945 resultados para Multiple abstraction levels


Relevância:

40.00% 40.00%

Publicador:

Resumo:

The role of the gluco-incretin hormones GIP and GLP-1 in the control of beta cell function was studied by analyzing mice with inactivation of each of these hormone receptor genes, or both. Our results demonstrate that glucose intolerance was additively increased during oral glucose absorption when both receptors were inactivated. After intraperitoneal injections, glucose intolerance was more severe in double- as compared to single-receptor KO mice, and euglycemic clamps revealed normal insulin sensitivity, suggesting a defect in insulin secretion. When assessed in vivo or in perfused pancreas, insulin secretion showed a lack of first phase in Glp-1R(-/-) but not in Gipr(-/-) mice. In perifusion experiments, however, first-phase insulin secretion was present in both types of islets. In double-KO islets, kinetics of insulin secretion was normal, but its amplitude was reduced by about 50% because of a defect distal to plasma membrane depolarization. Thus, gluco-incretin hormones control insulin secretion (a) by an acute insulinotropic effect on beta cells after oral glucose absorption (b) through the regulation, by GLP-1, of in vivo first-phase insulin secretion, probably by an action on extra-islet glucose sensors, and (c) by preserving the function of the secretory pathway, as evidenced by a beta cell autonomous secretion defect when both receptors are inactivated.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

We conducted a genome-wide scan using variance components linkage analysis to localize quantitative-trait loci (QTLs) influencing triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol, and total cholesterol (TC) levels in 3,071 subjects from 459 families with atherogenic dyslipidemia. The most significant evidence for linkage to TG levels was found in a subset of Turkish families at 11q22 [logarithm of the odds ratio (LOD)=3.34] and at 17q12 (LOD=3.44). We performed sequential oligogenic linkage analysis to examine whether multiple QTLs jointly influence TG levels in the Turkish families. These analyses revealed loci at 20q13 that showed strong epistatic effects with 11q22 (conditional LOD=3.15) and at 7q36 that showed strong epistatic effects with 17q12 (conditional LOD=3.21). We also found linkage on the 8p21 region for TG in the entire group of families (LOD=3.08). For HDL-C levels, evidence of linkage was identified on chromosome 15 in the Turkish families (LOD=3.05) and on chromosome 5 in the entire group of families (LOD=2.83). Linkage to QTLs for TC was found at 8p23 in the entire group of families (LOD=4.05) and at 5q13 in a subset of Turkish and Mediterranean families (LOD=3.72). These QTLs provide important clues for the further investigation of genes responsible for these complex lipid phenotypes. These data also indicate that a large proportion of the variance of TG levels in the Turkish population is explained by the interaction of multiple genetic loci.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The objective of the present study was to determine if there is a relationship between serum levels of brain-derived neurotrophic factor (BDNF) and the number of T2/fluid-attenuated inversion recovery (T2/FLAIR) lesions in multiple sclerosis (MS). The use of magnetic resonance imaging (MRI) has revolutionized the study of MS. However, MRI has limitations and the use of other biomarkers such as BDNF may be useful for the clinical assessment and the study of the disease. Serum was obtained from 28 MS patients, 18-50 years old (median 38), 21 women, 0.5-10 years (median 5) of disease duration, EDSS 1-4 (median 1.5) and 28 healthy controls, 19-49 years old (median 33), 19 women. BDNF levels were measured by ELISA. T1, T2/FLAIR and gadolinium-enhanced lesions were measured by a trained radiologist. BDNF was reduced in MS patients (median [range] pg/mL; 1160 [352.6-2640]) compared to healthy controls (1640 [632.4-4268]; P = 0.03, Mann-Whitney test) and was negatively correlated (Spearman correlation test, r = -0.41; P = 0.02) with T2/FLAIR (11-81 lesions, median 42). We found that serum BDNF levels were inversely correlated with the number of T2/FLAIR lesions in patients with MS. BDNF may be a promising biomarker of MS.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

