Introduction
Margit Hamosh in Lingual and Gastric Lipases: Their Role in Fat Digestion, 2020
In general terms the digestion and absorption of fat involves essentially the transport of water-insoluble molecules from one water phase, the lumen of the gastrointestinal tract, to another water phase, the lymph and plasma. This chapter aims to start with definitions of the terms lipid and lipase. Triglycerides (neutral fat) are the most abundant lipids in animal tissue and serve as an important energy source. Glycerides and non-phosphorus-containing lipids which result from the esterification of glycerol and fatty acids. Phospholipids, phosphorus-containing lipid compounds, may be subdivided into three classes: derivatives of glycerol-3-phosphate (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, and phosphatidyl inositol), sphingosine, and the glycoplipids. Fatty acids of animal origin are usually unbranched, monocarboxylic acids containing an even number of carbon atoms, varying from 2 to 24 in chain length. Storage lipid contains higher amounts of saturated fatty acids than do structural lipids.
Investigation of membrane lipids
John M. Graham, Joan A. Higgins in Membrane Analysis, 2020
The basic principles involved in probing the transverse distribution of membrane lipids are simple. Lipids that are available for modification by probes are in the outer leaflet of the membrane bilayer, and those only available in permeabilized vesicles are in the inner leaflet. The experimental design and controls are similar to those for determining the orientation of membrane proteins. The chemical probes available for reaction with membrane phospholipids are largely restricted to those that react with amino groups in phosphatidylethanolamine and phosphatidylserine. Preliminary experiments should be carried out to determine the amount of isotope required to obtain sufficient incorporation into the phospholipids of interest. With few exceptions, membrane phospholipids are synthesized in the endoplasmic reticulum by enzymes located at the cytosolic side of this membrane. Nitrobenzoxadiazole-labeled lipids are incorporated into liposomes and spontaneously transfer into the plasma membrane of cells.
Phospholipid Organization in Cellular Membranes
José M. Mato in Phospholipid Metabolism in Cellular Signaling, 2018
In the fluid mosaic model, the prevailing model for membrane structure, phospholipids form a bilayer into which proteins are partially or fully immersed. Phospholipids, as proteins, are not, however, static molecules and are able to perform various types of movements in the bilayer. Individual species of biological membrane phospholipids adopt in their liquid crystalline state one of three structures: micellar, hexagonal, or bilayer. A simple shape concept model has been proposed to predict the type of structure that phospholipids will adopt upon hydration. In the fluid state, individual phospholipid molecules undergo rapid rotational diffusion around the axis of the phospholipid and rocking motions. In addition, phospholipids can migrate laterally in the plane of the lipid crystalline bilayer. Enhanced transbilayer mobility of the four major phospholipids are phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin has been observed using electron spin resonance in Plasmodium knowlesi -infected monkey erythrocytes.
Antibodies to Oxidized Low-Density Lipoprotein, Cardiolipin, and Phosphatidyl Serine Fail to Predict the Risk of Preeclampsia
Published in Hypertension in Pregnancy, 1996
Tapio Kurki, Kirsi Ailus, Timo Palosuo, Olavi Ylikorkala
Objective: In view of the data that high levels of antibodies to oxidized low-density lipoprotein (LDL), cardiolipin, and phosphatidyl serine are present in plasma of women with established preeclampsia, we studied whether the risk of preeclampsia could be predicted by these antibodies. Methods: In our prospective trial, blood samples were drawn from 722 healthy nulliparous women at the first prenatal checkup between 10 and 17 gestational weeks. Twenty of them (2.8%) developed established preeclampsia (blood pressure elevation > 140/100 mm Hg and proteinuria 0.3-8.3 g/24 h). As a control group we studied 42 women who remained normotensive during pregnancy and delivery, and postpartum. Results: The levels of antibodies to oxidized LDL, cardiolipin, or phosphatidyl serine in women later developing preeclampsia did not differ from levels in women who remained normotensive. Conclusion: We conclude that antibodies to oxidized low-density lipoprotein, cardiolipin, and phosphatidyl serine fail to predict the risk of preeclampsia.
Blockade of Tim-3 binding to phosphatidylserine and CEACAM1 is a shared feature of anti-Tim-3 antibodies that have functional efficacy
Published in OncoImmunology, 2018
Catherine A. Sabatos-Peyton, James Nevin, Ansgar Brock, John D. Venable, Dewar J. Tan, Nasim Kassam, Fangmin Xu, John Taraszka, Luke Wesemann, Thomas Pertel, Nandini Acharya, Max Klapholz, Yassaman Etminan, Xiaomo Jiang, Yu-Hwa Huang, Richard S. Blumberg, Vijay K. Kuchroo, Ana C. Anderson
Both in vivo data in preclinical cancer models and in vitro data with T cells from patients with advanced cancer support a role for Tim-3 blockade in promoting effective anti-tumor immunity. Consequently, there is considerable interest in the clinical development of antibody-based therapeutics that target Tim-3 for cancer immunotherapy. A challenge to this clinical development is the fact that several ligands for Tim-3 have been identified: galectin-9, phosphatidylserine, HMGB1, and most recently, CEACAM1. These observations raise the important question of which of these multiple receptor:ligand relationships must be blocked by an anti-Tim-3 antibody in order to achieve therapeutic efficacy. Here, we have examined the properties of anti-murine and anti-human Tim-3 antibodies that have shown functional efficacy and find that all antibodies bind to Tim-3 in a manner that interferes with Tim-3 binding to both phosphatidylserine and CEACAM1. Our data have implications for the understanding of Tim-3 biology and for the screening of anti-Tim-3 antibody candidates that will have functional properties in vivo.
Clinical outcomes of magnetic activated sperm sorting in infertile men candidate for ICSI
Published in Human Fertility, 2019
Niloofar Ziarati, Marziyeh Tavalaee, Mehrnoosh Bahadorani, Mohammad Hossein Nasr Esfahani
Magnetic activated cell sorting (MACS) with annexin V microbeads deselected apoptotic sperm with externalized phosphatidylserine (PS) residues on their surface and decrease chance of such sperm to be inseminated. Therefore, the aim of this study was to evaluate efficiency of MACS procedure in a prospective randomized trial. Sixty-two semen samples were allocated into two groups and processed according to: (i) a combination of MACS with density gradient centrifugation (MACS–DGC) as study group (N = 29); and (ii) DGC alone as a control group (N = 33). Fertilization, embryo quality, pregnancy and implantation rates were compared between the two groups. Although, no significant difference was observed in fertilization rates between the two groups, the percentage of high-quality embryos, pregnancy and implantation rates was significantly higher in the MACS–DGC group compared to DGC alone. Therefore, MACS may help to select the most fertile sperm and improve clinical outcomes of intra-cytoplasmic sperm injection (ICSI).