent way. This inhibition was also found after 24 h of culture. Furthermore, basal and FSH-stimulated androgen receptor mRNA expression in Sertoli cells and binding of the synthetic androgen R1881 to Sertoli cells were decreased after 24 h of culture in the presence of recombinant bovine activin-A. In the same experiments, FSH receptor mRNA expression was not significantly affected. These results indicate that activin can act as an autocrine regulator of Sertoli cell function.


Molecular and Cellular Endocrinology | 1981

The use of affinity matrices in the purification of inhibin from bovine follicular fluid

E.H.J.M. Jansen; Jacobie Steenbergen; F.H. de Jong; H.J. van der Molen

The protein associated with inhibin-like activity in bovine follicular fluid was purified 80- to 120-fold after successive adsorptions on different affinity matrices, i.e. Matrex gel red A, phenyl sepharose, omega-aminohexyl agarose and concanavalin-A sepharose. Partial characterization of the active protein resulted in the conclusion that inhibin from bovine follicular fluid is a hydrophobic glycoprotein with an apparent molecular weight between 60 000 and 70 000 daltons. An antiserum, raised against an 80-fold purified preparation, prevented the inhibin-like action of bovine follicular fluid on pituitary cells in vitro.


Neuroendocrinology | 2010

Biochemical Predictors of Outcome of Pituitary Surgery for Cushing’s Disease

R A Alwani; W. W. de Herder; M. O. van Aken; J. H. van den Berge; E.J. Delwel; A.H.G. Dallenga; F.H. de Jong; S. W. J. Lamberts; A. J. van der Lely; R. A. Feelders

Objective: Transsphenoidal surgery (TS) is the primary therapy for Cushing’s disease (CD). The aims of this retrospective study were twofold: (i) investigate early and late results of TS for CD, and (ii) evaluate various postoperative tests in order to predict the outcome of TS. Methods: We reviewed the long-term outcome in 79 patients with CD who underwent TS (median follow-up 84 months, range 6–197). Within 2 weeks after surgery, morning serum cortisol concentrations were obtained (n = 78) and corticotropin-releasing hormone (CRH) (n = 53) and metyrapone tests (n = 72) were performed. Three groups of outcome were identified: sustained remission, early failure (persistent CD), and late relapse. Results: Immediate postoperative remission was achieved in 51 patients (65%), whereas 28 patients (35%) had persistent CD after TS. Ten patients developed recurrent CD after initial remission (20%). Morning cortisol: all relapses but one recorded serum cortisol >50 nmol/l. A cortisol threshold value of 200 nmol/l has a positive predictive value of 79% for immediate surgical failure (negative predictive failure [NPV] 97%). CRH test: CRH-stimulated peak cortisol ≧600 nmol/l predicted early failure in 78% (NPV 100%). All relapses recorded CRH-stimulated peak cortisol ≧485 nmol/l. Metyrapone test: 11-deoxycortisol ≧345 nmol/l predicted an early failure in 86% of cases (NPV 94%). Conclusion: Predictive factors of surgical failure are morning cortisol ≧200 nmol/l, 11-deoxycortisol ≧345 nmol/l after metyrapone and CRH-stimulated cortisol ≧600 nmol/l. CRH and/or metyrapone testing are not superior to morning cortisol concentration in the prediction of outcome of TS. Careful long-term follow-up remains necessary independent of the outcome of biochemical testing.

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H.J. van der Molen

Erasmus University Rotterdam

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G.J. van Steenbrugge

Erasmus University Rotterdam

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Fritz H. Schröder

Erasmus University Rotterdam

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W.M. van Weerden

Erasmus University Rotterdam

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F. F. G. Rommerts

Erasmus University Rotterdam

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J.G.M. Klijn

Erasmus University Rotterdam

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W. J. De Greef

Erasmus University Rotterdam

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A. Van Kreuningen

Erasmus University Rotterdam

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Axel P. N. Themmen

Erasmus University Rotterdam

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