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Publications (12)60.91 Total impact

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    ABSTRACT: p8 protein expression is known to be upregulated in the exocrine pancreas during acute pancreatitis. Own previous work revealed glucose-dependent p8 expression also in endocrine pancreatic beta-cells. Here we demonstrate that glucose-induced INS-1 beta-cell expansion is preceded by p8 protein expression. Moreover, isopropylthiogalactoside (IPTG)-induced p8 overexpression in INS-1 beta-cells (p8-INS-1) enhances cell proliferation and expansion in the presence of glucose only. Although beta-cell-related gene expression (PDX-1, proinsulin I, GLUT2, glucokinase, amylin) and function (insulin content and secretion) are slightly reduced during p8 overexpression, removal of IPTG reverses beta-cell function within 24 h to normal levels. In addition, insulin secretion of p8-INS-1 beta-cells in response to 0-25 mM glucose is not altered by preceding p8-induced beta-cell expansion. Adenovirally transduced p8 overexpression in primary human pancreatic islets increases proliferation, expansion, and cumulative insulin secretion in vitro. Transplantation of mock-transduced control islets under the kidney capsule of immunosuppressed streptozotocin-diabetic mice reduces blood glucose and increases human C-peptide serum concentrations to stable levels after 3 days. In contrast, transplantation of equal numbers of p8-transduced islets results in a continuous decrease of blood glucose and increase of human C-peptide beyond 3 days, indicating p8-induced expansion of transplanted human beta-cells in vivo. This is underlined by a doubling of insulin content in kidneys containing p8-transduced islet grafts explanted on day 9. These results establish p8 as a novel molecular mediator of glucose-induced pancreatic beta-cell expansion in vitro and in vivo and support the notion of existing beta-cell replication in the adult organism.
    AJP Endocrinology and Metabolism 01/2007; 291(6):E1168-76. · 4.51 Impact Factor
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    ABSTRACT: The present study evaluated the evolution of cardiac morphology, function, and late enhancement as a noninvasive marker of myocardial fibrosis, and their inter-relation during enzyme replacement therapy in patients with Fabry's disease using magnetic resonance imaging and color Doppler myocardial imaging. Late enhancement, which was present in up to 50% of patients, was associated with increased left ventricular mass, the failure of a significant regression of hypertrophy during enzyme replacement therapy, and worse segmental myocardial function. Late enhancement may predict the effect of enzyme replacement therapy on left ventricular mass and cardiac function.
    The American Journal of Cardiology 06/2006; 97(10):1515-8. · 3.21 Impact Factor
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    ABSTRACT: Enzyme replacement therapy (ERT) with recombinant human alpha-galactosidase A (r-halphaGalA) enhances microvascular globotriaosylceramide clearance and improves clinical symptoms in patients with Fabry disease. We evaluated whether these effects are translated into a long-term benefit of kidney and heart function. We did a single center, prospective, open label study in 26 patients with Fabry disease (one early death, follow-up in 25 patients). r-Alpha-GalA was administered in a dosage of 1 mg/kg body weight every second week. The effect of therapy on clinical end points (death, cardiac and cerebrovascular event, renal failure), cardiac and renal function monitored by Doppler echocardiography, 99Tc-GFR, and proteinuria was investigated. After a mean treatment time of 23 +/- 8 months, nine patients experienced 12 end points, including two deaths. All end points occurred in patients with impaired renal function (n = 16; GFR 71 +/- 17 ml/min/1.73 m2). Despite ERT, renal function deteriorated to 60 +/- 23 ml/min/1.73 m2 (P = 0.04) and left ventricular posterior wall thickness (PWT) did not change (14.0 +/- 2.1 vs 13.4 +/- 2.3 mm). In contrast, patients without impairment of renal function (n = 9) had a more favorable outcome (no clinical events; GFR 115 +/- 18 vs 102 +/- 14 ml/min/1.73 m2, NS; PWT 11.7 +/- 1 and 10.7+/-0.7 mm, P = 0.04). Proteinuria remained unchanged (1.34 +/- 0.94 vs 1.01 +/- 0.97 g/day, n = 10). Patients with impaired renal function have a less favorable outcome and may develop cardiovascular and renal end points despite ERT.
