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Lipid Structure (lipid + structure)
Selected AbstractsCharacterization of the Triacylglycerol Crystal Formation in Adipose Tissue During a Vehicle CollisionJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Barbara H. Stuart Ph.D. Abstract:, The unusual appearance of crystalline fat structures was observed during the postmortem examination of a motor vehicle accident victim. The crystal structures were characterized using Fourier transform infrared spectroscopy and x-ray diffractometry. The structures were found to be made of triacylglycerols, a dominant lipid structure found in human adipose tissue, capable of forming various polymorphic structures. The morphology of the crystalline material was found using both techniques to be predominantly the ,, form of triacylglycerols. The accelerated growth of such triacylglycerol morphology has been observed as a result of shear stresses in other studies involving edible fats. As a result of the findings of this study, it is proposed that increased shear forces may be responsible for the formation of the unusual fat structure found in the victim. An understanding of the effect of forces on the structure of body fat in high-impact collisions can potentially assist in verifying a high-velocity impact. [source] The ,-amyloid protein of Alzheimer's disease binds to membrane lipids but does not bind to the ,7 nicotinic acetylcholine receptorJOURNAL OF NEUROCHEMISTRY, Issue 6 2007David H. Small Abstract Accumulation of the amyloid protein (A,) in the brain is an important step in the pathogenesis of Alzheimer's disease. However, the mechanism by which A, exerts its neurotoxic effect is largely unknown. It has been suggested that the peptide can bind to the ,7 nicotinic acetylcholine receptor (,7nAChR). In this study, we examined the binding of A,1-42 to endogenous and recombinantly expressed ,7nAChRs. A,1-42 did neither inhibit the specific binding of ,7nAChR ligands to rat brain homogenate or slice preparations, nor did it influence the activity of ,7nAChRs expressed in Xenopus oocytes. Similarly, A,1-42 did not compete for ,-bungarotoxin-binding sites on SH-SY5Y cells stably expressing ,7nAChRs. The effect of the A,1-42 on tau phosphorylation was also examined. Although A,1-42 altered tau phosphorylation in ,7nAChR-transfected SH-SY5Y cells, the effect of the peptide was unrelated to ,7nAChR expression or activity. Binding studies using surface plasmon resonance indicated that the majority of the A, bound to membrane lipid, rather than to a protein component. Fluorescence anisotropy experiments indicated that A, may disrupt membrane lipid structure or fluidity. We conclude that the effects of A, are unlikely to be mediated by direct binding to the ,7nAChR. Instead, we speculate that A, may exert its effects by altering the packing of lipids within the plasma membrane, which could, in turn, influence the function of a variety of receptors and channels on the cell surface. [source] Effect of vitamin C and zinc on osmotic fragility and lipid peroxidation in zinc-deficient haemodialysis patientsCELL BIOCHEMISTRY AND FUNCTION, Issue 2 2002Ferda Candan Abstract Peroxidation of the membrane lipid structure of red blood cell leads to haemolysis and anaemia in haemodialysis patients. Dietary constituents of antioxidant vitamins and trace elements may play an important role in protecting against oxidant damage. In this study, the effects of supplementation of vitamin C and zinc on osmotic fragility and lipid peroxidation of erythrocytes were investigated in 34 zinc-deficient haemodialysis patients. Sixteen sex- and age-matched normal volunteers acted as controls. Patients were randomized to receive vitamin C (250 mg day,1), zinc (20 mg day,1) or a placebo treatment for 3 months. The levels of vitamin C, zinc, malondialdehyde (MDA) and osmotic fragility were measured initially and 3 months after supplementation. Mean serum concentration of vitamin C and zinc increased significantly in the groups at the end of the respective study periods. Supplementation with vitamin C and zinc improved osmotic fragility, and decreased the level of MDA in the groups, but some side-effects (i.e. nausea, vomiting, fever, muscle pain, weakness) were observed during the zinc treatment. The results showed that the supplementation of both treatments decreased osmotic fragilty and MDA in zinc-deficient haemodialysis patients. However, vitamin C treatment was found to be safer than zinc supplementation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Towards a specific characterisation of components on a cell surface,combined TERS-investigations of lipids and human cellsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2009R. Böhme Abstract Supported lipid structures and human cells (human dermal derived keratinocyte, HaCaT) were investigated using tip-enhanced Raman spectroscopy (TERS) to use the high spatial resolution capabilities of TERS, which is assumed to be less than 10 nm, to determine specific components on the cell surface. As lipids are a main component of cellular membranes, the correlation of spectral properties of pure lipids with respect to the complex biological sample was investigated. Induced by dynamic structural changes as well as nanoscale effects, a particular spectral feature of the lipid TERS spectra is found to vary, and a similar spectral deviation appears among the TERS spectra measured on the cell. Modifications of the cell surface alone cannot cause such behaviour. In contrast to soft lipid agglomerates, the cells were fixed and therefore hampered for intrinsic structural changes. Hence, the main contribution for the cell TERS spectra variation results from nanoscale effects, determined by different spectral characteristics compared to conventional Raman spectroscopy. The present results demonstrate the capability of TERS to provide a detailed and fast insight into the composition of the cell surface, even allowing the detection of single components. Copyright © 2009 John Wiley & Sons, Ltd. [source] TEXTURAL CHANGES IN CHOCOLATE CHARACTERIZED BY INSTRUMENTAL AND SENSORY TECHNIQUESJOURNAL OF TEXTURE STUDIES, Issue 4 2009LIA M. ANDRAE-NIGHTINGALE ABSTRACT Cocoa butter has a distinct texture due to unique interactions of polymorphic lipid structures. Part of chocolate's appeal is smooth mouthfeel; as fat or sugar bloom forms, textural change is perceived. Correlation of instrumental and sensory texture analysis has not been conducted in stored chocolate. The objective of this study was to analyze texture and color of dark and milk chocolate stored under conditions leading to fat and/or sugar bloom by instrumental and sensory measurements. Milk and dark chocolate was stored 5 weeks at various temperatures and relative humidity (RH), followed by instrumental and sensory texture analysis. All attributes, except springiness, were significantly affected by treatments. According to partial least squares linear regression, instrumental hardness, cohesiveness, chewiness and gumminess modeled sensory hardness. The 30.0C incubator experienced temperature fluctuations, resulting in severe fat bloom. Temperature fluctuations during storage had more influence on texture perception than storage at high temperatures or high RH. PRACTICAL APPLICATIONS This research serves as an initial study on textural aspects of chocolate quality upon storage that is the first report to correlate instrumental textural analysis of chocolate to sensory evaluation. Storage temperature and humidity of chocolate greatly impacts consumer texture perception, which is valuable information to small chocolate handlers and manufacturers who have noted to us that many of the larger companies may have this information , but it is not widely available. It also sets the stage for more detailed studies on texture and flavor of chocolate during storage. Although many storage studies on chocolate exist, those that intertwine studies of quality from both an instrumental and a sensory standpoint are lacking. [source] | |||||||||||||