We have described that MMP-9 C- T-1562 and (CA)(n) polymorphisms contribute to multiple sclerosis (MS). Here, we evaluate whether plasma MMP-9 levels are related to disease severity, drug therapy resistance and polymorphisms. For sub-study 1, 36 patients with MS and 35 controls were recruited. For sub-study 2, 88 individuals (53 patients and 35 controls) were included in a cross-sectional analysis. MS patients presented higher MMP-9 activity (1.4 +/- 0.18 versus 0.93 +/- 0.18 A.U. for control, P<0.05). Drug-therapy resistant individuals exhibited increased MMP-9 activity (1.96 +/- 0.25 versus 1.21 +/- 0.09 A.U. for non-resistant patients). EDSS score was also related to MMP-9 levels. The CT + TT and HH genotypes had higher MMP-9 levels as compared to patients carrying the CC and LL Drug therapy resistance, disease severity. MMP-9 plasma activity and polymorphisms are associated with MS. (C) 2012 Elsevier B.V. All rights reserved.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The objective of the present study was to determine if there is a relationship between serum levels of brain-derived neurotrophic factor (BDNF) and the number of T2/fluid-attenuated inversion recovery (T2/FLAIR) lesions in multiple sclerosis (MS). The use of magnetic resonance imaging (MRI) has revolutionized the study of MS. However, MRI has limitations and the use of other biomarkers such as BDNF may be useful for the clinical assessment and the study of the disease. Serum was obtained from 28 MS patients, 18-50 years old (median 38), 21 women, 0.5-10 years (median 5) of disease duration, EDSS 1-4 (median 1.5) and 28 healthy controls, 19-49 years old (median 33), 19 women. BDNF levels were measured by ELISA. T1, T2/FLAIR and gadolinium-enhanced lesions were measured by a trained radiologist. BDNF was reduced in MS patients (median [range] pg/mL; 1160 [352.6-2640]) compared to healthy controls (1640 [632.4-4268]; P = 0.03, Mann-Whitney test) and was negatively correlated (Spearman correlation test, r = -0.41; P = 0.02) with T2/FLAIR (11-81 lesions, median 42). We found that serum BDNF levels were inversely correlated with the number of T2/FLAIR lesions in patients with MS. BDNF may be a promising biomarker of MS.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

High-dose chemotherapy with autologous stem cell transplantation is a cornerstone in the first-line treatment of multiple myeloma patients. However, only few factors have been identified affecting the outcome in such patients. We hypothesised that varying levels of mobilised CD34+ cells confer prognostic information in myeloma patients undergoing high-dose chemotherapy.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Elimination of autoreactive T cells by apoptosis is critical for restricting immune responses to self-antigens. An errant lytic interaction between the CD95 death receptor and its ligand CD95L is presumed to be involved in the pathogenesis of multiple sclerosis (MS). Statins are promising agents for the treatment of MS and were shown to modulate levels of soluble death receptors. Here, we evaluated the in vivo effects by interferon (IFN)-beta and atorvastatin on soluble CD95 (sCD95) and sCD95L in serum of patients with MS. Concentrations of sCD95 and sCD95L did not show any differences between MS and healthy control subjects. In patients with MS, treatment with IFN-beta increased serum levels of sCD95 and sCD95L significantly (P < 0.01 and P < 0.05 respectively). Addition of atorvastatin to IFN-beta did not alter serum levels of sCD95 and sCD95L significantly. Our study suggests that atorvastatin does not affect IFN-beta-induced increases of the soluble death receptors in the serum of patients with MS.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

BACKGROUND Histamine is an ubiquitous inflammatory mediator of numerous physiological processes. Histamine and its receptors have been implicated in multiple sclerosis (MS) disease pathogenesis. We prospectively enrolled 36 MS patients and 19 age and gender-matched healthy volunteers for cerebrospinal fluid (CSF) histamine analysis. FINDINGS CSF HISTAMINE LEVELS IN MS PATIENT SAMPLES WERE SIGNIFICANTLY HIGHER (MEDIAN: 35.6 pg/ml) than in controls (median: 5.5 pg/ml; Beta = 0.525, p < 0.001). In addition, histamine increased with age (Pearson's correlation, p < 0.003). CONCLUSIONS Histamine may be an important factor for both the initiation and maintenance of chronic inflammatory diseases of the central nervous system. Our observation encourages a deeper investigation of the role of histamine in MS.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The mammalian subventricular zone (SVZ) of the lateral wall of the forebrain ventricle retains a population of proliferating neuronal precursors throughout life. Neuronal precursors born in the postnatal and adult SVZ migrate to the olfactory bulb where they differentiate into interneurons. Here we tested the potential of mouse postnatal SVZ precursors in the environment of the embryonic brain: (i) a ubiquitous genetic marker, (ii) a neuron-specific transgene, and (iii) a lipophilic-dye were used to follow the fate of postnatal day 5–10 SVZ cells grafted into embryonic mouse brain ventricles at day 15 of gestation. Graft-derived cells were found at multiple levels of the neuraxis, including septum, thalamus, hypothalamus, and in large numbers in the midbrain inferior colliculus. We observed no integration into the cortex. Neuronal differentiation of graft derived cells was demonstrated by double-staining with neuron-specific β-tubulin antibodies, expression of the neuron-specific transgene, and the dendritic arbors revealed by the lipophilic dye. We conclude that postnatal SVZ cells can migrate through and differentiate into neurons within multiple embryonic brain regions other than the olfactory bulb.

