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Search Results: 1 - 10 of 19172 matches for " Richard Sparla "
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Uptake of long chain fatty acids is regulated by dynamic interaction of FAT/CD36 with cholesterol/sphingolipid enriched microdomains (lipid rafts)
Robert Ehehalt, Richard Sparla, Hasan Kulaksiz, Thomas Herrmann, Joachim Füllekrug, Wolfgang Stremmel
BMC Cell Biology , 2008, DOI: 10.1186/1471-2121-9-45
Abstract: Dynamic association of FAT/CD36 a candidate fatty acid transporter with lipid rafts was analysed by isolation of detergent resistant membranes (DRMs) and by clustering of lipid rafts with antibodies on living cells. Lipid raft integrity was modulated by cholesterol depletion using methyl-β-cyclodextrin and sphingolipid depletion using myriocin and sphingomyelinase. Functional analyses were performed using an [3H]-oleate uptake assay.Overexpression of FAT/CD36 and FATP4 increased long chain fatty acid uptake. The uptake of long chain fatty acids was cholesterol and sphingolipid dependent. Floating experiments showed that there are two pools of FAT/CD36, one found in DRMs and another outside of these domains. FAT/CD36 co-localized with the lipid raft marker PLAP in antibody-clustered domains at the plasma membrane and segregated away from the non-raft marker GFP-TMD. Antibody cross-linking increased DRM association of FAT/CD36 and accelerated the overall fatty acid uptake in a cholesterol dependent manner. Another candidate transporter, FATP4, was neither present in DRMs nor co-localized with FAT/CD36 at the plasma membrane.Our observations suggest the existence of two pools of FAT/CD36 within cellular membranes. As increased raft association of FAT/CD36 leads to an increased fatty acid uptake, dynamic association of FAT/CD36 with lipid rafts might regulate the process. There is no direct interaction of FATP4 with lipid rafts or raft associated FAT/CD36. Thus, lipid rafts have to be considered as targets for the treatment of lipid disorders.Uptake of long chain fatty acids (LCFAs) is important for many cellular functions and the understanding of the uptake mechanisms is an important target for treatment of lipid disorders [1-4]. The molecular mechanisms of fatty acid transport across the plasma membrane are still a matter of debate and the predominating mechanism likely differs from cell to cell (for reviews see [5-8]). In general, two possible groups of mechanisms ar
Increased basolateral sorting of carcinoembryonic antigen in a polarized colon carcinoma cell line after cholesterol depletion-Implications for treatment of inflammatory bowel disease
Robert Ehehalt, Markus Krautter, Martin Zorn, Richard Sparla, Joachim Füllekrug, Hasan Kulaksiz, Wolfgang Stremmel
World Journal of Gastroenterology , 2008,
Abstract: AIM: To investigate a possible increase of basolateral expression of carcinoembryonic antigen (CEA) by interfering with the apical transport machinery, we studied the effect of cholesterol depletion on CEA sorting and secretion.METHODS: Cholesterol depletion was performed in polarized Caco-2 cells using lovastatin and methyl-β-cyclodextrin.RESULTS: We show that CEA is predominantly expressed and secreted at the apical surface. Reduction of the cholesterol level of the cell by 40%-50% with lovastatin and methyl-β-cyclodextrin led to a significant change of the apical-to-basolateral transport ratio towards the basolateral membrane.CONCLUSION: As basolateral expression of CEA has been suggested to have anti-inflammatory properties, Cholesterol depletion of enterocytes might be a potential approach to influence the course of inflammatory bowel disease.
A classification of centrally-symmetric and cyclic 12-vertex triangulations of $S^2 \times S^2$
G. Lassmann,E. Sparla
Mathematics , 1998,
Abstract: In this paper our main result states that there exist exactly three combinatorially distinct centrally-symmetric 12-vertex-triangulations of the product of two 2-spheres with a cyclic symmetry. We also compute the automorphism groups of the triangulations. These instances suggest that there is a triangulation of $S^2 \times S^2$ with 11 vertices -- the minimum number of vertices required.
