Lipids adaptation

Lampe, M.F., et al. 1998. Killing of Chlamydia trachomatis by novel antimicrobial lipids adapted from compounds in human breast milk. Antimicrob Agents Chemother 42 1239. 

Wodtke, E. (1978). Lipid adaptation in liver mitochondrial membranes of carp acclimated to different environmental temperatures. Phospholipid composition, fatty acid pattern and cholesterol content. Biochimica etBiophysicaActa 529,280-291. 

TABLE 3. Human Stratum Corneum Lipid Composition from Different Sources (wt% of Totai Extracted Stratum Corneum Lipid), Adapted from Wertz and Norien, 2003. 

Concentration of particular lipid types by this phase separation can cause the formation of non-bilayer structures. Lipid adaptations to environmental temperatures are discussed in section 8.2. 

Some polymyxins are sold for second-line systemic therapy. Polymyxin B sulfate and colistimethate sodium can be used for intravenous, intramuscular, or intrathecal administration, especially for Pseudomonas aerupinosa mP QXiosis, but also for most other gram-negative organisms, such as those resistant to first-line antibiotics. Nephrotoxicity and various neurotoxicities are common in parenteral, but not in topical, use. Resistance to polymyxins develops slowly, involves mutation and, at least in some bacteria, adaptation, a poorly understood type of resistance that is rapidly lost on transfer to a medium free of polymyxin. Resistance can involve changes in the proteins, the lipopolysaccharides, and lipids of the outer membrane of the cell (52). Polymyxin and colistin show complete cross-resistance. 

Figure 13.2 Activated G protein receptors, here represented as seven red transmembrane helices, catalyze the exchange of GTP for GDP on the Gapy trimer. The then separated Ga-GTP and Gpy molecules activate various effector molecules. The receptor is embedded in the membrane, and Ga, Gpy and G py are attached to the membrane by lipid anchors, and they all therefore move in two dimensions. (Adapted from D. Clapham, Nature 379 297-299, 1996.)...

A molecular variation of plasma membrane has been reported by Puccia et al. Reduction of total lipids (XL) content and significant variations of triglyceride (TG) and phospholipids (PL) fractions were observed as a consequence of exposure of C. intestinalis ovaries to TBTCl solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell-adaptive standing mechanism toward the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUPA), important in the synthesis of compounds such as prostaglandin which are present in the ovary in a stress situation, was probably a consequence of a defense mechanism to the stress provoked by the presence of TBTCl. 

The nature of the diet sets the basic pattern of metabohsm. There is a need to process the products of digestion of dietary carbohydrate, lipid, and protein. These are mainly glucose, fatty acids and glycerol, and amino acids, respectively. In ruminants (and to a lesser extent in other herbivores), dietary cellulose is fermented by symbiotic microorganisms to short-chain fatty acids (acetic, propionic, butyric), and metabohsm in these animals is adapted to use these fatty acids as major substrates. All the products of digestion are metabohzed to a common product, acetyl-CoA, which is then oxidized by the citric acid cycle (Figure 15-1). 

Nichols DS, MR Miller, NW Davies, A Goodchild, M Raferty, R Caviccholi (2004) Cold adaptation in the Antarctic arch eon Methanococcoides burtonii involves membrane lipid unsaturation. J Bacterial 186 8508-8515. 

Figure 13.3 (a-c) Trajectories of the diffusion motion of a gold nanoparticle probe on a planar lipid membrane, (d) Mean-square displacement plots forthe diffusion shown in (a-c). Adapted from Ref [31] with permission. 

Figure 13.5 (a) Fluorescence micrograph of the self-spreading lipid bilayer doped with a dye molecule. The lipid bilayer spread on an oxidized silicon wafer from a deposited lipid aggregate illustrated on the left, (b) A schematic drawing of the selfspreading lipid bilayer from the lipid aggregate. Adapted from Ref [48] with permission. 

Figure 13.7 (a) The self-spreading distance and (b) velocity of egg-PC lipid bilayer in NaCI aqueous solutions with different concentrations, (x) 100mM, (0) 10mM, and ( ) 1 mM. Adapted from Ref [53] with permission. 

Alessio, H.M. and Goldfarb, A.H. (1988). Lipid peroxidation and scavenger enzymes during exercise adaptive response to training. J. Appi. Physiol. 64, 1333-1336. 

One of the key parameters for correlating molecular structure and chemical properties with bioavailability has been transcorneal flux or, alternatively, the corneal permeability coefficient. The epithelium has been modeled as a lipid barrier (possibly with a limited number of aqueous pores that, for this physical model, serve as the equivalent of the extracellular space in a more physiological description) and the stroma as an aqueous barrier (Fig. 11). The endothelium is very thin and porous compared with the epithelium [189] and often has been ignored in the analysis, although mathematically it can be included as part of the lipid barrier. Diffusion through bilayer membranes of various structures has been modeled for some time [202] and adapted to ophthalmic applications more recently [203,204]. For a series of molecules of similar size, it was shown that the permeability increases with octa-nol/water distribution (or partition) coefficient until a plateau is reached. Modeling of this type of data has led to the earlier statement that drugs need to be both... 

Unsaturations of lipids play a key role in lipid homeostasis, where organisms adapt to temperature variations of the environment. Plants and animals maintain physiological functions by reversibly altering the composition and conformation of lipid molecules of the cell membrane. To achieve this, they extensively and elegantly use the unsaturations (double bonds) present in their side chains. This is the process by which cell membranes adjust their flexibility (fluidity) of the bilayer and adapt themselves to perturbations in temperature, pressure, and other variations in the natural environment [11-14]. They remain indispensable for the poikilothermism exhibited by fishes, invertebrates, and amphibians [15, 16]. Commercially,... 

Sinensky, M. (1974) Homeoviscous adaptation - a homeostatic process thatregulates the viscosity of membrane lipids in Escherichia coli. Proceedings of the National Academy of Sciences of the, 71 (2), 522-525. 

In conclusion, this analysis shows that QSAR studies have to be adapted to the special situation of P-gp, and that lipid partitioning and receptor binding must be addressed separately in order to reach a high predictive value. 

Figure 2.15 APCI (+) mass spectrum of the lipid extract obtained from a ceramic vessel recovered from the thirteenth century church of Sant Antimo in Piombino (Central Italy) (a). TheAPCI MS/MS spectrum obtained by selecting ions at m/z 315 (b). The latter made it possible to determine that ions at m/z 315 are due to protonated 7 oxodehydroabietic acid. (Adapted from ref. [29])...

FIGURE 25.1 Mechanism of the inhibitory effect of nitric oxide on lipid peroxidation. (Adapted from VB O Donnell, BA Freeman. Circ Res 88 12-21, 2001.)... 

Ion channels are macromolecular complexes that form aqueous pores in the lipid membrane. We have learned much about ion channel function from voltage clamp and patch clamp studies on channels still imbedded in native cell membranes [1-6, 8]. A diversity of channel types was discovered in the different cells in the body, where the repertoire of functioning channels is adapted to the special roles each cell plays [5]. The principal voltage-gated ones are the Na+, K+ and Ca2+ channels, and most of these are opened by membrane depolarizations. Figure 6-5A summarizes the major functional properties of a voltage-gated... 

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