Transport, in plasmas

Phospholipids. Phospholipids, components of every cell membrane, are active determinants of membrane permeabiUty. They are sources of energy, components of certain enzyme systems, and involved in Hpid transport in plasma. Because of their polar nature, phosphoUpids can act as emulsifying agents (42). The stmcture of most phosphoUpids resembles that of triglycerides except that one fatty acid radical has been replaced by a radical derived from phosphoric acid and a nitrogen base, eg, choline or serine. 

Rye K-A et al Overview of plasma lipid transport. In Plasma Lipids and Their Role in Disease. Barter PJ, Rye K-A (editors). Harwood Academic Publishers, 1999. 

P. Askerlund and C. Larsson, Transmembrane electron transport in plasma membrane vesicles loaded with an NADH-generating system or ascorbate. Plant Phy-.i-iol. 96 1178 (1991). 

Transferrin Iron transport in plasma and into cells hpx mice (Huggenvik et al, 1989 Bernstein, 1987 Craven et al, 1987 Goya et al, 1972) Hypotransferinemia (Goya et al., 1972) microcytic anaemia increased iron absorption parenchymal iron overload... 

The recovery of neurotransmitters from synaptic clefts and their storage in cytoplasmic vesicles is accomplished by the tandem actions of the secondary transporters in plasma and vesicular membranes 84 Packaging neurotransmitters into presynaptic vesicles is mediated by proton-coupled antiporters 86... 

SODIUM-DEPENDENT GLUTAMINE TRANSPORTERS IN PLASMA MEMBRANES MEDIATE THE TRANSFER OF GLUTAMINE FROM ASTROCYTES TO NEURONS 287... 

This receptor-mediated endocytotic pathway has been especially well studied in the uptake of iron from blood plasma. Iron, because of its very low-solubility product (< 1(T17 at pH 7.4), is transported in plasma bound to the iron-binding protein transferrin. Two Fe3+ ions bind to each transferrin molecule. Entry into... 

Contrary to popular belief, ceruloplasmin5, the principal copper-containing protein in plasma, ceruloplasmin, is not involved in copper transport. This is clearly underlined by the clinical observation that patients with aceruloplasminaemia (i.e. lacking ceruloplasmin in their blood) have perfectly normal copper metabolism and homeostasis. Copper is transported in plasma mostly by serum albumin with smaller amounts bound to low-molecular weight ligands like histidine. Likewise zinc is mostly transported in plasma bound to proteins (albumin and ot2-macroglobulin). 

Bilirubin derives largely from senescent erythrocyte hemoglobin [for reviews, see references (F9, G7, L6, S3, Wll)]. When transported in plasma the pigment is bound to albumin (B9, 04). Dissociation from albumin precedes rapid uptake by liver tissues (B4, Bll, B29). This uptake and the transfer of bilirubin to its sites of metabolism may be mediated by cytoplasmic binding proteins (G8, Gll, L8, M9). 

Pharmacokinetics Rapidly absorbed from the GI tract if bile salts, pancreatic lipase, protein, and dietary fat are present. Transported in blood to the liver, where it s metabolized stored in parenchymal hepatic cells, then transported in plasma as retinol, as needed. Excreted primarily in bile and, to a lesser extent, in urine. 

Eckardstein A von, Huang Y, Wu S, Funke H, Noseda G, Assmann G (1995) Reverse cholesterol transport in plasma of patients with different forms of familial HDL deficiency. Arterioscler Thromb Vase Biol 15 691-703... 

Electron micrographs of low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), chylomicrons (Chylo), and high-density lipoproteins (HDL). Lipids are transported in plasma as components of these particles. The larger particles contain a higher percentage of... 

E. J. Brandas in Dynamics of Transport in Plasmas and Charged Beams, eds. G. Maino and M. Ottaviani, World Scientific Publ. Comp., 160 (1996). 

Lever, J.E. (1977). Membrane potential and neutral amino acid transport in plasma membrane vesicles from simian virus transformed mouse fibroblasts. Biochemistry 16, 4328-4334. 