Relevância:

40.00% 40.00%

Publicador:

Relevância:

40.00% 40.00%

Publicador:

Resumo:

In this study, we developed a DEA-based performance measurement methodology that is consistent with performance assessment frameworks such as the Balanced Scorecard. The methodology developed in this paper takes into account the direct or inverse relationships that may exist among the dimensions of performance to construct appropriate production frontiers. The production frontiers we obtained are deemed appropriate as they consist solely of firms with desirable levels for all dimensions of performance. These levels should be at least equal to the critical values set by decision makers. The properties and advantages of our methodology against competing methodologies are presented through an application to a real-world case study from retail firms operating in the US. A comparative analysis between the new methodology and existing methodologies explains the failure of the existing approaches to define appropriate production frontiers when directly or inversely related dimensions of performance are present and to express the interrelationships between the dimensions of performance.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

In this concluding chapter, we bring together the threads and reflections on the chapters contained in this text and show how they relate to multi-level issues. The book has focused on the world of Human Resource Management (HRM) and the systems and practices it must put in place to foster innovation. Many of the contributions argue that in order to bring innovation about, organisations have to think carefully about the way in which they will integrate what is, in practice, organisationally relevant — but socially distributed — knowledge. They need to build a series of knowledge-intensive activities and networks, both within their own boundaries and across other important external inter-relationships. In so doing, they help to co-ordinate important information structures. They have, in effect, to find ways of enabling people to collaborate with each other at lower cost, by reducing both the costs of their co-ordination and the levels of unproductive search activity. They have to engineer these behaviours by reducing the risks for people that might be associated with incorrect ideas and help individuals, teams and business units to advance incomplete ideas that are so often difficult to codify. In short, a range of intangible assets must flow more rapidly throughout the organisation and an appropriate balance must be found between the rewards and incentives associated with creativity, novelty and innovation, versus the risks that innovation may also bring.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Arsenic trioxide (ATO) has been tested in relapsed/refractory multiple myeloma with limited success. In order to better understand drug mechanism and resistance pathways in myeloma we generated an ATO-resistant cell line, 8226/S-ATOR05, with an IC50 that is 2–3-fold higher than control cell lines and significantly higher than clinically achievable concentrations. Interestingly we found two parallel pathways governing resistance to ATO in 8226/S-ATOR05, and the relevance of these pathways appears to be linked to the concentration of ATO used. We found changes in the expression of Bcl-2 family proteins Bfl-1 and Noxa as well as an increase in cellular glutathione (GSH) levels. At low, clinically achievable concentrations, resistance was primarily associated with an increase in expression of the anti-apoptotic protein Bfl-1 and a decrease in expression of the pro-apoptotic protein Noxa. However, as the concentration of ATO increased, elevated levels of intracellular GSH in 8226/S-ATOR05 became the primary mechanism of ATO resistance. Removal of arsenic selection resulted in a loss of the resistance phenotype, with cells becoming sensitive to high concentrations of ATO within 7 days following drug removal, indicating changes associated with high level resistance (elevated GSH) are dependent upon the presence of arsenic. Conversely, not until 50 days without arsenic did cells once again become sensitive to clinically relevant doses of ATO, coinciding with a decrease in the expression of Bfl-1. In addition we found cross-resistance to melphalan and doxorubicin in 8226/S-ATOR05, suggesting ATO-resistance pathways may also be involved in resistance to other chemotherapeutic agents used in the treatment of multiple myeloma.