Showing papers by "Andreas Pfeiffer published in 2004"

Transactivation via the human glucocorticoid and mineralocorticoid receptor by therapeutically used steroids in CV-1 cells: a comparison of their glucocorticoid and mineralocorticoid properties

Abstract: Background: Glucocorticoids (GCs) are commonly used for long-term medication in immunosuppressive and anti-inflammatory therapy. However, the data describing gluco- and mineralo-corticoid (MC) properties of widely applied synthetic GCs are often based on diverse clinical observations and on a variety of in vitro tests under various conditions, which makes a quantitative comparison questionable. Method: We compared MC and GC properties of different steroids, often used in clinical practice, in the same in vitro test system (luciferase transactivation assay in CV-1 cells transfected with either hMR or hGRa expression vectors) complemented by a system to test the steroid binding affinities at the hMR (protein expression in T7-coupled rabbit reticulocyte lysate). Results and Conclusions: While the potency of a GC is increased by an 11-hydroxy group, both its potency and its selectivity are increased by the D1-dehydro-configuration and a hydrophobic residue in position 16 (16-methylene, 16a-methyl or 16b-methyl group). Almost ideal GCs in terms of missing MC effects, as defined by our in vitro assay, are therefore prednylidene, budesonide, beclomethasone and betamethasone. The MC potency of a steroid is increased by a 9a -o r a6 a-fluoro substituent. A hydrophilic substituent in position 16 (like 16-hydroxylation in triamcinolone) decreases both MC and GC properties. As no substituent that leads to an isolated reduction of GC activity could be characterized in our experiments, 9a-fluorocortisol, the most frequently used steroid for MC substitution, seems to be the best choice of available steroids for this purpose.

The polycystic ovary syndrome per se is not associated with increased chronic inflammation

Abstract: Objective: The syndrome of polycystic ovaries (PCOS) is a known risk factor for type 2 diabetes. It is not known, however, whether the increase in diabetes risk is related to endocrine abnormalities associated with PCOS such as hyperandrogenemia, or whether it is a consequence of the anthropometric or metabolic alterations frequently observed in PCOS women. Design: Since markers of inflammation are supposed to predict type 2 diabetes, interleukin-6 (IL-6) and C-reactive protein (CRP) in combination with parameters of obesity, insulin resistance and hyperandrogenism were determined in 57 PCOS women and in 20 age-matched healthy controls. In addition, the C-174G IL-6 promoter polymorphism was analyzed as a determinant in influencing IL-6, obesity, and androgen levels in women. Results: Neither CRP nor IL-6 were significantly elevated in lean or obese PCOS women compared with age-matched lean or obese controls. In PCOS patients, variables of body composition (body mass index (BMI), waist to hip ratio, dual-energy X-ray-absorptiometry fat mass) and of insulin resistance were correlated with IL-6 or CRP, while parameters of hyperandogenism were not. Multivariate linear regression analysis revealed that obesity is the dominant force, thus explaining 18% and 24% of the IL-6 or CRP levels, respectively, in PCOS women. No association of IL-6 or BMI to a certain genotype at C-174G could be demonstrated in 50 PCOS patients. The heterozygous GC genotype, however, was associated with lower androstendione levels. Metformin treatment of 9 obese, insulin-resistant PCOS patients over a period of 6 months caused a significant decrease in body weight, body fat mass and total testosterone, but showed no significant decline in IL-6 or CRP concentrations. Conclusions: In PCOS women, plasma levels of IL-6 and CRP were not increased when compared with age- and BMI-matched controls. BMI was, however, the parameter most strongly related to IL-6 and CRP in PCOS; thus PCOS-related endocrine abnormalities do not appear to activate inflammatory parameters thereby enhancing the risk of diabetes. In PCOS, the type 2 diabetes risk may, therefore, be confined to those with obesity and/or metabolic alterations rather than affecting all women suffering from the syndrome.

Adiponectin is independently associated with insulin sensitivity in women with polycystic ovary syndrome.

