Lipid consequences

In summary, the binding of oxLDL and/or lipids to several SC receptors (SRAI/II, CD36, CD68) has been clearly demonstrated. Most of other receptors may potentially bind oxLDL or lipids. Consequently, the cellular internalization of oxidized lipids by the SC receptor pathways may be involved in the biological effect of oxLDL, such as apoptosis induction. As a likely major ligand and because of their oxidized lipid contents, oxLDL may have many putative effects on different cells, such as alteration of cell signaling and gene expression. 

Answer When the temperature drops, the fluidity of a membrane decreases. This is caused by a decrease in the rate of diffusion of lipids. Consequently, all processes depending on diffusion, such as the lateral diffusion experiment shown in Figure 11-17, would slow down. 

The commonly encountered OP anci-ChE agents are, with some exceptions (e.g., echothlophate), highly soluble in lipids. Consequently, they are rapidly and effectively absorbed when administered by almost any route, including the gastrointestinal tract, the skin and mucous membranes after contact with the liquid form, and the lungs after inhalation of vapors, finely dispersed dust, or aerosols. Most OP compounds are excreted almost entirely as metabolites In urine. Between the time of absorption and excretion, there are varied periods during which the original compound or its metabolites remain bound to proteins in Che blood and tissues. 

Biological membranes are essentially lipid consequently, the rate at which drug molecules cross these barriers is dictated primarily by their lipid solubility. Molecular size and shape and the solubility at the site of absorption also directly affect the absorption of drugs. The other important factor that determines the ability of a drug to cross these biological barriers is the degree of ionization. 

It was demonstrated that the procedures, as expected, led to differing lipid yields. They differ also, however, in their selectivity with regard to certain lipid classes (neutral lipids, glycolipids, polar lipids). Consequently, only the Bligh and Dryer method delivers maximum extraction for aU lipid classes. ... 

One of the important consequences of neuronal stimulation is increased neuronal aerobic metabolism which produces reactive oxygen species (ROS). ROS can oxidize several biomoiecules (carbohydrates, DNA, lipids, and proteins). Thus, even oxygen, which is essential for aerobic life, may be potentially toxic to cells. Addition of one electron to molecular oxygen (O,) generates a free radical [O2)) the superoxide anion. This is converted through activation of an enzyme, superoxide dismurase, to hydrogen peroxide (H-iO,), which is, in turn, the source of the hydroxyl radical (OH). Usually catalase... 

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. 

Several authors, beginning with Kmeger and Sullivan (1984), have noted a smaller 8 C fractionation between collagen and apatite (A,p.co) in carnivores as compared to herbivores. These authors presented a model to accoimt for this, and the observation was confirmed in studies by Lee-Thorp and van der Merwe (1991) of populations of carnivores and herbivores that differed widely in their intake of C3- and C4-based foods. Here 1 shall show how this effect might be accounted for as a consequence of partial blocking of AA synthesis from lipids. 

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