The Skeletal Organic Matrix from Mediterranean Coral Balanophyllia europaea Influences Calcium Carbonate Precipitation
Stefano Goffredo,Patrizia Vergni,Michela Reggi,Erik Caroselli,Francesca Sparla,Oren Levy,Zvy Dubinsky,Giuseppe Falini
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0022338
Abstract: Scleractinian coral skeletons are made mainly of calcium carbonate in the form of aragonite. The mineral deposition occurs in a biological confined environment, but it is still a theme of discussion to what extent the calcification occurs under biological or environmental control. Hence, the shape, size and organization of skeletal crystals from the cellular level through the colony architecture, were attributed to factors as diverse as mineral supersaturation levels and organic mediation of crystal growth. The skeleton contains an intra-skeletal organic matrix (OM) of which only the water soluble component was chemically and physically characterized. In this work that OM from the skeleton of the Balanophyllia europaea, a solitary scleractinian coral endemic to the Mediterranean Sea, is studied in vitro with the aim of understanding its role in the mineralization of calcium carbonate. Mineralization of calcium carbonate was conducted by overgrowth experiments on coral skeleton and in calcium chloride solutions containing different ratios of water soluble and/or insoluble OM and of magnesium ions. The precipitates were characterized by diffractometric, spectroscopic and microscopic techniques. The results showed that both soluble and insoluble OM components influence calcium carbonate precipitation and that the effect is enhanced by their co-presence. The role of magnesium ions is also affected by the presence of the OM components. Thus, in vitro, OM influences calcium carbonate crystal morphology, aggregation and polymorphism as a function of its composition and of the content of magnesium ions in the precipitation media. This research, although does not resolve the controversy between environmental or biological control on the deposition of calcium carbonate in corals, sheds a light on the role of OM, which appears mediated by the presence of magnesium ions.
The Protein Phosphatase 7 Regulates Phytochrome Signaling in Arabidopsis
Thierry Genoud, Marcela Trevi?o Santa Cruz, Tea Kulisic, Francesca Sparla, Christian Fankhauser, Jean-Pierre Métraux
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002699
Abstract: The psi2 mutant of Arabidopsis displays amplification of the responses controlled by the red/far red light photoreceptors phytochrome A (phyA) and phytochrome B (phyB) but no apparent defect in blue light perception. We found that loss-of-function alleles of the protein phosphatase 7 (AtPP7) are responsible for the light hypersensitivity in psi2 demonstrating that AtPP7 controls the levels of phytochrome signaling. Plants expressing reduced levels of AtPP7 mRNA display reduced blue-light induced cryptochrome signaling but no noticeable deficiency in phytochrome signaling. Our genetic analysis suggests that phytochrome signaling is enhanced in the AtPP7 loss of function alleles, including in blue light, which masks the reduced cryptochrome signaling. AtPP7 has been found to interact both in yeast and in planta assays with nucleotide-diphosphate kinase 2 (NDPK2), a positive regulator of phytochrome signals. Analysis of ndpk2-psi2 double mutants suggests that NDPK2 plays a critical role in the AtPP7 regulation of the phytochrome pathway and identifies NDPK2 as an upstream element involved in the modulation of the salicylic acid (SA)-dependent defense pathway by light. Thus, cryptochrome- and phytochrome-specific light signals synchronously control their relative contribution to the regulation of plant development. Interestingly, PP7 and NDPK are also components of animal light signaling systems.