Abstract: Summary objective The polycystic ovary syndrome (PCOS) is associated with obesity and insulin resistance predisposing to diabetes mellitus type 2 and atherosclerosis. Adiponectin is a recently discovered adipocytokine with insulin-sensitizing and putative antiatherosclerotic properties. The aim of the study was to elucidate determinants of circulating adiponectin levels and to investigate the potential role of adiponectin in insulin resistance in PCOS women. patients and measurements Plasma adiponectin and parameters of obesity, insulin resistance and hyperandrogenism were measured In 62 women with PCOS and in 35 healthy female controls. results Both in PCOS and controls, adiponectin levels were lower in overweight or obese women than in normal-weight women, without any difference between PCOS and controls after adjustment for body mass index (BMI). In PCOS and in controls there was a significant correlation of adiponectin with BMI (r = −0·516, P < 0·001), fasting insulin (r = −0·404, P < 0·001), homeostasis model sensitivity (HOMA %S) (r = −0·424, P < 0·001) and testosterone (r = −0·279, P < 0·01), but no correlation with androstenedione (r = −0·112, P = 0·325), 17-OH-progesterone (r =−0·031, P = 0·784) or the LH/FSH ratio (r =−0·033, P = 0·753). Multiple linear regression analysis revealed that BMI and HOMA %S but not testosterone were independently associated with adiponectin plasma levels, explaining 16% (BMI) and 13% (HOMA %S) of the variability of adiponectin, respectively. In PCOS patients insulin sensitivity, as indicated by continuous infusion of glucose with model assessment (CIGMA %S) was significantly correlated with adiponectin (r = 0·55; P < 0·001), BMI (r =−0·575; P < 0·001), waist-to-hip ratio (WHR) (r =−0·48; P = 0·001), body fat mass assessed by dual-energy X-ray-absorptiometry (DEXA) [Dexa-fat (total) (r = −0·61; P < 0·001) and Dexa-fat (trunk) (r = −0·59; P < 0·001)] and with testosterone (r = −0·42; P = 0·001). Multiple linear regression analysis demonstrated that markers of obesity such as BMI, total or truncal fat mass, age and adiponectin were independently associated with CIGMA %S, and that circulating adiponectin accounted for about 18% of the degree of insulin resistance in PCOS. By contrast, testosterone was not a significant factor, suggesting that PCOS per se did not affect insulin sensitivity independent from obesity, age and adiponectin. Metformin treatment for 6 months in insulin-resistant PCOS women (n = 9) had no effect on plasma adiponectin (P = 0·59) despite significant loss of weight and fat mass and improvement in hyperandrogenaemia. conclusions PCOS per se is not associated with decreased levels of plasma adiponectin. However, circulating adiponectin is independently associated with the degree of insulin resistance in PCOS women and may contribute to the development and/or maintenance of insulin resistance independent from adiposity.

A goodness-of-fit statistical toolkit

Abstract: Statistical methods play a significant role throughout the life-cycle of physics experiments, being an essential component of physics analysis The present project in progress aims to develop an object-oriented software Toolkit for statistical data analysis The Toolkit contains a variety of Goodness-of-Fit (GoF) tests, from Chi-squared to Kolmogorov-Smirnov, to less known, but generally much more powerful tests such as Anderson-Darling, Goodman, Fisz-Cramer-von Mises, Kuiper Thanks to the component-based design and the usage of the standard abstract interfaces for data analysis, this tool can be used by other data analysis systems or integrated in experimental software frameworks In this paper we describe the statistical details of the algorithms and the computational features of the Toolkit With the aim of showing the consistency between the code and the mathematical features of the algorithms, we describe the results we obtained reproducing by means of the Toolkit a couple of Goodness-of-Fit testing examples of relevance in statistics literature

Endogenous and exogenous glucocorticoids decrease plasma ghrelin in humans

Abstract: Objective: The orexigenic and adipogenic peptide hormone ghrelin is predominantly produced and secreted by the stomach and seems to transduce changes in food intake to specific neuronal circuits in the brain. The activity of ghrelin also includes stimulatory effects on the corticotropic system. However, little is known about the influence of glucocorticoids on ghrelin levels. We therefore studied human plasma ghrelin levels in the presence and absence of elevated glucocorticoid levels of either endogenous or exogenous origin. Methods: Plasma ghrelin levels were measured in five patients with chronic hypercortisolism (aged 29 – 58, median 46 years) due to Cushing’s syndrome before and after successful surgery for the adenoma, and in eight healthy controls (aged 24 – 39, median 27.5 years) before and after 30 mg prednisolone (for 5 days) once a day in the morning (median body mass index (BMI) 22.7 kg/m 2 ). Plasma ghrelin levels were measured with a commercially available radioimmunoassay. Results: In patients with Cushing’s syndrome, plasma ghrelin levels were low (median 363.2 pg/ml, range 161.9 – 525.7 pg/ml) and significantly increased by 26.6% (P ¼ 0.04) after successful surgery, while BMI decreased (median 26.2 – 24.0 kg/m 2 , P ¼ 0.04). A strong negative correlation (r ¼ 2 0.9, P ¼ 0.04) between changes in BMI and plasma ghrelin was observed. In healthy controls, plasma ghrelin levels (median 288.7 pg/ml, range 119.6 – 827.8 pg/ml) were significantly suppressed by 18.3% (P ¼ 0.04) after prednisolone treatment. Conclusions: We have shown for the first time that plasma ghrelin levels are decreased under endogenously or exogenously induced hypercortisolism, making ghrelin an unlikely candidate for causing the changes in energy balance or body composition characteristic of Cushing’s disease. However, the reduced ghrelin secretion could reflect a compensation mechanism in reaction to the metabolic consequences of chronic hypercortisolism.