    Kidney International 05/2006; 69(7):1216-21. · 8.52 Impact Factor
  • European Journal of Pediatrics 04/2006; 165(3):205-6. · 1.91 Impact Factor
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    ABSTRACT: Fabry Disease is an X-linked lysosomal storage disorder leading to the accumulation of glycosphingolipids, mainly globotriaosylceramides in all tissues and solid organs of the body. The disease was described by Johannes Fabry and William Anderson coevally in 1898. Beside the involvement of the central nervous system, peripheral nerves, kidneys, skin and endovascular endothelium, the heart plays a major role in the disease. Left ventricular hypertrophy is one hallmark initially presenting with preserved ventricular function. However, with progression of the disease patients die due to heart failure. Though angina is often reported, the incidence of epicardial coronary stenosis is not a dominant feature, if at all small vessel disease can occur. In respect of arrhythmias a broad spectrum can be seen including shortened or prolonged PR-intervals, AV blocks of different degrees and sometimes malignant ventricular arrhythmias. In the past, women were considered to be carriers of the disease but hardly to develop clinical symptoms. In recent years there is evidence that female carriers may more often be affected with severe symptoms. In addition, a group of Fabry patients displaying mainly cardiac involvement were described as having a cardiac variant of the disease. This implied the hypothesis that some of those patients with unexplained myocardial hypertrophy do suffer from Fabry disease. Since 2002 enzyme replacement therapy is available and there is first evidence for its efficacy to reduce hypertrophy and increase myocardial function. If this is associated with a prognostic improvement has to be determined in future studies.
    Zeitschrift für Kardiologie 10/2005; 94(9):557-63. · 0.97 Impact Factor
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    ABSTRACT: The aim of this clinical cross-sectional study was to investigate the cardiac interrelation of morphological and functional abnormalities in patients with Fabry disease. Fifty-one patients (5-78 years) were compared with 25 controls (8-77 years). In all subjects, end-diastolic thickness of the left ventricle was measured by echocardiography and ultrasonic peak systolic strain rate (SR) was extracted to assess regional myocardial function. Magnetic resonance imaging was performed to assess late-enhancement for the detection of myocardial fibrosis in Fabry patients (n=39). In patients, women <20 years of age had no hypertrophy, no late-enhancement, and normal radial and longitudinal function (SR longitudinal=-1.7+/-0.5 s(-1); P=n.s. compared with controls). Ten women, >20 years of age, had no hypertrophy, no late-enhancement, normal radial and longitudinal function in the septal wall, but reduced longitudinal function in the lateral wall (SR=-1.4+/-0.5 s(-1)). All male patients without hypertrophy and no late-enhancement had normal radial function but reduced longitudinal function in both the septal and lateral walls (SR=-1.3+/-0.3 s(-1)). Patients with hypertrophy but without late-enhancement (n=13) had reduced radial and longitudinal function. Twelve patients displaying hypertrophy and late-enhancement had severely reduced radial and longitudinal function (SR=-1.1+/-0.5 s(-1)). Two of them with the worst impairment of regional function (SR=-0.8+/-0.6 s(-1)) died in the follow-up period. These results illustrate the variation of morphological changes and its functional consequences in Fabry cardiomyopathy.
    European Heart Journal 06/2005; 26(12):1221-7. · 14.72 Impact Factor
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    ABSTRACT: AIMS: The aim of this clinical cross-sectional study was to investigate the cardiac interrelation of morphological and functional abnormalities in patients with Fabry disease. METHODS AND RESULTS: Fifty-one patients (5-78 years) were compared with 25 controls (8-77 years). In all subjects, end-diastolic thickness of the left ventricle was measured by echocardiography and ultrasonic peak systolic strain rate (SR) was extracted to assess regional myocardial function. Magnetic resonance imaging was performed to assess late-enhancement for the detection of myocardial fibrosis in Fabry patients (n=39). In patients, women <20 years of age had no hypertrophy, no late-enhancement, and normal radial and longitudinal function (SR longitudinal=-1.7+/-0.5 s(-1); P=n.s. compared with controls). Ten women, >20 years of age, had no hypertrophy, no late-enhancement, normal radial and longitudinal function in the septal wall, but reduced longitudinal function in the lateral wall (SR=-1.4+/-0.5 s(-1)). All male patients without hypertrophy and no late-enhancement had normal radial function but reduced longitudinal function in both the septal and lateral walls (SR=-1.3+/-0.3 s(-1)). Patients with hypertrophy but without late-enhancement (n=13) had reduced radial and longitudinal function. Twelve patients displaying hypertrophy and late-enhancement had severely reduced radial and longitudinal function (SR=-1.1+/-0.5 s(-1)). Two of them with the worst impairment of regional function (SR=-0.8+/-0.6 s(-1)) died in the follow-up period. CONCLUSION: These results illustrate the variation of morphological changes and its functional consequences in Fabry cardiomyopathy.
