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Membrane Transport
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
Many substances are not distributed between cells and their surroundings according to their electrochemical potential. For instance, many cells extrude sodium ions and concentrate potassium ions. This could in principle occur by coupled transport; that is, a gradient of one type of ion (for instance, protons) could drive the movement of another ion species (for instance, sodium) against its gradient. When there is direct coupling between movement of a substance and a metabolic reaction (mostly the breakdown of ATP) the process is called active transport.4
Disease Prediction and Drug Development
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
A metabolic reaction depends upon many factors: 1) concentration of the substrate; 2) concentration of the enzyme; 3) presence of other related enzymes that work on the same substrate; 4) concentration of the end-product and 5) environmental factor such as PH-value, salinity and so on. The assumption is that the reaction occurs in a steady state. In a steady state, the concentration of each substrate remains invariant. Each substrate is modeled as a variable, and the rate of change of the concentration is modeled using partial differential equations.
Perioperative Metabolic Therapies in Orthopedics
Published in Kohlstadt Ingrid, Cintron Kenneth, Metabolic Therapies in Orthopedics, Second Edition, 2018
With the usual preoperative lab studies, several additional laboratory studies can be very useful in assessing potential nutritional deficiencies or surgical risks (see Table 17.1). Supplementing a low normal nutrient value prepares the patient for the catabolic stress of healing. Scientific literature has described “metabolic therapy” as that which involves the administration of a substance normally found in the body to enhance a metabolic reaction. This can be achieved in two ways: one, by giving a substance to achieve greater than normal levels in the body to drive a biochemical reaction in the desired direction; two, by using a substance to correct the relative or absolute deficiency of a cellular component. This concept is useful in the context of prescribing nutrients to improve surgical outcomes.
Dynamics and metabolic profile of oral keratinocytes (NOK-si) and Candida albicans after interaction in co-culture
Published in Biofouling, 2021
Paula Masetti, Paula Volpato Sanitá, Janaina Habib Jorge
Amino acids are essential for cell metabolism. They act in the production of proteins, are an alternative source of energy, and participate in the synthesis of other metabolites, such as glucose (Kidd and Kerr 1996; Sellick et al. 2015; Sousa et al. 2016; Yang and Vousden 2016). During the analysis of the metabolites, several amino acids were identified, among them alanine, glycine, serine, and threonine. In general, the abundance of the four amino acids identified was higher in the co-culture, in comparison with their abundance in the cells growing alone (Figure 3). One possible explanation is that, with cellular interaction, there may have been a greater production of these amino acids as a defense mechanism, so the production of cellular proteins was enhanced. In addition, data from the metabolism of serine and threonine can be related to the metabolic interactions in the activity of the citric acid cycle. Both amino acids are products of the metabolic reaction from the breakdown of the pyruvate molecule. Additionally, serine and threonine can follow several metabolic fates (dependent on the relative activities of cytosolic and mitochondrial enzymes), including pyruvate (with a potential consequence for alanine production).
Mechanistic studies on the drug metabolism and toxicity originating from cytochromes P450
Published in Drug Metabolism Reviews, 2020
Chaitanya K. Jaladanki, Anuj Gahlawat, Gajanan Rathod, Hardeep Sandhu, Kousar Jahan, Prasad V. Bharatam
QC methods are being widely used to address key questions about CYP450-catalyzed reactions. The information being sought from such analysis includes: (i) the electronic structure of reactants, intermediates, products and transition states; (ii) the absolute and the relative energies of all the species; (iii) the details of molecular orbitals (shapes and energies); (iii) estimation of partial atomic charges, electrophilicity and nucleophilicity parameters; (iv) surface properties (molecular electrostatic potential); (v) reaction pathways, by establishing the energy profiles of the metabolic reactions; (vi) internal surface distribution of electron density, spin density (Gao and Truhlar 2002; Friesner and Guallar 2005; Shaik et al. 2010; Siegbahn and Blomberg 2010; Rydberg et al. 2012; Blomberg et al. 2014; Hirao et al. 2014). The transition states on the enzyme-catalyzed metabolic reaction pathways are central and cannot be studied experimentally owing to their short-lived character (Becke 1993), but the same can be obtained using QC methods with sufficient clarity. Moreover, the interactions stabilizing these transition states cannot be determined by experimental methods. Thus, QC methods are utilized for the overall understanding of the complexities and challenges in drug metabolism studies.
Mass balance study of [14C]SHR0302, a selective and potent JAK1 inhibitor in humans
Published in Xenobiotica, 2023
Xinyu Ge, Sheng Ma, Shu Yan, Yali Wu, Chong Chen, Chongzhuang Tang, Yan Zhan, Yi-cong Bian, Kai Shen, Sheng Feng, Xuehu Gao, Dafang Zhong, Hua Zhang, Li-yan Miao, Xing-xing Diao
Investigation of the absorption, metabolism, and excretion of SHR0302 helps to understand the metabolic and elimination pathways utilised by SHR0302. In this study, 100.56% ± 1.51% of the dose was recovered in urine (60.95% ± 11.62%) and faecal (39.61% ± 10.52%) samples 168 h after oral administration of 8 mg (80 µCi) [14C]SHR0302, suggesting that renal excretion is the main excretion pathway for SHR0302. Unchanged SHR0302 was the main drug-related component in plasma and faecal samples. In urine samples, SHR161279 was the main drug-related component. The metabolic reaction of SHR0302 in the human body is mainly through mono-oxidation and glucuronidation. The main metabolic location of SHR0302 in the human body is the pyrrolopyrimidine ring.