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Polyunsaturated fatty acids (PUFAs) are critical to nervous system function and structure, but their rates of incorporation from plasma into brain have not been evaluated. In the adult rat, calculations based on our model show that at least 3;-5% of esterified brain arachidonic acid (AA) and 2;-8% of esterified brain docosahexaenoic acid (DHA) are replaced daily by unesterified PUFAs in plasma. These rates, when related to unlabeled brain PUFA composition, give half-lives of 1-2 weeks for plasma-brain exchange of AA and DHA. In the human brain, the arachidonate replacement rate is 0.3% per day. Although unesterified plasma PUFA concentrations are low, their rates of incorporation into brain are sufficient to compensate for metabolic and efflux losses, so that PUFA transport from plasma into brain as a component of a lipoprotein is unnecessary. Dietary supplementation, by altering plasma unesterified PUFA concentrations, can regulate brain PUFA content and may help to treat brain diseases involving PUFA imbalance.

Publisher Summary Lipoprotein (Lp) [a] is a lipoprotein whose plasma concentration is highly correlated with cardiovascular disease. Electrophoretic methods have been used widely for many years for qualitative detection and quantitative measurement of plasma lipoproteins, especially Lp[a]. The movement of a lipoprotein or apoprotein in an electrophoretic field is determined by several physiochemical properties, such as charge, size, shape, and composition. When electrophoretic migration is used with immunochemical reaction, the combined properties can be used for positive identification of specific migrating species. However, migration and immunoreactivity may be significantly altered by variations in specific structural features. In case of apolipoprotein (apo) [a], variations in the number of kringle repeats, carbohydrate content, and disulfide pairing can have profound effects. For Lp[a], lipid content and association with other apoB-containing lipoproreins can be important determinants of migratory and immunoreactive behavior. In this chapter, the topic of electrophoretic methods for quantification has been expanded beyond concentration determination to include other properties of apo[a] or Lp[a] amenable to measurement. These include apo[a] polymorph classification and phenotyping for individual and population analyses, molecular weight (Mr) determination of apo[a] polymorphs, and calculation of relative electrophoretic mobility. Investigations that combine various aspects of these analytical electrophoretic methods expand the opportunities for assessing structure and function relationships. Some of the features of apo[a] and Lp[a] and how these impact on the determinations are briefly discussed in this chapter.

A sensitive latex immunoassay for human serum lipoprotein Lp(a+) is based on direct agglutination by Lp(a+) of latex particles coated with specific antibody. The agglutination is quantified by turbidimetry using a photometer at 360 nm. The stabilization of antibody-coated latex particles by bovine serum albumin occurs under well-defined conditions (pH, concentration of bovine serum albumin, and antibody loading of latex particles). The standard curve of serum lipoprotein Lp(a+) ranges from 0.05 to 1.15 mg/l. Inter- and intra-assay coefficients of variation were less than 8% and 3%, respectively. Results were well correlated with those obtained by electroimmunodiffusion (r = 0.98, n = 108).

Publisher Summary This chapter discusses the methods for altering the synthesis of phosphatidylinositol and phosphatidylglycerol by type II pneumonocytes. Type II pneumonocytes of the alveolar epithelium produce a lipoprotein, lung surfactant, which is essential for normal respiration. Glycerophospholipids comprise more than 80% of the dry weight of surfactant, and the glycerophospholipid composition of surfactant has two unusual features. First, phosphatidylcholine, which is the most abundant and principal surface-active glycerophospholipid of surfactant, consists largely of disaturated molecular species. Second, phosphatidylglycerol, which is quantitatively a minor lipid in most mammalian cells, is the second most abundant glycerophospholipid of surfactant. Surfactant produced by immature fetal lungs, however, contains phosphatidylinositol in place of phosphatidylglycerol. Type II pneumonocytes have been isolated from the lungs of several species and offer some advantages as experimental models in the investigations of the regulation of glycerophospholipid metabolism. The chapter describes the isolation of type II pneumonocytes.

Publisher Summary The chapter summarizes the information concerning early virus-cell interaction published during the past decade. It also describes the general problems concerning attachment, penetration, and uncoating. Animal viruses are usually divided into two classes—those with a lipoprotein envelope and those without. The former class contains detectable amounts of lipid while the latter class does not. It is believed that the early virus-cell interaction for these two classes of viruses is different. An attractive role for viral envelope proteins is to effect attachment and penetration of the virus through the cell plasma membrane, thus providing efficient translocation of virus genetic material to the host cell. Surprisingly, nonenveloped viruses often follow a similar pathway in gaining entry into the cell suggesting that the functions of the virus envelope is superseded by surface proteins of these viruses. The complexity of the subject and the controversy surrounding it are presented fully and the gaps in the knowledge and ignorance of many points concerning early virus-cell interaction are indicated.