Dietrich Klingmüller

Inhibition of human cytochrome P450 aromatase activity by butyltins

Organotin compounds are widely used as antifouling agents and bioaccumulate in the food chain. Tributyltin chloride (TBT) has been shown to induce imposex in female gastropods. On the basis of this observation it has been suggested that TBT acts as an endocrine disrupter inhibiting the conversion of androgens to estrogens mediated by the aromatase cytochrome P450 enzyme. However, to date, the molecular basis of TBT-induced imposex and in particular its putative inhibitory effects on human aromatase cytochrome P450 activity have not been investigated. Therefore, we examined the effects of the organotin compounds tetrabutyltin (TTBT), TBT, dibutyltin dichloride (DBT) and monobutyltin trichloride (MBT) on human placental aromatase activity. TBT was found to be a partial competitive inhibitor of aromatase activity with an IC(50) value of 6.2 microM with 0.1 microM androstenedione as substrate. TBT impaired the affinity of the aromatase to androstenedione but did not affect electron transfer from NADPH to aromatase via inhibiting the NADPH reductase. DBT acted as a partial but less potent inhibitor of human aromatase activity (65% residual activity), whereas TTBT and MBT had no effect. The residual activity of TBT-saturated aromatase was 37%. In contrast, human 3beta-HSD type I activity was only moderately inhibited by TBT (80% residual activity). Moreover, neither TTBT or DBT nor MBT inhibited the 3beta-HSD type I activity. Together, these results suggest that the environmental pollutants TBT and DBT, both present in marine organisms, textile and plastic products, may have specific impacts on the metabolism of sex hormones in humans.

Polycystic ovary syndrome in patients with focal epilepsy: a study in 93 women

A prospective cohort analysis of premenopausal women with focal epilepsy was conducted in order to determine whether polycystic ovary syndrome (PCOS) is a common finding in women treated with antiepileptic drugs (AED). This study was carried out in 93 of 150 women (aged between 20 and 53 years; mean, 34.3 years) with chronic focal epilepsy consecutively cared for at the Department of Epileptology, University of Bonn: 38 were receiving one AED (18 valproate, 20 carbamazepine), 36 more than one drug, and 19 were without medication. Patients were followed-up for 6 months. PCOS was defined as hyperandrogenism (testosterone concentration, > 0.7 ng/ml) combined with oligomenorrhoea (cycle length, > 35 days) or amenorrhoea. PCOS was identified in two out of 19 (10.5%) patients receiving no medication; in four of 38 (10.5%) of patients receiving monotherapy, and in none of the patients receiving more than one AED. The incidence of PCOS in patients treated with valproate monotherapy (11.1%) was similar to that in patients treated with carbamazepine (10%) and also to that in patients not treated with AEDs. The results of this study suggest that the manifestation of PCOS in women with focal epilepsy is not related to the administration of valproate or carbamazepine.

The hypothalamic-pituitary-adrenal axis of patients with severe sepsis: altered response to corticotropin-releasing hormone.

ObjectiveTo investigate the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with severe sepsis by stimulating with corticotropin-releasing hormone (CRH). DesignProspective observational study in consecutive intensive care unit patients with severe sepsis. SettingSurgical intensive care unit and outpatient department of endocrinology in a university hospital. PatientsThe study included 20 patients with the diagnosis of severe sepsis; six critically ill, nonseptic patients after major surgery; ten patients with primary adrenal insufficiency; ten patients with anterior pituitary insufficiency; and ten individuals without clinical signs of HPA axis disturbance. InterventionsCRH tests were performed with an intravenous bolus injection of 100 &mgr;g of human CRH. Measurements and Main Results We studied the functional integrity of the HPA axis in patients with severe sepsis by performing the CRH test. In addition, during the period of severe sepsis, we repeatedly measured basal plasma concentrations of adrenocorticotropin hormone (ACTH) and cortisol. The mean basal plasma cortisol concentration was decreased significantly in nonsurvivors with severe sepsis (288.8 ± 29.1 [sem] nmol/L) compared with survivors (468.1± 18.6 nmol/L;p < .01). By calculating the ACTH/cortisol indices, we found no evidence for adrenal insufficiency in patients with severe sepsis. The mean ACTH/cortisol indices of nonsurvivors with severe sepsis (0.02 ± 0.008) and survivors (0.01 ± 0.002) were significantly lower compared with the index of patients with primary adrenal insufficiency (6.8 ± 1.0;p < .001). In contrast, in nonsurvivors with severe sepsis, the plasma cortisol response to CRH stimulation was impaired compared with survivors: The mean basal cortisol concentration within the CRH test was 269.4 ± 39.8 nmol/L in nonsurvivors compared with 470.8 ± 48.4 nmol/L in survivors and increased to a peak value of 421.6 ± 72.6 nmol/L in nonsurvivors and 680.7 ± 43.8 nmol/L in survivors (p < .02). However, the change in plasma cortisol, expressed as mean ± sem and calculated by subtracting the basal cortisol from the peak cortisol after CRH stimulation, was not significantly different in survivors with severe sepsis (243.5 ± 36.1, range 111.0–524.0 nmol/L, n = 15) compared with nonsurvivors (161.0 ± 38.9, range 42.0–245.0 nmol/L, n = 5;p > .05). ConclusionsWe found lower basal plasma cortisol concentrations in nonsurvivors compared with survivors of severe sepsis. In addition, the plasma cortisol response to a single CRH stimulation was impaired in nonsurvivors compared with survivors. Reduced responses to CRH stimulation may reflect a state of endocrinologic organ dysfunction in severe sepsis.