Body Mass Index and C-174G Interleukin-6 Promoter Polymorphism Interact in Predicting Type 2 Diabetes

Abstract: Increased levels of IL-6 add further risk to the impact of obesity in respect to the development of type 2 diabetes mellitus (T2DM). A C-174G polymorphism within the IL-6 promoter region was shown to influence transcription rate of IL-6. We made use of a nested case-control study within the European Prospective Investigation into Cancer and Nutrition-Potsdam cohort of 27,548 individuals, selecting 188 T2DM cases and 376 controls to investigate this polymorphism in respect to development of T2DM. This polymorphism was found to modify the correlation between body mass index (BMI) and IL-6 by showing a much stronger increase of IL-6 at increased BMI for CC genotypes compared with GG genotypes. Interestingly, C-174G polymorphism was found to be an effect modifier for the impact of BMI regarding T2DM. Whereas BMI greater than or equal to 28 kg/m(2) increased the risk of T2DM 3.44-fold [95% confidence interval (CI), 1.34- to 8.24-fold] for GG genotypes and 2.94-fold (95% CI, 1.56- to 5.56-fold) for GC genotypes, we found a 17.68-fold (95% CI, 3.57- to 87.66-fold) increase in risk for CC genotypes. In conclusion, obese individuals with BMI greater than or equal to 28 kg/m(2) carrying the CC genotype showed a more than 5-fold increased risk of developing T2DM compared with the remaining genotypes and, hence, might profit most from weight reduction.

Reduced Hepatic Insulin Extraction in Response to Gastric Inhibitory Polypeptide Compensates for Reduced Insulin Secretion in Normal-Weight and Normal Glucose Tolerant First-Degree Relatives of Type 2 Diabetic Patients

Abstract: Our objective was to study whether young first-degree relatives of patients with type 2 diabetes (FDRs) have altered insulin secretion and insulin clearance in response to gastric inhibitory polypeptide (GIP) in combination with glucose and arginine. A hyperglycemic clamp (11.1 mmol/l for 115 min), followed by addition of GIP (2 pmol. kg(-1). min(-1), 60-115 min) and an arginine bolus and infusion (10 mg. kg(-1). min(-1), 90-115 min), was conducted on 14 healthy volunteers and 13 FDRs. Both groups had normal glucose tolerance. FDRs were more insulin resistant (HOMA(IR)) under basal conditions (P = 0.003). FDRs demonstrated significant global impairment in insulin secretion capacity, which was not specific for one of the secretagogues. Insulin clearance was significantly reduced in the group of FDRs under basal conditions and in response to GIP, but there was no general defect in insulin clearance in response to glucose and arginine. The HOMA(IR) correlated negatively (P < 0.01) with insulin clearance under basal conditions (r = -0.96) and under GIP infusion (r = -0.56). We propose that impairment in insulin secretion capacity and decreased insulin sensitivity is compensated for several mechanisms, one of which includes a GIP-dependent reduction of the insulin clearance that will increase peripheral insulin levels to maintain normoglycemia.

Severe hyponatremia due to hypopituitarism with adrenal insufficiency: Report on 28 cases

