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Tasting History
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
The existence of umami as a basic taste like sweet, sour, salty, or bitter seems “new” to the American palate. Although the other four basic tastes have been identified in the West since well before the Enlightenment, the number of basic tastes has varied widely from region to region and from epoch to epoch. Aristotle identified only two tastes whereas Qing commentators noted as few as six and as many as nine. Based on the amino acids glutamic acid and the 5’-ribonucleotides guanosine monophosphate (GMP) and inosine monophosphate (IMP) umami has a distinctly East Asian pedigree as many of the foods eaten throughout the region combine these amino acids in much larger quantities than in European or American diets. In other words, Ikeda’s and the Japanese palate was trained to experience umami unlike citizens or researchers in either Europe or the United States.
Synapses
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
To gain a better understanding of second-messenger systems, it is necessary to review first some biochemistry in order to explain the structure of an important, typical second-messenger cyclic AMP (cAMP) and the guanine-derived phosphates. It should be recalled that two of the basic constituents of nucleic acids are the purine compounds adenine and guanine. When attached to the 1ʹ carbon atom of a ribose sugar molecule (Figure 6.10), they become the nucleosides adenosine and guanosine, respectively. When a single phosphate group is attached to the 5ʹ carbon atom of a ribose sugar molecule, these nucleosides become the nucleotides adenosine monophosphate (AMP) and guanosine monophosphate (GMP), respectively. However, another phosphate group can attach to the first phosphate group to give adenosine diphosphate (ADP) and guanosine diphosphate (GDP), respectively. The attachment of a third phosphate group to the second phosphate group, gives adenosine triphosphate (ATP) and guanosine triphosphate (GTP), respectively.cAMP molecule.
Biological Response Modifiers and Chemotherapeutic Agents that Alter Interleukin 2 Activities
Published in Ronald H. Goldfarb, Theresa L. Whiteside, Tumor Immunology and Cancer Therapy, 2020
William L. West, Allen R. Rhoads, Clement O. Akogyeram
Levamisole (see chemical structure in Figure 1) is known to act on cyclic nucleotide metabolism, increasing the breakdown of cyclic adenosine monophosphate (cAMP) and decreasing the breakdown of cyclic guanosine monophosphate (cGMP). Levamisole also exerts cholinergic effects, i.e., increasing cGMP levels and formation. Increased levels of cGMP are correlated with lymphocyte proliferation and augmentation of chemotactic responses after administering this drug to laboratory animals. Overall, differentiation of precursor T lymphocytes into mature effector cells, is facilitated by levamisole, although the exact mechanism of this process is unknown.
Advances in understanding of mechanisms related to increased cardiovascular risk in COPD
Published in Expert Review of Respiratory Medicine, 2021
Paola Rogliani, Beatrice Ludovica Ritondo, Rossella Laitano, Alfredo Chetta, Luigino Calzetta
BNP is a 32-amino acid vasoactive hormone synthesized and secreted by the ventricles in response to myocardial wall stress. BNP promotes vasodilation, diuresis, inhibits renin-angiotensin-aldosterone system, and sodium reabsorption in the distal tubule [109]. BNP is the endogenous ligand of the guanylate cyclase-linked natriuretic peptide receptor A (NPR-A), which causes the increase of cyclic guanosine monophosphate (cGMP) concentration in target tissues. NPR-A is extensively expressed in the CV system, kidneys, on sympathetic fibers, and a variety of pulmonary cells, mostly at the level of the respiratory epithelium and lamina propria in bronchi and bronchioles. Conversely, NPR-A is rarely found on airway smooth muscle (ASM) and it is not expressed by goblet cells [110]. BNP weakly promotes the bronchorelaxation of ASM in human medium bronchi, although it has been documented that human recombinant BNP administered intravenously elicited a marked relaxant effect in patients with asthma [111,112].
Recent approaches to gout drug discovery: an update
Published in Expert Opinion on Drug Discovery, 2020
Naoyuki Otani, Motoshi Ouchi, Hideo Kudo, Shuichi Tsuruoka, Ichiro Hisatome, Naohiko Anzai
Purine bases are synthesized as nucleotides linked to ribose-5-phosphate (R5P). Purine nucleotides are the substrate for the synthesis of adenosine triphosphate (ATP), which is the energy source of cells, a component of the DNA and RNA, an enzyme cofactor in regulatory and metabolic pathways, and the substrate for regenerating cyclic adenosine monophosphate (cAMP), guanosine triphosphate (GTP), and cyclic guanosine monophosphate (cGMP), which all fulfil critical roles in intracellular signal transduction. Purine metabolism is governed by complex metabolic regulatory mechanisms, including the de novo purine nucleotide synthesis pathway, which generates purine skeletons from phosphoribosyl pyrophosphate (PRPP), and the salvage pathway for purine nucleotide synthesis from free purine bases.
Motor activity and Becker’s muscular dystrophy: lights and shadows
Published in The Physician and Sportsmedicine, 2020
Giuseppe Lanza, Marcello Pino, Francesco Fisicaro, Carla Vagli, Mariagiovanna Cantone, Manuela Pennisi, Rita Bella, Maria Bellomo
A relevant aspect that must be considered when recommending physical exercise for patients with dystrophinopathies is their muscle metabolism. As known, muscle fibers can be distinguished into two main categories [44]: type I fibers (slow), which predominantly use an oxidative metabolism and are predisposed for an aerobic work; and type II fibers (fast), which have a glycolytic metabolism and are predisposed for an anaerobic work. There are also type IIa fibers that have characteristics intermediate between those of the oxidative fibers and the glycolytic fibers. As mentioned, nNOS in BMD is either normal or partially defective both in immunohistochemistry and Western blot studies. The effects of NO are augmented by inhibiting the degradation of the second messenger cyclic guanosine monophosphate through sildenafil or tadalafil, both of which inhibit the enzyme phosphodiesterase 5 (PDE5). In animal models of DMD, PDE5-inhibitors prevent functional ischemia, reduce post-exercise skeletal muscle pathology and fatigue, show amelioration of cardiac damage, and increase cardiac performance. However, the effect on clinical outcomes in DMD and BMD patients have been disappointing, with minor effects on upper limb performance only and no significant effect on ambulation [16].