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S Palacio and R Felix

BACKGROUND: Colony-stimulating factor-1 (CSF-1), a growth and survival factor for osteoclasts, stimulates these cells to spread and migrate towards a gradient of CSF-1. This may support the translocation of osteoclasts to new sites on the bone surface to be resorbed. Phosphoinositide 3-kinase (PI 3-K) is a lipid kinase participating in various signal transduction pathways. OBJECTIVE: To investigate the role of PI 3-K in the CSF-1-induced spreading of osteoclasts. METHODS: In isolated rat osteoclasts treated with or without CSF-1, the distribution of PI 3-K and proteins phosphorylated on tyrosine were investigated using immunofluorescence. In murine osteoclast-like cells grown from bone marrow cells co-cultured with osteoblasts, the activation of the PI 3-K by CSF-1 was determined both in vivo and in vitro. In vivo, the enzyme product in the cell was determined after extraction and separation with thin layer chromatography; in vitro, PI 3-K activity was measured in the pellet immunoprecipitated from the cell lysate. RESULTS: Inhibition of PI 3-K blocked the CSF-1-induced spreading of osteoclasts. In spreading osteoclasts, a portion of PI 3-K was translocated to the periphery where proteins phosphorylated on tyrosine appeared simultaneously. In osteoclast-like cells, CSF-1 stimulated PI 3-K activity. This activity could be immunoprecipitated with antibody against phophotyrosine residues. CONCLUSION: PI 3-K participates in the CSF-1-induced spreading of osteoclasts. The activated PI 3-K may induce the reorganization of the cytoskeleton resulting in spreading and migration.

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Cipriano Garcia del Rio, María Rosario R Moreno, Antonio Osuna, Juan de Dios Luna, Joaquín García-Estañ and Félix Vargas

Abstract

Objective: We evaluated the influence of chronic blockade of the renin-angiotensin system on hypertension induced by long-term thyroxine (T4) administration. To this end, we determined the effects of chronic treatment with captopril on blood pressure, cardiac hypertrophy and other renal and metabolic variables of hypertensive hyperthyroid rats.

Methods: T4 was administered s.c. at 0·38 μmol/kg per day and captopril was given in the drinking water (1·38 mmol/l). Both treatments were maintained for 6 weeks. Control rats received tap water. After the treatment period, the rats were placed in metabolic cages. Later, blood pressure was measured in conscious rats by intra-arterial determination.

Results: T4-treated rats showed an increased mean arterial pressure (MAP) whereas, in rats treated with T4 plus captopril, MAP was similar to that of the control group. Captopril did not affect the increased heart rate or ventricular weight/body weight ratio of hyperthyroid rats, but it improved the reduced creatinine clearance of these animals.

Conclusions: The elevation in blood pressure produced by long-term T4 administration was prevented by chronic blockade of the renin-angiotensin system. Captopril improved the renal function of hyperthyroid rats, but did not affect the relative cardiac hypertrophy of these animals.

European Journal of Endocrinology 136 656–660

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Adrian T Billeter, Javier R de la Garza Herrera, Katharina M Scheurlen, Felix Nickel, Franck Billmann and Beat P Müller-Stich

Obesity and its associated comorbidities have become one of the largest challenges for health care in the near future. Conservative therapy for obesity and related comorbidities has a very high failure rate and poor long-term results. Similarly, the conservative and medical management of the majority of metabolic diseases such as type 2 diabetes mellitus are only able to slow down disease progression but have no causal effect on the disease process. Obesity surgery has evolved as a highly effective therapy for severe obesity achieving long-lasting weight loss. Furthermore, several studies have demonstrated the beneficial effects of obesity surgery on reduction of overall mortality, reduction of cardiovascular events and superior control of obesity-related diseases such as type 2 diabetes mellitus, dyslipidemia and also the non-alcoholic steatohepatitis compared to medical therapy. Based on these findings, the term ‘metabolic surgery’ with the focus on treating metabolic diseases independent of body weight has been coined. Of great interest are recent studies that show that even existing complications of metabolic diseases such as diabetic nephropathy or the non-alcoholic steatohepatitis can be reversed by metabolic surgery. Although metabolic surgery has proven to be a safe and effective treatment for obesity, resolution of comorbidities and enhancing quality of life, it is still uncertain and unclear, which surgical procedure is the most effective to achieve these metabolic effects. The aim of this review is to compare the effects of the two currently most widely used metabolic operations, the Roux-en-Y gastric bypass and the sleeve gastrectomy in the treatment of obesity and its related comorbidities.