Abstract: Severe hyponatremia due to hypopituitarism and adrenal insufficiency can be life-threatening. In our experience, the diagnosis of hypopituitarism in hyponatremic patients is often overlooked. In a retrospective study we screened the files of 185 patients with severe hyponatremia (<130 mmol/l) that had been seen in our endocrinological unit in order to describe the clinical spectrum of patients with hyponatremia and hypopituitarism. In 139 cases it was possible to clearly ascribe the patients to the pathophysiological groups of 1) primary sodium deficiency, 2) edematous disorders, and 3) normovolemic disorders including the Syndrome of Inappropriate ADH Secretion (SIADH). 28 patients with severe „normovolemic hyponatremia“ (mean serum sodium: 116±SD 7 mmol/l) had hypopituitarism and secondary adrenal insufficiency as shown by basal cortisol measurements and dynamic tests of adrenal function. In 25 cases of this group hypopituitarism (mostly due to empty sella, Sheehan’s Syndrome and pituitary tumors) had not been recognised previously, and in 12 cases recurrent hyponatremia during previous hospital admissions (up to four times) could be documented. The most frequently occurring clinical signs were missing or scanty pubic and axillary hair, pale and doughy skin and small testicles in the men. Frequent symptoms like nausea and vomiting, confusion, disorientation, somnolence or coma were similar to those in 91 patients with SIADH. In most patients with hyponatremic hypopituitarism, plasma ADH levels were inappropriately high, probably due to a failure of endogenous cortisol to suppress the hormone in a stressful situation. All patients recovered after low-dose hydrocortisone substitution. Most patients had other pituitary hormone deficiencies and were appropriately substituted subsequently. Hypopituitarism including secondary adrenal insufficiency seems to be a frequently overlooked cause of severe hyponatremia. A high level of suspicion is the best way to recognise the underlying disorder. Treatment with hydrocortisone is very effective.

Endogenous and exogenous glucocorticoids decrease plasma ghrelin in humans

Abstract: Objective: The orexigenic and adipogenic peptide hormone ghrelin is predominantly produced and secreted by the stomach and seems to transduce changes in food intake to specific neuronal circuits in the brain. The activity of ghrelin also includes stimulatory effects on the corticotropic system. However, little is known about the influence of glucocorticoids on ghrelin levels. We therefore studied human plasma ghrelin levels in the presence and absence of elevated glucocorticoid levels of either endogenous or exogenous origin. Methods: Plasma ghrelin levels were measured in five patients with chronic hypercortisolism (aged 29 – 58, median 46 years) due to Cushing’s syndrome before and after successful surgery for the adenoma, and in eight healthy controls (aged 24 – 39, median 27.5 years) before and after 30 mg prednisolone (for 5 days) once a day in the morning (median body mass index (BMI) 22.7 kg/m 2 ). Plasma ghrelin levels were measured with a commercially available radioimmunoassay. Results: In patients with Cushing’s syndrome, plasma ghrelin levels were low (median 363.2 pg/ml, range 161.9 – 525.7 pg/ml) and significantly increased by 26.6% (P ¼ 0.04) after successful surgery, while BMI decreased (median 26.2 – 24.0 kg/m 2 , P ¼ 0.04). A strong negative correlation (r ¼ 2 0.9, P ¼ 0.04) between changes in BMI and plasma ghrelin was observed. In healthy controls, plasma ghrelin levels (median 288.7 pg/ml, range 119.6 – 827.8 pg/ml) were significantly suppressed by 18.3% (P ¼ 0.04) after prednisolone treatment. Conclusions: We have shown for the first time that plasma ghrelin levels are decreased under endogenously or exogenously induced hypercortisolism, making ghrelin an unlikely candidate for causing the changes in energy balance or body composition characteristic of Cushing’s disease. However, the reduced ghrelin secretion could reflect a compensation mechanism in reaction to the metabolic consequences of chronic hypercortisolism.

Application of statistical methods for the comparison of data distributions

Abstract: Data analysis is an essential section of all physics experiments; in spite of this only a few analysis standard toolkits are available Concerning the comparison between distributions, almost all these toolkits are limited to the Chi-squared test Statistics provides a whole chapter of Goodness-of-Fit tests, from the Chi-squared to tests based on maximum distance (Kolmogorov-Smirnov, Kuiper, Goodman), to tests based on quadratic distance (Fisz-Cramer-von Mises, Anderson-Darling, Tiku) All of these Goodness-of-Fit tests have been collected in a new open-source Statistical Toolkit This Toolkit matches a sophisticated statistical data treatment with the most advanced computing techniques, such as object-oriented technology with the use of design patterns and generic programming None of the Goodness-of-Fit tests included in the system is optimum for every case Unfortunately, statistics does not provide a universal recipe for specific distributions and furthermore the only rare available guidelines refer to the comparison between smooth theoretical distributions With the aim of helping the user in the algorithm choice, we present the results of an intrinsic statistical comparison among many of the Goodness-of-Fit tests contained in the Statistical Toolkit in terms of relative efficiency

Enhancement of early- and late-phase insulin secretion and insulin sensitivity by the combination of repaglinide and metformin in type 2 diabetes mellitus.

