Lipid arrays

Recently, a quantitative electrospray ionization/mass spectrometry method (ESI/MS) has been developed to analyze the molecular profile, or hpidome of different lipid classes in very small samples. In this method, total lipid extracts from tissues or cultured cells can be directly analyzed. By manipulating the ionization method, the mass spectrographs of polar or even non-polar lipids can be obtained [8]. This method and the use of lipid arrays allow precise and quantitative identification of the lipid profile of a given tissue, and map functional changes that occur. 

This behavior of the DPoPE/cationic PC mixtures is not surprising, because both the double bonds and hydrocarbon chain length variations are known to have considerable effect on the lamellar-to-nonlamellar transitions in lipids [113]. A specific structural characteristic of lipid arrays that exhibits distinct change around the chain length of 14 carbons is the formation of inverted bicontinuous cubic phases Qn. The latter phases tend to form in diacyl or dialkyl phospholipids... 

Ivanova PT, Milne SB, Forrester JS, Brown HA. LIPID arrays new tools in the understanding of membrane dynamics and Upid signaling. Mol. Interv. 2004 4 86-96. 

Amorphous polymer blends present unique challenges to hoth the experimentalist and the theorist, and, from an experimental perspective, often demand more creativity in extracting useful metrics than crystalline materials. Amorphous macromolecules, and their mixtures, challenge our notions on thermodynamic equilibrium, and require a time-dependent perspective. However, amorphous blends play key roles not only in materials and composites science but also in biological and life sciences where the transient structure of proteins and enzymes, membranes, lipid arrays, and many other dynamic structures control function. Fundamental insights gained from investigating the unique aspects of synthetic amorphous blends directly relate to complex systems in the life sciences, and also provide new directions for materials science development. 

Finally, Berger et al [192] have developed a teclmique whereby an array of force curves is obtained over the sample surface ( force-curve mapping ), enabling a map of the tip-sample adliesion to be obtained. The autiiors have used this approach to image differently oriented phase domains of Langimiir-Blodgett-deposited lipid films. 

The spatial arrangement of atoms in two-dimensional protein arrays can be detennined using high-resolution transmission electron microscopy [20]. The measurements have to be carried out in high vacuum, but since tire metliod is used above all for investigating membrane proteins, it may be supposed tliat tire presence of tire lipid bilayer ensures tliat tire protein remains essentially in its native configuration. 

A method which uses supercritical fluid/solid phase extraction/supercritical fluid chromatography (SE/SPE/SEC) has been developed for the analysis of trace constituents in complex matrices (67). By using this technique, extraction and clean-up are accomplished in one step using unmodified SC CO2. This step is monitored by a photodiode-array detector which allows fractionation. Eigure 10.14 shows a schematic representation of the SE/SPE/SEC set-up. This system allowed selective retention of the sample matrices while eluting and depositing the analytes of interest in the cryogenic trap. Application to the analysis of pesticides from lipid sample matrices have been reported. In this case, the lipids were completely separated from the pesticides. 

The antiinflammatory effects of statins likely result from their ability to inhibit the formation of mevalonic acid. Downstream products of this molecule include not only the end product, cholesterol, but also several isoprenoid intermediates that covalently modify ( pre-nylate ) certain key intracellular signaling molecules. Statin treatment reduces leukocyte adhesion, accumulation of macrophages, MMPs, tissue factor, and other proinflammatory mediators. By acting on the MHC class II transactivator (CIITA), statins also interfere with antigen presentation and subsequent T-cell activation. Statin treatment can also limit platelet activation in some assays as well. All these results support the concept that in addition to their favorable effect on the lipid profile, statins can also exert an array of antiinflammatory and immunomodulatory actions. 

Isotachis lyallii Mitt, is a liverwort that occurs on both the north and south islands of New Zealand. A study of the lipid fraction of this species collected from both islands revealed different secondary metabolite profiles involving sesquiterpenes and aromatic esters (Asakawa et al., 1997). The sesquiterpene array consisted of... 

Figure 3.3 Molecular structure of G-protein-coupled receptors. In (a) the electron density map of bovine rhodopsin is shown as obtained by cryoelectron microscopy of two-dimensional arrays of receptors embedded in lipid membrane. The electron densities show seven peaks reflecting the seven a-helices which are predicted to cross the cell membrane. In (b) is shown a helical-wheel diagram of the receptor orientated according to the electron density map shown in (a). The diagram is seen as the receptor would be viewed from outside the cell membrane. The agonist binding pocket is illustrated by the hatched region between TM3, TM5 and TM6. (From Schertler et al. 1993 and Baldwin 1993, reproduced from Schwartz 1996). Reprinted with permission from Textbook of Receptor Pharmacology. Eds Foreman, JC and Johansen, T. Copyright CRC Press, Boca Raton, Florida...

Figure 13.2 Fluorescence micrographs of DOPC multi-layer patterns fabricated by dip-pen nanolithography, (a) An array of 25 contiguous line features. Red color is from doped rhodamine-labeled lipid, (b) A higher magnification of the region highlighted by the white square in (a), (c) Two-component patterns containing two different dyes. Green color is from doped NBD-labeled lipid.

Majd, S. and Mayer, M. (2005) Hydrogel stamping of arrays of supported lipid bilayers with various lipid compositions for the screening of drug-membrane and protein-membrane interactions. Angew. Chem. Int. Ed., 44, 6697-6700. 

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