Showing papers by "John L. Harwood published in 2007"

The Lipid Handbook with CD-ROM

Abstract: Fatty Acid and Lipid Structure Fatty acid structure Lipid structure Occurrence and Characterization of Oils and Fats Introduction Major oils from plant sources Minor oils from plant sources Milk fats, animal depot fats, and fish oils Waxes Egg lipids Milk lipids Liver and other tissue lipids Cereal lipids Leaf lipids Algal lipids Fungal lipids Bacterial lipids Lipids of viruses Production and Refining of Oils and Fats Introduction Production of animal oils and fats Production of vegetable oils and fats Degumming of oils and fats Alkali refining of oils and fats Soap stock and by-product treatments Bleaching of oils and fats Dewaxing of oils Vacuum stripping of oils and fats HACCP for oils and fats supply chains Modification Processes and Food Uses Introduction Hydrogenation Interesterification. Fractionation Food grade emulsifiers Food uses of oils and fats Synthesis Unsaturated fatty acid synthesis via acetylene Fatty acid synthesis by the Wittig reaction Isotopically labelled fatty acids Synthesis of acylglycerols Fullerene lipids Glycerophospholipids Sphingolipids Glycosylglycerides Bulk separation procedures Analysis Introduction Requirements stemming from quality control and process investigation Some selected analytical methods Chromatographic analysis of lipids Nuclear magnetic resonance spectroscopy Physical Properties: Structural and Physical Characteristics Introduction Crystallisation and melting Phase behavior Lipid/water interactions Interaction between lipids and proteins Biological membranes Chemical Properties Autoxidation and photo-oxidation Enzymatic oxidation Epoxidation, hydroxylation and oxidative fission Halogenation and halohydrins Oxymercuration Metathesis Stereomutation Double-bond migration and cyclization Cyclization Dimerization Chain branching and extension Hydrolysis, alcoholysis, esterification, and interesterification Acid chlorides, anhydrides, and ketene dimers Peroxy acids and related compounds Nitrogen-containing compounds Other reactions of the carboxyl group Oleochemical carbonates Guerbet compounds Nonfood Uses of Oils and Fats Introduction Basic oleochemicals Surfactants Lipids as formulating tools in skin care and cosmetics Lubricants Biofuels Surface coatings and inks Castor oil products Lipid Metabolism Fatty acids Glycerophospholipids Glyceride metabolism Glycosylglycerides Sphingolipids Lipids as signaling molecules Sterol esters Control mechanisms Nutritional, Medical and Agricultural Aspects of Lipids Human dietary requirements Lipids and cardiovascular disease Clinical aspects of lipids with emphasis on cardiovascular disease and dyslipaemia Skin lipids and medical implications Sphingolipidoses Other disorders of lipid metabolism Pulmonary surfactant (lung surfactant) Agricultural aspects

Membrane Regulation of the Stress Response from Prokaryotic Models to Mammalian Cells

Abstract: "Membrane regulation" of stress responses in various systems is widely studied. In poikilotherms, membrane rigidification could be the first reaction to cold perception: reducing membrane fluidity of membranes at physiological temperatures is coupled with enhanced cold inducibility of a number of genes, including desaturases (see J.L. Harwood's article in this Proceedings volume). A similar role of changes in membrane physical state in heat (oxidative stress, etc.) sensing- and signaling gained support recently from prokaryotes to mammalian cells. Stress-induced remodeling of membrane lipids could influence generation, transduction, and deactivation of stress signals, either through global effects on the fluidity of the membrane matrix, or by specific interactions of boundary (or raft) lipids with receptor proteins, lipases, ion channels, etc. Our data point to membranes not only as targets of stress, but also as sensors in activating a stress response.

Temperature stress: reacting and adapting: lessons from poikilotherms.

Abstract: Acanthamoeba castellanii (A. castellanii) is a common soil- or water-borne protozoon that feeds on bacteria by phagocytosis. A. castellanii can grow between 4 and 32 degrees C and has to adapt quickly to chilling in order to survive. We have identified a Delta12-fatty acid desaturase as key to low temperature adaptation. The activity of this enzyme is mainly increased through gene expression and new protein synthesis. Interestingly, the activity can also be altered independently by dissolved oxygen levels. In addition, we have identified a gene for the Delta12-desaturase, which, when expressed in yeast, catalyses Delta15-desaturation also. Moreover, it is also capable of producing very unusual n-1 polyunsaturated products.