Sun, I.L., Crane, F.L., Chou, J.Y. (1986a). Modification of transmembrane electron transport in plasma membranes of simian virus 40 transformed pineal cells. Biochim. Biophys. Acta 886, 327-336. 

Hydrophobic lipids (triacylglycerols and cholesteryl esters) are virtually completely insoluble in water they are solubilized for transport in plasma by incorporation into lipoproteins. Lipoproteins are spherical complexes containing triacylglycerol (triglyceride) and cholesteryl ester surrounded by a layer containing phospholipids, unesterified cholesterol, and specific apolipoproteins. 

Application of X-Ray Spectroscopy to the Study of Energy Transport in Plasma Produced by an Ultrahigh-Intensity Laser... 

Lipoproteins are endogenous lipid carrier systems comprising a lipid core and a coat where apolipoproteins can be found. The lipid core material consists of cholesterol and other lipids (cholesterol esters, triacylglycerols and phospholipids) which are transported in plasma and other body fluids in the form of lipoproteins. The ratio of lipid to protein determines the densities of the different lipoproteins ... 

Properties known to be important in enabling molecules to pass cell membranes, whilst retaining the ability to be transported in plasma, are... 

The most commonly used index of vitamin E nutritional status is the plasma concentration of a-tocopherol because it is transported in plasma lipoproteins, it is best expressed per mole of cholesterol or per milligram of total plasma lipids (Horwitt et al., 1972 Winbauer et al., 1999). The reference range is... 

The thyroidogenic effects and corresponding biochemical mechanisms of PCBs and other OHS were recently reviewed by Brouwer et al. [44]. The selective retention of certain OH-PCB congeners in blood (Sect. 5.2.2 and 5.3.2) is concomitant with effects observed on the plasma levels of thyroid hormones. Thyroxine is transported in plasma by a protein complex consisting of TTR and retinol binding protein (RBP). Rats administered CB-77 were shown to have reduced plasma levels of both thyroxine and retinol [196]. A major metabolite of CB-77, 4-OH-3,3, 4, 5-tetrachlorobiphenyl, was identified as the active compound [40]. The same hydroxy-PCB metabolite was found to be retained in mouse fetal soft tissue [191,197]. 

Lipid-soluble hormones are transported in plasma bound to carrier proteins with only a small fi-action of the hormone being in the free or unbound state. The free hormone enters the cell via passive diffusion and binds to intracellular receptors in the cytoplasm or, more often, the nucleus (Figure 28-1). These receptors are characterized by a hormone-binding domain, a deoxyribonucleic acid (DNA)-binding domain, and an amino-terminal variable domain. Just as the interaction of protein or polypeptide hormones with cell-surface receptors changes the conformation of the receptor protein, the binding of a lipid-soluble hormone... 

Thyroid hormones T4 and T3 arrive at their target cells by transport in plasma, for the most part bound to plasma proteins (Chapter 33). The very small fraction of T4 and... 

The answer is b. (Murray, pp 627-661. Scriver, pp 3127-3164. Sack, pp 121-138. Wilson, pp 287-320.) Ferrous iron (Fe ) is the form absorbed in the intestine by ferritin, transported in plasma by transferrin, and stored in the liver in combination with ferritin or as hemosiderin. There is no known excretory pathway for iron, either in the ferric or ferrous form. For this reason, excessive iron uptake over a period of many years may cause hemochromatosis (235200), the likely diagnosis for this man. This is a condition of extensive hemosiderin deposition in the liver, myocardium, pancreas, and adrenals. The resulting symptoms include liver cirrhosis, congestive heart failure, diabetes mellitus, and changes in skin pigmentation. 

Iron is transported in plasma bound to the specific glycoprotein, transferrin, each molecule of which binds two Fe ions together with bicarbonate as an anion. A number of factors can lower serum iron independently of iron status. These include the acute pha.se response to... 

Bilirubin is derived from haem, an iron-containing protoporphyrin mainly found in haemoglobin (Fig. 2). An adult normally produces about 4.50 pmol of bilirubin daily. It is insoluble in water attd is transported in plasma almost totally... 

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