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The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
Proteins are long chains of amino acids held together by peptide bonds. Each amino acid is composed of an amino group, a carboxyl group and the particular side chain that defines their chemical nature. Individual proteins are constructed from a library of 20 amino acids, which may be subgrouped according to the acidic, basic, uncharged polar or non-polar character of their side chains (Figure 2.2). Like all large molecules, proteins adopt a conformation that confers the most stability. Protein modifications can result from the addition of other substances, such as metal ions (e.g. iron in haemoglobin), lipids (lipoproteins) or carbohydrates (glycoproteins).
Metabolic Laboratory Data
Published in Michael M. Rothkopf, Jennifer C. Johnson, Optimizing Metabolic Status for the Hospitalized Patient, 2023
Michael M. Rothkopf, Jennifer C. Johnson
We make extensive use of the 24-hour UUN and creatinine. The UUN is a great way to determine how catabolic a patient is. As outlined above, the amount of urea excreted per day is a direct reflection of dietary protein breakdown and the conversion of amino acids into glucose. The amino group is liberated in this process and becomes ammonia. Most of the ammonia is converted to urea for excretion and can be easily measured by the UUN. Some of the ammonia along with other nitrogenous metabolites (i.e., uric acid, creatinine, hippuric acid and amino acid derivatives) are excreted in urine, stool and skin. We use a correction factor to account for these, generally 4 g/day.
Finding a Target
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Amino acids are di-functional, containing a basic amine group and acidic carboxyl group. Each of the 20 amino acids is an alpha-amino acid, in other words, the amine substituent is attached to the alpha carbon next to the carbonyl group. Also note that 19 of those amino acids are primary amino acids and only differ in the side chain substituent. Having both acidic and basic groups, amino acids are able to undergo internal acid-base reactions to produce dipolar ions, called zwitterions at a particular pH, known as the isoelectric point, and are amphoteric, acting as both an acid and a base, which is crucial for their involvement in biological catalysis. A polypeptide is synthesised from amino acids by the condensation reaction between the carboxylic acid group of one amino acid with the amino group of the next to form an amide linkage, or peptide bond, via an enzyme-controlled pathway.
Antiglycoxidative properties of amantadine – a systematic review and comprehensive in vitro study
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Miłosz Nesterowicz, Małgorzata Żendzian-Piotrowska, Jerzy Robert Ładny, Anna Zalewska, Mateusz Maciejczyk
Molecular docking analysis did not reveal strong binding sites of amantadine on the BSA structure, which can be a probable reason for the lack of protective effect against protein oxidation/glycation. The source of amantadine’s ability to promote oxidative and carbonyl stress may be another feature of its structure. The amino group attached to the cyclic ring is an activating substituent that may be the reason of prooxidant properties of the compound112. Indeed, the amino group is one of the most biologically active groupings. It significantly boosts the toxicity of many organic substances, which increases proportionally to the number of amino groups113. Thus, the unrecognised effects of amantadine may be related to the promotion of redox imbalance which stimulates endogenous adaptive mechanisms. Oxidant-induced strengthening of the antioxidant barrier is a primary defence mechanism against oxidative and carbonyl stress114–116. This is confirmed by previous studies (Table 2), but further research, both basic and clinical, is needed.
Cryoprotective effect of sericin supplementation in freezing and thawing media on the outcome of cryopreservation in human sperm
Published in The Aging Male, 2020
Faranak Aghaz, Mozafar Khazaei, Asad Vaisi-Raygani, Mitra Bakhtiyari
Sericin is a water-soluble component with a molecular weight of at least 200 kDa. It is consisting of 18 kinds of amino acids most of which have strong polar side groups such as hydroxyl, carboxyl, and amino groups. Sericin is especially rich in aspartic acid (≥19%) as well as serine (≥32%) (Table 1) [19], which has a high content of the hydroxyl group. Experimental evidences confirmed the beneficial effects of sericin such as suppressing lipid peroxidation [20,21], preventing cell death [22] and protecting from various types of oxidative stress [18]. As well as the successful use of sericin has been well documented in the cryopreservation of many mammalian cells like human hepatocytes [23], islet cells [24], adipose tissue derived stem cells [25], bovine embryo [26], and buffalo spermatozoa [27]. The antioxidant capacity of sericin has also been demonstrated in several other cell types including oocyte [28] and embryo [28,29].
The canine gastrointestinal microbiota: early studies and research frontiers
Published in Gut Microbes, 2020
Zongyu Huang, Zhiyuan Pan, Ruifu Yang, Yujing Bi, Xiaohui Xiong
Metabolic disorders in IBD have been widely researched in human patients and mouse colitis models and have surpassed canine models. Fecal SCFAs are decreased by nearly the same amount in both humans and mice with IBD.108–110 Canines with IBD have a lower diversity of several bacteria, which are thought to produce SCFAs.41,111,112 Fecal SCFAs are also decreased in other canine GI diseases such as chronic enteropathy.42 Serum metabolites differ in humans, mice and canines. Decreased serum alanine and valine have been observed in human IBD patients as well as mice, while both of these serum metabolites are increased in canines with IBD.40,59,113,114 Alanine is an important transport metabolite for amino groups in animals; altered concentrations of alanine may indicate an altered amino acid turnover ability in IBD.40 The difference in valine in IBD remains unknown. One possibility is the factor of different nutrient intakes among humans, mice and canines. However, no articles have been published to date regarding abnormal concentrations of serum metabolites in canine IBD. Deep analysis of the bacteria in both the canine and human gut provide opportunities for translating IBD research from canines to humans. A limitation of the studies on canine IBD is that few canines have been evaluated, and further research is essential to explain the similarities and biases of serum metabolites in humans and canines.