Serum Sex Hormones Are Altered in Patients with Chronic Temporal Lobe Epilepsy Receiving Anticonvulsant Medication

Summary: Purpose: To evaluate the changes in serum sex hormones of gonadal or adrenal origin, the gonadotropic hormones, and sex hormone‐binding globulin (SHBG) in men and women with chronic temporal lobe epilepsy (TLE), who are undergoing monotherapy with carbamazepine or receiving carbamazepine in combination with other anticonvulsant drugs.

Expression of CYP19 (aromatase) mRNA in different areas of the human brain.

The conversion of androgens to estrogens by CYP19 (cytochrome P450AROM, aromatase) is an important step in the mechanism of androgen action in the brain. CYP19 expression has been demonstrated in the brain of various animal species and in the human temporal lobe. Studies on postnatal CYP19 expression in various other areas of the human brain are rare and carried out in a limited number of post mortem obtained tissue. Therefore, we investigated CYP19 mRNA expression in fresh human frontal and hippocampal tissues and compared them to the expression in temporal neocortex tissues. We studied biopsy materials removed at neurosurgery from 45 women and 54 men with epilepsy. Quantification of CYP19 mRNA was achieved by nested competitive reverse transcription-PCR. CYP19 mRNA concentrations were significantly higher in temporal (2.29+/-0.40 arbitrary units, AU, mean +/- SEM; n = 57) than in frontal neocortex specimens (0.92+/-0.17 AU; n = 18; P<0.04). In hippocampal tissue specimens CYP19 expression (1.41+/-0.18 AU; n = 24) was lower than in temporal neocortex specimens, but the difference did not reach statistical significance. Sex differences were not observed in any of the brain regions under investigation. In conclusion, CYP19 mRNA is expressed in the human temporal and frontal neocortex as well as in the hippocampus. Regardless of sex, CYP19 expression was significantly higher in the temporal than in the frontal neocortex.

Digoxin-like natriuretic activity in the urine of salt loaded healthy subjects

SummaryIn previous studies we have demonstrated a natriuretic factor of small molecular weight (<1,000 Daltons) in the serum and urine of salt loaded subjects. This factor isolated from salt loaded animals inhibits the Na-K-ATPase enzyme system. In addition, the natriuretic material isolated from plasma of salt-loaded dogs was shown to bind to specific digoxin antibodies. It was therefore suggested that a digitalis-like endogenous natriuretic factor (endoxin) is released in response to saline loading. In the present study we therefore investigated the presence of such an endogenous natriuretic digitalis-like activity in the urine of healthy volunteers during high salt intake. Using Sephadex G-25 for chromatographic separation of urine a material elutes as a single peak in the natriuretic post-salt fraction IV which is specifically bound to digoxin antiserum complex. Mean peak activity amounted to 1.55±0.48 ng/ml digoxin equivalents. We further purified the natriuretic material by immunoprecipitation with the digoxin antiserum complex. This purification procedure resulted in a more than 10-fold increase in specific natriuretic activity from 2.7±0.4 to 30.4±5.8 µEq Na+·min−1·mg−1. Thus the digitalis-like natriuretic activity previously observed in the plasma of saline loaded dogs is also present in the urine of healthy subjects during high dietary salt intake. Immunoprecipitation may offer a meaningfull tool for further isolation and identification of the natriuretic hormone(s).ZusammenfassungIn früheren Untersuchungen haben wir einen kleinmolekularen (<1000 Dalton) natriuretischen Faktor in Serum und Urin von Kochsalz-belasteten, gesunden Versuchspersonen nachgewiesen. Dieser Faktor hemmt das Na-K-ATPase Enzymsystem. Kürzlich wurde gezeigt, daß eine natriuretische Aktivität, isoliert aus dem Plasma Kochsalz-belasteter Hunde, spezifisch von Digoxin-Antikörpern gebunden wird. Es wurde daher postuliert, daß Kochsalzbelastung die Freisetzung eines Digitalis-ähnlichen endogenen natriuretischen Faktors (Endoxin) stimuliert. Wir untersuchten daher in der vorliegenden Arbeit die Existenz eines solchen Digoxin-ähnlichen Faktors im Urin gesunder, Kochsalz-belasteter Probanden. Der Urin wurde an Sephadex G-25 chromatographiert. Dabei eluierte in der natriuretischen Fraktion IV ein Material, das von einem Digoxin-Antiserum-Komplex gebunden wird, in einem einzigen Gipfel. Die maximale Aktivität in Fraktion IV betrug 1,55±0,48 ng/ml Digoxin-Äquivalente. Durch Reinigung des natriuretischen Materials mittels Immunpräzipitation mit dem Digoxin-Antiserum-Komplex wurde eine mehr als 10fache Steigerung der spezifischen natriuretischen Aktivität im Mittel von 2,7±0,4 auf 30,4±5,8 µÄq Na+ min−1·mg−1 erreicht. Die zunächst im Plasma Kochsalz-belasteter Hunde beobachtete Digitalis-ähnliche natriuretische Aktivität ist somit auch im Urin gesunder Kochsalz-belasteter Probanden nachweisbar. Immunpräzipitation könnte ein hilfreicher Schritt bei der Isolierung des natriuretischen Hormons sein.

