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Fats, Fatty Acids, and Lipids
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Phospholipids are similar to triglycerides, but one end carbon of the glycerol backbone has a phosphate group instead of a fatty acid (phosphatide). The phosphate group is usually bound to one of the following: choline, ethanolamine, serine, or inositol to form a phospholipid. Sterols are hydrocarbon ring structures with varying amounts of unsaturation. Steroids (polyunsaturated sterols) have rigid, planar structures. Many modifications of sterols and steroids are encountered, with esterification, hydroxylation, oxidation, and conjugation being more frequently observed. Common sterols and steroids are cholesterol, p-sitosterol, bile acids, estrogens, progestins, testosterones, corticosteroids, and mineralosteroids. Dolichols are long-chain alcohols used in carbohydrate transport and metabolism in cells. Quinones are exemplified by coenzyme Q10, an extremely important link in the conversion of foodstuffs into cellular energy. Quinones possess substituted rings, usually with hydrocarbon side chains, and are present inside of cell organelle membranes.
α-Mannosidosis (β-Mannosidosis)
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
Affected patients, and those with aspartylglucosaminuria, have been reported to have elevated levels of dolichol in the serum [55, 56]. This could prove useful in diagnosis. It may reflect the fact that complex glycoproteins are synthesized by the transfer of oligosaccharide precursor from dolichol to the asparagine of the peptide.
Ocular Manifestations of Neuronal Ceroid Lipofuscinoses
Published in Seminars in Ophthalmology, 2021
Rohan Bir Singh, Prakash Gupta, Akash Kartik, Naba Farooqui, Sachi Singhal, Sukhman Shergill, Kanwar Partap Singh, Aniruddha Agarwal
Massive neuronal loss and accumulation of intracellular acidic sphingomyelinase are the predominant features in all patients. Moreover, genetic heterogeneity adds to this challenge. Urine sediment dolichol levels are elevated in both types – it’s a nonspecific but helpful finding. Neuroradiological findings in CLN-4 disease: include parieto-occipital cortical atrophy, cerebellar atrophy, hyperintense periventricular areas; and periventricular thinning and enlargement.98–100A cortical layer-specific loss of neurons has been described in layers 2 and 3 for CLN-4 disease, and EEG in the patients reveals a slow background, polyphasic spikes, and slow-wave changes.7,100,101 These changes can most reliably be confirmed by invasive brain biopsy.96 The diagnosis remains neuropathological, and despite the rarity of disease and absence of noninvasive diagnostic techniques, several criteria and guidelines are being developed by experts.89
Low-glycosylated forms of both FSH and LH play major roles in the natural ovarian stimulation
Published in Upsala Journal of Medical Sciences, 2018
How is the pituitary production of low- versus fully glycosylated gonadotrophins regulated? The N-glycosylation occurs in the rough endoplasmic reticulum (ER) [see schematic drawing in Figure 7 with nomenclature, pathways, and design from refs. (22–25)]. Dolichol is a special lipid that works as a carrier of the oligosaccharide precursor. The assembly of the dolichol oligosaccharide precursor is formed on the cytoplasmic side of the ER membrane. A flippase then flips the dolichol oligosaccharide precursor across the membrane bilayer to the lumen side of the ER, where enzymes complete the oligosaccharide structure. A protein complex in the ER membrane, termed oligosaccharyltransferase (OST), transfers the oligosaccharide precursor to a gamma amino group of asparagine (-Asn-X-Thr/Ser) on nascently translated proteins.
Comprehensive manipulation of glycosylation profiles across development scales
Published in mAbs, 2019
Sven Loebrich, Elisa Clark, Kristina Ladd, Stefani Takahashi, Anna Brousseau, Seth Kitchener, Robert Herbst, Thomas Ryll
Numerous media additives have been used to modulate glycosylation structures, including galactose, glucosamine,15,19 N-acetyl glucosamine (GlucNAc), uridine, mannose, N-acetyl neuraminic acid (NeuNAc),16 N-acetyl mannosamine (ManNAc),17,18 ammonia,19 manganese,20 dolichol phosphate,21 cytidine,22 and glycerol.23,36 Similarly, a variety of enzyme inhibitors has been exploited.24–27 In our study, we tested 10 commonly used media additives and characterized their effect on the glycosylation profile of different IgG1 molecules. We found that feeding of 12.5 mM glucosamine led to dramatic decreases in galactosylated species, in line with observations by others.16,37 For example, Hills and colleagues saw a 57% drop in galactosylation in GS-NS0 cells in response to 10 mM glucosamine.15 The same concentration has also been reported to reduce the degree of sialylation,17,19 (reviewed in ref. 1), in line with the notion that the addition of sialic acid residues occurs on terminally galactosylated glycoforms (reviewed in refs. 1,10, and 11). The suppression of galactosylated species in response to glucosamine feeding is widely believed to stem from competition for UTP in the formation of UDP-GlcNAc, which hampers generation of UDP-Gal.38 In addition, competitive inhibition of the UDP-galactose transporter may play a role. Both mechanisms result in limited availability of activated galactose in the lumen of the Golgi cisternae. We observed a mild retardation of cell growth in response to glucosamine feeding, a phenomenon that has been described by others 37 and is believed to result either from depletion of the cytosolic acetyl-CoA pool as a consequence of the acetylation of glucosamine to GlcNAc,37 or from inhibition of glucose uptake.19 In addition, we observed an increase in Man5 species in response to glucosamine supplementation. Others have reported a decrease in high mannose species after glucosamine feeding, albeit in Madin-Darby canine kidney cells,39 and in NS0 cells15 (reviewed in ref 10).