Abnormal surfactant composition and activity in severe bronchiolitis.

Abstract: A prospective study of infants under 1 y of age, ventilated for severe viral bronchiolitis, was carried out in four paediatric intensive care units in order to study surfactant activity and composition in this condition. Lung lavage fluid from 24 infants with bronchiolitis, 19 with bronchiolitis and sepsis or cardiac failure and 12 controls were analysed by the “click test” for surfactant activity and for phospholipids. Surfactant activity was present in all controls, but in only 2 of the 24 infants with bronchiolitis alone. The presence of phosphatidylglycerol correlated perfectly with the click test, suggesting that reduced activity is due to changes in surfactant lipid composition. In those with bronchiolitis plus coexisting disease, surfactant activity and phosphatidylglycerol were absent in only half. Surfactant activity and phosphatidylglycerol re-appeared by extubation. Severe viral bronchiolitis is associated with an absence of surfactant activity and PG, which resolves by clinical recovery. Infants with coexisting conditions are not always surfactant deficient. Surfactant administration is likely to be beneficial, but requires a selective approach. □Bronchiolitis, lung surfactant, phosphatidylglycerol

Complex lipid biosynthesis and its manipulation in plants

Abstract: In all living organisms lipids play several roles and, according to their structures, can be divided into two main groups: the non-polar lipids (acylglycerols, sterols, free fatty acids, wax and steryl esters) and polar lipids (phosphoglycerides, glycosylglycerides, and sphingolipids). Triacylglycerols act as compact, easily metabolised and non-hydrated energy stores. They are important storage products especially in plants producing oilseeds and in oily fruits such as avocado, olive and oil palm. Waxes are commonly extracellular components such as surface coverings, which function both to reduce water loss and to protect plants from noxious environmental conditions. They also act as an energy store in jojoba. Polar lipids and sterols are important structural components of cell membranes with many diverse functions. The membrane lipids act as permeability barriers for cells and organelles (Gurr et al. 2002). They provide the matrix for assembly and function of a wide variety of catalytic processes as well as directly participating in metabolism and in a multitude of membrane fusion events. Moreover, the membrane lipids actively influence the functional properties of membrane-associated processes (Gurr et al. 2002). In additional to a structural role, lipids act as key intermediates

Can the stress protein response be controlled by 'membrane-lipid

Abstract: In addition to high temperature, other stresses andclinical conditions such as cancer and diabetes can leadto the alteration of heat-shock protein (HSP) levels incells. Moreover, HSPs can associate with either specificlipids or with areas of special membrane topology (suchas lipid rafts), and changes in the physical state ofcellular membranes can alter hsp gene expression. Wepropose that membrane microheterogeneity is import-ant for regulating the HSP response. In support of thishypothesis, when particular membrane intercalatingcompounds are used to alter membrane properties,the simultaneous normalization of dysregulated expres-sion of HSPs causes beneficial responses to diseasestates. Therefore, these compounds (such as hydroxy-lamine derivatives) have the potential to become a newclass of pharmaceuticals for use in ‘membrane-lipidtherapy’.Denaturation of proteins is not the only ‘heat-shock’signalHeat-shock (HS) proteins (HSPs; see Glossary) haveseveral properties that help cells and tissues respond tostress: they have anti-oxidant effects and anti-inflamma-tory action, aid in the folding and re-folding proteins,protect membranes from damage and inhibit apoptosis[1].Althoughit isaccepted thatenhancedhspgene expres-sion following various stimuli is basically regulated by HSfactors (HSFs), many details are still unknown. In theclassic model, the common primary signal is an increaseindenaturedproteinsduringthermalstress[2].Duringnon-stress conditions, HSPs are expressed at low levels andmaintainthemonomerHSFsinaninactive,repressedstate.De-repression of HSFs occurs as a result of the titration ofHSPs away from the HSFs by the stress-induced formationof denatured proteins. HSF then translocates into thenucleus, trimerizes, undergoes hyperphosphorylation andbindstohspgenepromoters,thusleadingtothesubsequentexpression of their proteins.However, this dogma does not fit many specificsituations. For example, in Saccharomyces cerevisiae, thetransient activation of HSF upon heat shock is indepen-dent of expression levels of hsp genes [3]. The mechanismresponsible for setting the activation temperature for HSFin yeast can ‘recalibrate’ to match the growth conditions,but it is not influenced by HSPs. Moreover, the HSresponses (HSRs) in Drosophila and mammalian cellsOpinion