An Introduction to the Immune System and Vaccines
Patricia G. Melloy in Viruses and Society, 2023
Another critical immunology question is understanding how reinfection by the same pathogen is “remembered” by the adaptive immune system. A strong memory response is necessary to protect the body if a pathogen presents itself in the future. Antibodies are a part of that memory bank. There are five major kinds of antibodies in the body, also known as immunoglobulins (Ig). They include IgM, IgA, IgD, IgG, and IgE (MADGE acronym to remember) (Nicholson 2016). A molecule that is foreign to the body that can react with an antibody is known as an antigen. Immunologists also use the more specific term of “immunogen” as a molecule that reacts with an antibody and causes an immune response (Cruse and Lewis 2009). However, antigen is more commonly used. Any of the four major macromolecules in nature—carbohydrate, nucleic acid, protein, or lipid—could be an antigen (Coico and Sunshine 2015). These macromolecules can be quite large, however, so it is not the entire macromolecule involved in the antigen-antibody interaction. A short region of the antigen, known as an epitope, is considered the “antigenic determinant” (Cruse and Lewis 2009).
Metabolism
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
A continuous supply of energy is required for the survival of the body, and this is provided by oxidation of exogenous organic molecules. The oxidation process requires an adequate supply of oxygen. Metabolic fuels, which exist as macromolecules in the diet (carbohydrates, fats and proteins), are hydrolysed during digestion so that they can be absorbed as simple units and utilized, although fats are resynthesized immediately after absorption. These simple units are then oxidized to provide energy (with nitrogen excreted as urea, carbon as CO2 and hydrogen as water) or converted into various storage forms or synthesized into membranes, enzymes and so on. The metabolic fuels may therefore be derived from either the digestion of a meal or the breakdown of internal stores such as storage organelles or cell constituents.
Francis Crick (1916–2008) and James Watson (1928–)
Krishna Dronamraju in A Century of Geneticists, 2018
Crick was interested in two fundamental problems: how molecules make the transition from the nonliving to the living and how the brain makes a conscious mind. His background made him more qualified for research on the first topic and the field of biophysics. It was at this time of Crick’s transition from physics to biology that he was influenced by both Linus Pauling and Erwin Schrödinger. As Crick saw it, Charles Darwin’s theory of evolution and Gregor Mendel’s genetics and knowledge of the molecular basis of genetics, when combined, revealed the secret of life. It was clear that some macromolecule such as a protein was likely to be the genetic molecule. However, it was well known that proteins are structural and functional macromolecules, some of which carry out enzymatic reactions of cells. In the 1940s, some evidence had been found pointing to another macromolecule, DNA, the other major component of chromosomes, as a candidate genetic molecule. In 1944, Avery et al. showed that a heritable phenotypic difference could be caused in bacteria by providing them with a particular DNA molecule.
Application of plant-derived exosome-like nanoparticles in drug delivery
Published in Pharmaceutical Development and Technology, 2023
Mohadeseh Barzin, Amir Mohammad Bagheri, Mandana Ohadi, Amir Masoud Abhaji, Soodeh Salarpour, Gholamreza Dehghannoudeh
Lipids are hydrophobic macromolecules soluble in nonpolar solvents that act as energy-storing sources and membrane structural components in cells (Casares et al. 2019; Olzmann and Carvalho 2019). Studies revealed that PELNs has a high concentration of phospholipids; however, mammalian-derived exosomes have high levels of cholesterol and sphingomyelin (Zhang et al. 2016; Nemati et al. 2022). In addition, the lipidic content of each spice differs from the others (Zhang et al. 2016). Somehow, the significant lipids of exosomes in garlic and grapefruit belong to the phosphatidylcholines family; on the other hand, the many turmeric lipids and ginger exosomes are classified as phosphatidic acids (Zhang et al. 2016; Teng et al. 2018; Suharta et al. 2021). PELNs performance and cell abortion capacity are both affected by lipidic composition and hydrophobic structural assembling (Karamanidou and Tsouknidas 2021). Further, the differences in lipidic content affect the targets of each particle (Teng et al. 2018; Teng et al. 2021). For example, phosphatidylcholine and phosphatidic acid are essential for the uptake of nanoparticles by Ruminococcaceae members in the guts (Teng et al. 2018). On the other hand, the depletion of phosphatidic acid and phosphatidylcholine in ginger and grapefruit-derived exosomes significantly hinders their uptake by Ruminococcaceae based on research (Teng et al. 2018; Suharta et al. 2021).
Fluorinated vectors for gene delivery
Published in Expert Opinion on Drug Delivery, 2022
Yu Wan, Yuhan Yang, Mingyu Wu, Shun Feng
In general, nucleic acids are macromolecules and negatively charged, thus do not readily cross cell membranes. Additionally, nucleic acids must resist degradation by nucleases, phagocytosis by the reticuloendothelial system, and rapid clearance by the kidneys to reach the site of action intact to exert their effects [5]. Therefore, a safe and efficient gene delivery system is essential to guarantee the effect of gene therapy. Viral and non-viral vectors have been proposed to overcome these limitations. Viral vectors, such as lentivirus, adenovirus, and adeno-associated virus, can achieve efficient gene transfection in various cells [6]. However, they have safety problems such as immunogenicity and genotoxicity, are not easy to prepare cost-effectively on a large scale, and have limited genetic cargo capacity [7]. Viral vectors may be advantageous for diseases that require long-term gene expression, while non-viral vectors provide a more favorable option for diseases that require short-term gene expression [8]. Unlike viral-based vectors, non-viral vectors can overcome these weaknesses to a certain extent, such as good biosafety and are more feasible to prepare on a large scale. Therefore, the development of novel efficient, and safe non-viral gene delivery vectors has become a research hotspot in the field of gene therapy.
Carbohydrates based stimulus responsive nanocarriers for cancer-targeted chemotherapy: a review of current practices
Published in Expert Opinion on Drug Delivery, 2022
Cheng-Wu Zhang, Jun-Gang Zhang, Xue Yang, Wen-Lin Du, Zi-Lin Yu, Zhen-Ye Lv, Xiao-Zhou Mou
Carbohydrates (or saccharides) are one of the four primary groups of macromolecules, along with lipids, proteins, and nucleic acids. Carbohydrates provide unparalleled prospects for nanomedicine applications due to their unique mix of several benefits: (ii) biodegradable/biocompatible (ii) commercially accessible (iv) protein repellent (v) strong water solubility (vii) no agglomeration. Unlike proteins and nucleic acids, the connecting sites between sugar units are not fixed when oligo/polysaccharides are shaped by elongating chains and branch formation. Regioisomers may be produced due to lengthening the sugar sequence at various hydroxy groups, which results in a significant increase in coding capacity. Twenty amino acids yield 6.4 × 107 hexapeptide isomers, but an oligosaccharide with the same number of hexose repeating units yields 1.44 × 1015 isomers [10]. Additionally, the bulk of carbohydrates are present on the outer membranes of cells, in blood and extracellular fluid [11], providing an optimal biological environment for the intravenous administration of nanomedicines.