    Eur Heart J. 01/2005; 26(12):1221-7.
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    ABSTRACT: On its own, glucose is a major factor for proliferation of pancreatic beta-cells and is also an essential prerequisite for IGF-I and growth hormone-induced growth of these cells. p8 was originally identified as an emergency gene product upregulated in pancreatic acinar cells in response to acute pancreatitis. p8 was further shown to be involved in a broad range of biological functions, including cell growth, growth arrest, apoptosis, and tumor development. These in part opposite actions may be related to distinct stimuli and pathways in certain conditions and cell types. Here we demonstrate that p8 is widely expressed in human pancreatic islets in vivo and in several beta-cell lines in vitro. Based on this observation, we tested the hypothesis that p8 production in pancreatic beta-cells is regulated by glucose. Incubation of rat INS-1 beta-cells with 25 mmol/l glucose resulted in a continuous increase of proliferating cell numbers. This was accompanied by a strong upregulation of p8 mRNA and protein expression, indicating that p8 is a physiological mediator of glucose-induced pancreatic beta-cell growth. Binding of glucose-activated protein kinase C (PKC) to two PKC sites within a highly conserved region of the p8 protein may be a possible mechanism linking glucose and p8 pathways leading to proliferation.
    Diabetes 03/2004; 53 Suppl 1:S82-5. · 7.90 Impact Factor
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    ABSTRACT: Fabry disease is an X-linked lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase A. The lack of enzyme activity results in an intracellular accumulation of glycosphingolipids, mainly globotriaosylceramide, in various tissues. Significant morbidity is caused by progressive effects on the vascular endothelium, heart, brain and kidney leading to end-stage renal disease. In this review we would like to give a current overview on recent advances in therapy and an outlook on future aspects in the management of Fabry disease. Besides symptomatic management, enzyme replacement therapy with recombinant alpha-galactosidase A is the only specific treatment currently available. Clinical trials using recombinant alpha-galactosidase A showed safety and efficacy in reversing substrate storage in different tissues. Short-term response on clinical manifestations such as impaired kidney function demonstrates a clear potential to improve and stabilize symptoms of the disease. In patients with residual enzyme activity enzyme enhancement therapy with pharmacological chaperones seems to be an attractive approach. Enzyme replacement therapy mediated by gene transfer may become a promising alternative treatment strategy in the future. Remarkable advances in the treatment of patients with Fabry disease have been made with the introduction of enzyme replacement therapy in clinical use. Although lysosomal globotriaosylceramide deposits are cleared very effectively, longer term experience on clinical outcome in patients with severe vital organ involvement is still limited.
    Current Opinion in Nephrology and Hypertension 10/2003; 12(5):491-5. · 3.96 Impact Factor
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    ABSTRACT: Enzyme replacement therapy (ERT) has been shown to enhance microvascular endothelial globotriaosylceramide clearance in the hearts of patients with Fabry disease. Whether these results can be translated into an improvement of myocardial function has yet to be demonstrated. Sixteen patients with Fabry disease who were treated in an open-label study with 1.0 mg/kg body weight of recombinant alpha-Gal A (agalsidase beta, Fabrazyme) were followed up for 12 months. Myocardial function was quantified by ultrasonic strain rate imaging to assess radial and longitudinal myocardial deformation. End-diastolic thickness of the left ventricular posterior wall and myocardial mass (assessed by magnetic resonance imaging, n=10) was measured at baseline and after 12 months of ERT. Data were compared with 16 age-matched healthy controls. At baseline, both peak systolic strain rate and systolic strain were significantly reduced in the radial and longitudinal direction in patients compared with controls. Peak systolic strain rate increased significantly in the posterior wall (radial function) after one year of treatment (baseline, 2.8+/-0.2 s(-1); 12 months, 3.7+/-0.3 s(-1); P<0.05). In addition, end-systolic strain of the posterior wall increased significantly (baseline, 34+/-3%; 12 months, 45+/-4%; P<0.05). This enhancement in radial function was accompanied by an improvement in longitudinal function. End-diastolic thickness of the posterior wall decreased significantly after 12 months of treatment (baseline, 13.8+/-0.6 mm; 12 months, 11.8+/-0.6 mm; P<0.05). In parallel, myocardial mass decreased significantly from 201+/-18 to 180+/-21 g (P<0.05). These results suggest that ERT can decrease left ventricular hypertrophy and improve regional myocardial function.
    Circulation 09/2003; 108(11):1299-301. · 15.20 Impact Factor
  • European Journal of Echocardiography - EUR J ECHOCARDIOGR. 01/2003; 4.