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A Hannemann, M Bidlingmaier, N Friedrich, J Manolopoulou, A Spyroglou, H Völzke, F Beuschlein, J Seissler, R Rettig, S B Felix, R Biffar, A Döring, C Meisinger, A Peters, H E Wichmann, M Nauck, H Wallaschofski and M Reincke

Objective

The prevalence of primary aldosteronism in unselected hypertensive patients is currently unknown. We investigated the frequency of positive screening results for primary aldosteronism based on the aldosterone-to-renin ratio (ARR) in hypertensive subjects aged 30–79 years from two German epidemiological studies. We further examined the frequency of positive screening results in subjects with resistant hypertension or stage III hypertension and assessed possible disparities between untreated and treated hypertensive subjects.

Methods

Data were obtained from the first follow-ups of the population-based Study of Health in Pomerania (SHIP; n=1392) and the Cooperative Health Research in the Region of Augsburg (KORA; n=1052). Study-specific reference ranges for plasma aldosterone concentration (PAC), plasma renin concentration (PRC) and the ARR were applied. Confirmation tests for primary aldosteronism were not performed in these epidemiological studies. Three definitions for a positive screening for primary aldosteronism were applied: A) increased ARR; B) increased ARR and decreased PRC; and C) increased ARR and increased PAC and decreased PRC.

Results

The frequency of positive screening results was 7.0, 3.8 and 0.2% according to definitions A–C respectively. In the subgroups of subjects with resistant hypertension (11.9, 5.5 and 0.9%) or stage III hypertension (18.3, 14.0 and 1.1%), these frequencies were markedly higher than those in the general hypertensive population. There was no difference in the frequency of positive screening results between the treated and untreated hypertensive subjects.

Conclusions

A maximum of 7.0% of the hypertensive population in Germany shows a positive screening result for primary aldosteronism. Thus, primary aldosteronism may be less frequent than previously expected based on data from referred hypertensive patients.

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Mariko Sue, Victoria Martucci, Florina Frey, Jacques W M Lenders, Henri J Timmers, Mariola Pęczkowska, Aleksander Prejbisz, Brede Swantje, Stefan R Bornstein, Wiebke Arlt, Martin Fassnacht, Felix Beuschlein, Mercedes Robledo, Karel Pacak and Graeme Eisenhofer

Objective

Testing for succinate dehydrogenase subunit B (SDHB) mutations is recommended in all patients with metastatic phaeochromocytomas and paragangliomas (PPGLs), but may not be required when metastatic disease is accompanied by adrenaline production. This retrospective cohort study aimed to establish the prevalence of SDHB mutations among patients with metastatic PPGLs, characterised by production of adrenaline compared with those without production of adrenaline, and to establish genotype–phenotype features of metastatic PPGLs according to underlying gene mutations.

Design and methods

Presence of SDHB mutations or deletions was tested in 205 patients (114 males) aged 42±16 years (range 9–86 years) at diagnosis of metastatic PPGLs with and without adrenaline production.

Results

Twenty-three of the 205 patients (11%) with metastatic PPGLs had disease characterised by production of adrenaline, as defined by increased plasma concentrations of metanephrine larger than 5% of the combined increase in both normetanephrine and metanephrine. None of these 23 patients had SDHB mutations. Of the other 182 patients with no tumoural adrenaline production, 51% had SDHB mutations. Metastases in bone were 36–41% more prevalent among patients with SDHB mutations or extra-adrenal primary tumours than those without mutations or with adrenal primary tumours. Liver metastases were 81% more prevalent among patients with adrenal than extra-adrenal primary tumours.

Conclusion

SDHB mutation testing has no utility among patients with adrenaline-producing metastatic PPGLs, but is indicated in other patients with metastatic disease. Our study also reveals novel associations of metastatic spread with primary tumour location and presence of SDHB mutations.

