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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).
Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Some main polypeptides and peptides in the human body include glutathione, glucagon, insulin, calcitonin, amylin, parathyroid hormone, angiotensin, oxytocin, and brain natriuretic peptide, also known as B-type natriuretic peptide (BNP) (36, 38, 41–46). Peptides can be used in the treatment of various diseases, including endocrine dysfunctions (diabetes, thyroid disorders, osteoporosis, etc.), infectious diseases, cancer, central nervous system disorders, and gastroenterologic diseases, generally by injection (42). Already more than 100 peptide-based drugs have reached the market, and hundreds of peptidergic compounds are in clinical or preclinical studies (42).
In Vivo Models of Smooth Muscle Growth
Published in Alastair G. Stewart, AIRWAY WALL REMODELLING in ASTHMA, 2020
In addition to consideration of the possible effects of leukotriene released in association with hyperpnea- or exercise-induced airway narrowing, sensory neuropeptides themselves merit attention. Peptides released from sensory neurons could directly or indirectly induce smooth muscle growth. Direct proliferative effects have been demonstrated in vitro with related cell types, such as lung fibroblasts50 and vascular smooth muscle cells.51 Indirect effects could occur following tachykinin-induced increases in vascular permeability, with release of other mitogens such as thrombin, or following tachykinin-induced release of other mediators such as IL-8 or leukotrienes, as already mentioned. In the guinea pig model, the role of tachykinins in the induction of smooth muscle proliferation has been addressed by pretreating the animals with capsaicin, and it appears that they are not essential to the process. Prior neuropeptide depletion did not prevent the development of smooth muscle replication.40
Emergence of mRNA vaccines in the management of cancer
Published in Expert Review of Vaccines, 2023
Mohamad Irfan Mohamad Razif, Nabilah Nizar, Nur Hannah Zainal Abidin, Syasya Nasuha Muhammad Ali, Wan Nurul Najihah Wan Zarimi, Junaidi Khotib, Deny Susanti, Muhammad Taufiq Mohd Jailani, Muhammad Taher
Generally, peptide-based delivery systems offer higher transfection efficiency and reduce harmful effects compared to lipid-based delivery systems [27]. Peptides may have several advantages including biocompatibility, simplicity in synthesis, small size, avoidance of off-target side effects, and attaining the desired effects at lower dosages [28]. CPPs are a non-viral vector type composed of either cationic or amphipathic amino acids which are able to penetrate the cell membrane [26,28]. Large liposomes and bulky molecules can be more easily and effectively internalized into the cell when arginine-rich cationic CPPs are present. These CPP aid in lipid membrane penetration [29] due to their guanidinium group which is responsible for creating hydrogen bonds and electrostatic forces with the cell membrane [26]. Amphipathic CPPs contain both hydrophilic and lipophilic amino acid residues which can interact with neutral and cationic residues of lipid bilayer membrane [30]. Due to their powerful hydrophobic contact and penetration into lipid bilayers of the cell membrane, amphipathic CPPs have a high transfection effectiveness [26]. They also stated that cationic molecules have higher penetration efficiency than anionic molecules as the majority of cancer cell surfaces are generally composed of anionic residues.
Resveratrol Blunts Mitochondrial Loss in Slow and Mixed Skeletal Muscle Phenotypes of Non-Human Primates following a Long-Term High Fat/Sugar Diet
Published in Journal of Dietary Supplements, 2023
Jon-Philippe K. Hyatt, Rafael de Cabo, Julie A. Mattison
Stephenson et al. (61) reported that, unlike in the soleus muscle, the fast extensor digitorum longus muscle exhibited a slight (13–18%), but significant, increase in OXPHOS proteins following a 12-week high fat/sucrose (e.g. Western) diet. Here, no significant increases were observed in HFS muscles, although RESV treatment elicited a modest increase in proteins of complexes I, II, and III in HFSR soleus, but not plantaris, muscles. It is possible that without the additive stimulus of, for example, aerobic exercise, RESV supplementation has minimal impact on OXPHOS protein expression (49) and respiration (62, 63) particularly in a mixed muscle phenotype. Given the emerging role of humanin and MOTS-c in modulating glucose and/or lipid metabolism (36, 43–45), we expected expression to increase within HFS and HFSR muscles, but detected no changes in HFS or HFSR groups. It is possible that the expression of these peptides are responsive to more acute perturbations in diet and/or muscle activity than lengthy interventions used in the present study (45). Likewise, proteins associated with fusion/fission events of the mitochondria were not impacted in the presence of RESV treatment, although we cannot discount the occurrence of molecular habituation to chronic exposure to diet and RESV on gene expression or protein translation, which may differ from acute or short-term consumption (64).
Patent landscape highlighting therapeutic implications of peptides targeting myristoylated alanine-rich protein kinase-C substrate (MARCKS)
Published in Expert Opinion on Therapeutic Patents, 2023
Vikas Yadav, Amarish Kumar Sharma, Gaurav Parashar, Nidarshana Chaturvedi Parashar, Seema Ramniwas, Manoj Kumar Jena, Hardeep Singh Tuli, Kiran Yadav
Peptides are short chains of amino acids that are naturally occurring in the body and are known to be involved in various physiological processes. The major advantage of using peptides as drugs is their specificity, as peptides can target specific receptors or enzymes in the body and have a lower potential for off-target effects compared to small-molecule drugs [15,16]. Peptides also offer a lower toxicity profile due to their rapid metabolism and clearance from the body, which helps reduce the risk of long-term adverse effects [17]. However, this characteristic property is sometimes considered as a limitation for peptide-based drug discovery. Several advancements have been postulated to overcome the rapid clearance or proteolytic degradation of peptide-based drugs, but these are beyond the scope of the present review.