Testicular function after radioiodine therapy for thyroid carcinoma

Abstract.Radiotherapy can cause infertility in both men and women. However, few data are available concerning the effects of radioiodine therapy for thyroid carcinoma on testicular function. We investigated 25 men (age 23–73 years) with differentiated thyroid carcinoma in a longitudinal prospective trial. Follicle-stimulating hormone (FSH), inhibin B, luteinising hormone (LH) and testosterone were measured before (n=25) and 3 months (n=11), 6 months (n=18), 12 months (n=22), and 18 months (n=18) after radioiodine therapy [radioiodine dose (mean ± SEM): 9.8±0.89 GBq]. Before therapy, FSH was 5.4±0.77 IU/l; it increased significantly (P<0.001) to 21.3±2.4 IU/l after 6 months and fell to 7.4±1.3 IU/l after 18 months (normal range: 1.8– 9.2 IU/l). Inhibin B was significantly decreased (P<0.001) from 178±25.3 pg/ml before therapy to 22.2±5.5 pg/ml after 3 and 29.4±5.7 pg/ml after 6 months and rose to 154±23.3 pg/ml after 18 months (normal range 75– 350 pg/ml). LH and testosterone were within the normal range during the whole study (1.6–9.2 IU/l and 10.4–34.7 nmol/l, respectively). LH was significantly increased (P<0.001) from 2.8±0.33 IU/l before therapy to 5.9±0.69 IU/l 6 months after therapy and then fell slowly to 4.0±0.45 IU/l after 18 months. Total testosterone was significantly increased (P<0.01) from 12.8±0.99 nmol/l at baseline to 19.8±1.7 nmol/l after 12 months and 19.6±1.7 nmol/l after 18 months. The testosterone/LH ratio (normal range: 3.3–17.9 nmol/IU) fell from 5.8±0.66 nmol/IU to 3.0±0.36 nmol/IU after 3 months (P<0.01); it remained close to the latter value after 6 months (3.4±0.49 nmol/IU) and then rose to 5.5± 0.6 nmol/IU after 18 months. In conclusion, 3 and 6 months after radioiodine therapy all patients showed elevated FSH and decreased inhibin B levels, reflecting severely impaired spermatogenesis. At the same time a compensated insufficiency of the Leydig cell function was observed. Eighteen months after the last radioiodine therapy, mean values of gonadal function had completely recovered.

Does Octreotide Treatment Improve the Surgical Results of Macro-Adenomas in Acromegaly? A Randomized Study

Summary It is not clear whether the pre-operative treatment of GH-secreting pituitary adenomas with Octreotide improves the surgical remission rates of acromegaly. In a prospective controlled study the results of transsphenoidal surgery in newly diagnosed GH-secreting macro-adenomas were compared in patients with (n=11, group A) and without (n=13, group B) preoperative Octreotide treatment. During the treatment with a daily dosage of 470±160 μg Octreotide for 16, 5±10 weeks, the GH- and IGF-1-values of group A dropped significantly from 38, 9±34, 1 to 6, 8±4, 9 μg/l and from 2, 7±1 to 1, 7±0, 7 arbitrary units respectively. The adenoma-shrinkage from 5, 9±5, 8 to 4, 7±4, 9 cm3 missed statistical significance by little. There was no statistically significant difference between the postoperative acromegaly remission rates of 55% in group A and 69% in group B. Of the adenomas that postoperatively were not in remission, 80% in group A and 75% in group B disclosed an infiltrative growth pattern not influenced by the Octreotide pretreatment. All other patients not cured presented with initial GH-values of >50μ{\rm g/l}. There was no statistically significant difference between the postoperative anterior pituitary function in the two patient groups. In this study Octreotide was not beneficial in improving the results of GH-secreting pituitary macro-adenoma surgery. However, larger prospective controlled studies are needed to address this issue.