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Christina M Berr, Mareike R Stieg, Timo Deutschbein, Marcus Quinkler, Ralf Schmidmaier, Andrea Osswald, Nicole Reisch, Katrin Ritzel, Christina Dimopoulou, Julia Fazel, Stefanie Hahner, Günter K Stalla, Felix Beuschlein and Martin Reincke

Background

Cushing’s syndrome (CS) is characterized by an excessive secretion of glucocorticoids that results in a characteristic clinical phenotype. One feature of clinical hypercortisolism is breakdown of protein metabolism translating into clinical consequences including glucocorticoid-induced myopathy. While surgery is effective in control of cortisol excess, the effect of biochemical remission on muscular function is yet unclear.

Methods

In a cross-sectional study we analyzed 47 patients with CS during the florid phase (ActiveCS). 149 additional patients were studied 2–53 years (mean: 13 years) after surgery in biochemical long-term remission (RemissionCS). Also, 93 rule-out CS patients were used as controls (CON). All subjects were assessed for grip strength using a hand grip dynamometer and underwent the chair rising test (CRT).

Results

Hand grip strength (85% vs 97% of norm, P = 0.002) and the CRT performance (9.5 s vs 7.1 s, P = 0.001) were significantly lower in ActiveCS compared to the CON group. Six months after treatment grip strength further decreased in CS (P = 0.002) and CRT performance remained impaired. The RemissionCS group (mean follow-up 13 years) had reduced hand grip strength (92% compared to normal reference values for dominant hand, P < 0.001). The chair rising test performance was at 9.0 s and not significantly different from the ActiveCS group (P = 0.45).

Conclusion

CS affects muscle strength in the acute phase, but functional impairment remains detectable also during long-term follow-up despite biochemical remission.

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Luis G Pérez-Rivas, Marily Theodoropoulou, Troy H Puar, Julia Fazel, Mareike R Stieg, Francesco Ferraù, Guillaume Assié, Monica R Gadelha, Timo Deutschbein, Maria C Fragoso, Benno Kusters, Wolfgang Saeger, Jürgen Honegger, Michael Buchfelder, Márta Korbonits, Jérôme Bertherat, Günter K Stalla, Ad R Hermus, Felix Beuschlein and Martin Reincke

Objective

Somatic mutations in the ubiquitin-specific protease 8 (USP8) gene are frequent in corticotroph tumors causing Cushing’s disease (CD). Corticotroph tumor progression, the so-called Nelson’s syndrome (NS), is a potentially life-threatening complication of bilateral adrenalectomy in patients with refractory CD that is caused by the development of an ACTH-secreting tumor of the pituitary gland. Whether USP8 alterations are also present in progressive Nelson’s tumors has not been studied in detail so far.

Design and Methods

Retrospective, multicenter study involving tumors from 33 patients with progressive corticotroph tumors (29 females) and screening for somatic mutations on the mutational hotspot of the USP8 gene in the exon 14 with Sanger sequencing.

Results

Fifteen out of 33 tumors (45%) presented with a mutation in the exon 14 of USP8, with c.2159C>A (p.Pro720Gln) being the most frequent (9/33), followed by c.2155_2157delTCC (p.Ser718del, 4/33) and c.2152T>C (p.Ser718Pro, 2/33). This prevalence is similar to that previously reported for CD. Mutations were found exclusively in females. Other variables, such as age at diagnosis with NS, body mass index, hyperpigmentation, visual field defects, adenoma size or mortality, did not significantly differ between patients with wild-type and mutant tumors. Patients with USP8 mutant tumors exhibited higher levels of plasma ACTH after surgery (median: 640 vs 112 pg/mL, P = 0.03). No differences were observed in ACTH normalization (<50 pg/mL) and tumor control after surgery for Nelson’s tumor.

Conclusion

Somatic mutations in USP8 are common in Nelson’s tumors, indicating that they do not drive the corticotroph tumor progression that leads to NS, and may be associated with a less favorable biochemical outcome after surgery for Nelson’s tumor.