Abstract: The effects of a combination of repaglinide and metformin on the insulin secretion pattern and insulin sensitivity were studied in a fixed-dose, open-label, placebo-controlled cross-over study. Eleven patients with T2 DM were allocated in random order to treatment with placebo or repaglinide (1 mg pre-meal 3 x/day) in combination with metformin (2550 mg/day) for one-week periods of each. At the end of each period a hyperglycaemic (HC) and a euglycaemic clamp (EC) were performed. Both early (0 - 10 min) and late (25 - 180 min) phases of insulin secretion were significantly increased during HC with repaglinide compared to placebo (263.3 +/- 133.1 vs. 443.6 +/- 138.5 pmol/l/10 min, p = 0.008 and 18 750.9 +/- 5936.4 vs. 34 508.65 +/- 9234.0 pmol/l/25 - 180 min; p = 0.008). The C-peptide concentrations under steady-state conditions were lower in EC with placebo than with repaglinide (p = 0.014). When euglycaemia was achieved in EC, the C-peptide concentrations decreased from hyperglycaemic to normoglycaemic values in the presence of repaglinide but remained higher than after placebo. The insulin sensitivity index (ISI) was increased by 35 % after 1 week of combination therapy with repaglinide plus metformin (1.11 +/- 0.03 x 10 (2) vs. 0.83 +/- 0.21 x 10 (2) mg x kg (-1) body weight x min (-1) x pmol (-1) x l, respectively; p = 0.033). Repaglinide increased early and late phases of insulin responses in HC, without markedly enhancing insulin secretion in euglycaemia. Repaglinide in combination with metformin produced a significant enhancement of ISI, suggesting a synergistic effect on insulin sensitivity.

Experience with software process in physics projects

Abstract: A rigorous software process is known to be one of the key elements for the success of a software project. In spite of its role being widely recognized in software engineering, the adoption of a process is quite unusual in the physics research environment. We present the experience gained in the application of the unified process to a variety of software projects in various experimental domains, and the describe how the process has been adapted to the peculiar characteristics of the scientific research environment.

Status of the LCG Physicist Interface (PI) project

Abstract: In the context of the LHC Computing Grid (LCG) project, the Applications Area develops and maintains that part of the physics applications software and associated infrastructure that is shared among the LHC experiments. In this context, the Physicist Interface (PI) project of the LCG Application Area encompasses the interfaces and tools by which physicists will directly use the software. At present, the project covers analysis services, interactivity (the “physicist's desktop”), and visualization. The project has the mandate to provide a consistent set of interfaces and tools by which physicists will directly use the LCG software. This paper will describe the status of the project, concentrating on the activities in relation to the Analysis Services subsystem.

The LCG PI project: using interfaces for physics data analysis

Abstract: In the context of the LHC Computing Grid (LCG) project, the Applications Area develops and maintains that part of the physics applications software and associated infrastructure that is shared among the LHC experiments. The "Physicist Interface" (PI) project of the LCG Application Area encompasses the interfaces and tools by which physicists will directly use the software, providing implementations based on agreed standards like the AIDA interfaces for data analysis. In collaboration with users from the experiments, work has started with implementing the AIDA interfaces for (binned and unbinned) histogramming, fitting and minimization as well as manipulation of tuples. These implementations have been developed by re-using existing packages either directly or by using a (thin) layer of wrappers. In addition, bindings of these interfaces to the Python interpreted language have been done using the dictionary subsystem of the LCG-AA/SEAL project. The actual status and the future planning of the project will be presented.

Function of human mineralocorticoid receptor splice variant.

Abstract: In their recent paper, Pascual-Le Tallec et al. (1) state that a publication by Bloem et al. (2) describes that a mineralocorticoid receptor (MR) splice variant with a 12 bp insertion coding for a protein with four additional amino acids (MRþ4) shows no functional difference to the MR without insertion. This evidence is not produced in the publication by Bloem et al. or to our knowledge anywhere else. On the contrary Bloem et al. propose that the additional four amino acid residues in the DNA binding domain could alter binding to a glucocorticoid response element (GRE) and transcription activation. Because this splice variant shows considerable concentrations in various human tissues (3), we have compared transactivation mediated by MR and MRþ4. The plasmid pchMRþ12 coding for hMRþ4 was created by in vitro PCR mutagenesis of pchMR coding for hMR. Transactivation of both variants by aldosterone was analysed in CV-1 cells by measuring firefly luciferase activity of an inducible reporter gene normalised to the activity of constitutively expressed renilla luciferase (Fig. 1) (4).