On the Prevention of Obesity and a Philosophy for Healthy Living  [PDF]
Richard Visser
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.37128
Abstract: Overweight and obesity have now reached historical, maximal peak values, with nearly one-third of world population suffering from these conditions. We are now witnessing the impact of this epidemic upon the global health status, with non-communicable diseases on the rise. We have also witnessed the shortcomings and failures of past actions taken when obesity is already present. In this essay the author reviews efforts made in the past regarding identification and treatment of obesity, and propose that actions should be taken before the onset of this disease, by motivating people to make intelligent, healthy choices when it comes to food and physical activity. A philosophy for healthy living should become central to the intervention actions, for them to be successful and sustained. Prevention of obesity should involve all those concerned irregardless of their position in society and curricular training, in order to create a multi-lateral, multi-national effort that will protect our families and our children from the consequences of this epidemic.
A Supportive Approach to Supervising Students Reading for a Phd in Systems and Software Engineering  [PDF]
Richard Lai
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326138
Abstract: Supervising a PhD student is a complex teaching task as it involves a very unstructured environment and many intellectual challenges and stimuli, and it often requires a compatible student/supervisor relationship for successful outcomes. It is therefore not surprising that it has been reported that an aspect of teaching and learning that has been overlooked in higher education is research student supervision. Typical problems of poor supervision include: high rates of dissatisfaction with supervisors and high attrition rates and slow rates of completion for students. It has also been reported that there is no set prescription on appropriate and successful supervision; rather, the interactions between quality and style of supervision, and the field of study have all to be considered. It is not easy to know what a student and his/her supervisor should be doing in order to succeed. We are thus motivated to present in this paper our approach to supervising students reading for a PhD in systems and software engineering. This approach is centered on motivating students to learn and to do research by having supervisory activities that support their development throughout their candidature.
The Evolution of Curriculum Development in the Context of Increasing Social and Environmental Complexity  [PDF]
Richard Plate
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.38192
Abstract: The history of curriculum development has been characterized and a series of “crises” with the pendulum shifting between traditionalists’ call for getting back to the basics and the progressives’ focus on the learner. However, tracing this history, one can see a common theme in the criticisms expressed by both parties: the failure of the existing curriculum to meet the demands presented by an increasingly complex society. I follow this theme in order to provide historical context for contemporary calls by scientists and educators for wider use of systems-oriented curricula (i.e. curricula designed to improve systems thinking) at primary, secondary, and tertiary levels of education. With this context, one can view these current calls not as a radical shift of direction, but as a logical next stage in the evolution of curriculum. I conclude with a call for more research assessing the effectiveness of systems-oriented instruction and provide guidelines for enhancing the usefulness of such research in the current United States system.
Sino-French Engineering Curriculums: An Ongoing Process for Elitist Education?  [PDF]
Richard Mariom
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.37B048
Abstract: Here is a multisite case-study paper presenting Sino-French engineering education reform cooperation process. This questions the consequences for the introduction of a hybrid framework in a both dynamic and dichotomous innovation context such as Chinese one.
Kant’s Emergence and Sellarsian Cognitive Science  [PDF]
Richard McDonough
Open Journal of Philosophy (OJPP) , 2014, DOI: 10.4236/ojpp.2014.41007
Abstract:

The paper argues, against current views that see Kant as giving abstract descriptions of cognitive mechanisms (after the fashion of functionalism in cognitive science), that Kant sees mental phenomena as akin to emergent phenomena in a sense traditionally opposed to mechanism. After distinguishing several relevant notions of emergence, the paper distinguishes several of Kant’s basic emergentist theses, including his emergent materialism in chemistry and a species of mental emergence modelled on that chemical emergence. However, Kant’s doctrine of the epigenesis of pure Reason is argued to be Kant’s most fundamental emergentist thesis. The paper argues that Kant’s notion of mental emergence sheds light on some very puzzling aspects of his remarks about the unity of intuition and concept emphasized by Wilfrid Sellars. The paper sketches some of the problems in contemporary cognitive science and shows how a Sellarsian emergentism inspired by Kant addresses some of these problems and provides an interesting alternative to the kind of mechanistic positions that have tended to dominate the field. Finally, the paper locates the present emergentist reading with respect to the perspectivist reading of Kant.

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