Modeling a negative response bias in the human amygdala by noradrenergic-glucocorticoid interactions.

An emerging theme in the neuroscience of emotion is the question of how acute stress shapes, and distorts, social-emotional behavior. The prevailing neurocircuitry models of social-emotional behavior emphasize the central role of the amygdala. Acute stress leads to increased central levels of norepinephrine (NE) and cortisol (CORT), and evidence suggests that these endogenous neuromodulators synergistically influence amygdala responses to social-emotional stimuli. We therefore hypothesized that amygdala responses to emotional facial expressions would be susceptible to pharmacologically induced increases in central NE and CORT levels. To specifically test this hypothesis, we measured amygdala activation to emotional faces using functional magnetic resonance imaging in 62 healthy subjects under four pharmacological conditions: (1) single oral dose of placebo, (2) 4 mg of the selective NE-reuptake inhibitor reboxetine (RBX), (3) 30 mg of hydrocortisone, or (4) both drugs in combination. We found that a decrease in amygdala activation to positive facial emotion was coupled with an increase in amygdala activation to negative facial emotion in the RBX-CORT combined challenge condition. In conclusion, a pharmacologically induced elevation of central NE and CORT levels in healthy subjects created a negative response bias in the amygdala that did not exist at baseline. Our results implicate a causative role of NE–CORT interactions in the emergence of a negative bias of cognitive and emotional functions which is germane in stress-related affective spectrum disorders.

Incidence, clinical manifestations, and course of water and electrolyte metabolism disturbances following transsphenoidal pituitary adenoma surgery: a prospective observational study.

OBJECT The authors prospectively studied the incidence, spectrum of clinical manifestations, course, and risk factors of water and electrolyte disturbances (WEDs) following transsphenoidal pituitary adenoma surgery. METHODS From the preoperative day to the 14th postoperative day, 57 successive patients undergoing transsphenoidal adenomectomy were monitored daily for body weight, balance of fluids, serum electrolytes, plasma osmolality, plasma antidiuretic hormone (ADH) levels, urinary sodium excretion, urinary osmolality, and subjective sensation of thirst. The type of adenoma operated on and the intraoperative manipulation of the neurohypophysis were also recorded. RESULTS Fifty-seven patients (mean age 55 years, 61.4% females) harbored 30 clinically hormone-inactive and 27 hormone-secreting pituitary adenomas. Postoperative WED occurred in 75.4% of the patients: in 38.5% as isolated diabetes insipidus (DI); in 21% as isolated hyponatremia; and in 15.7% as combined DI-hyponatremia. The maximum of medians of diuresis (5.750 L) in patients with isolated DI occurred on postoperative Day 2. Nadir of medians of hyponatremia (132 mmol/L) in patients with isolated hyponatremia occurred on postoperative Day 9. In patients with combined DI-hyponatremia, maximum of medians of diuresis (5.775 L) occurred on the 2nd day and nadir of medians of hyponatremia (130 mmol/L) on the 10th postoperative day. Altogether, 8.7% of the patients had to be treated with desmopressin because of DI persisting for >3 months. Of all the patients with hyponatremia, 42.8% were treated by transient fluid-intake restriction due to an IH of <130 mmol/L with or without clinical symptomatology. Transient acute renal failure occurred in one of these patients. Generally, the occurrence of postoperative WEDs was linked to the intraoperative manipulation of the neurohypophysis. Increased thirst correlated significantly with DI (p=0.001 and 0.02, respectively) and decreased thirst with the hyponatremic episode in patients with combined DI-hyponatremia (p=0.003). Decreased urine osmolality correlated significantly with the presence of DI (p=0.023). Electrolyte-free water clearance and urinary Na+ excretion were not correlated with DI and hyponatremia. Antidiuretic hormone was not suppressed during hyponatremia. CONCLUSIONS Water and electrolyte disturbances occurred in the majority of patients undergoing transsphenoidal adenomectomy and were usually transient. Diabetes insipidus is more frequent than hyponatremia. Diabetes insipidus usually occurs during the 1st postoperative day and resolves in the majority of cases within 10 days. In few patients, DI may persist and require therapy with ADH analogs. Hyponatremia usually occurs at the end of the 1st postoperative week and resolves in most cases within 5 days. Very few patients will need treatment other than fluid-intake restriction to avoid serious complications. Thus, careful monitoring of the WEDs in patients undergoing transsphenoidal pituitary adenoma surgery is mandatory for the first 10 postoperative days.