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Basic Cell Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
DNA is a long chain of nucleotides and therefore is referred to as a polynucleotide. Each nucleotide is composed of three compounds linked together: (1) phosphoric acid; (2) a sugar, in the form of deoxyribose; and (3) a base (Figure 2.7). Bases are divided into two classes, purine and pyrimidine. In DNA, purines are adenine (A) and guanine (G), and pyrimidines are cytosine (C) and thymine (T). Thymine is very specific for DNA structure; therefore, 3H-thymidine has been used extensively in the study of DNA synthesis. In 1953, Watson and Crick proposed a double-helix structure for DNA in which two bases are joined together by hydrogen bonds.43 A diagrammatic structure of DNA is shown in Figure 2.8. It should be noted that adenine pairs with thymine, whereas cytosine pairs with guanine. Figure 2.9 shows a schematic representation of DNA replication. During replication of each strand, the newly formed strand attaches with the proper base of the old one to form a double-stranded DNA. A new DNA strand was synthesized in vitro by using a specific enzyme polynucleotide pyrophosphorylase, precursor of DNA, and DNA from other sources. The newly formed DNA was identical to DNA that was added to the reaction mixture. This showed conclusively that DNA acts as a template for the synthesis of another strand of DNA.
The Adjuvant Action of Synthetic Polynucleotides on the Immune Response
Published in Edward P. Cohen, A. Arthur Gottlieb, Immune RNA, 2020
Conversely, the adjuvant activity of poly I:C has been shown to be abrogated by a prior injection of bacterial endotoxin.46 Thus, endotoxin given to mice 1 day before 200 μg poly I:C depressed the increase in plaque-forming cells normally caused by the polynucleotide. On the other hand, although poly I:C and endotoxin share several stimulatory and suppressive properties, three injections of 50 μg poly I:C on alternate days followed 48 hr later by endotoxin failed to induce tolerance to the lethal aspects of the latter.47 Yet, normal mice pretreated with poly I:C exhibited complete hyporeactivity to interferon induction by endotoxin, but infection of mice with 0.2 ml of a 14-day culture of BCG (Phipps strain) potentiated the release of interferon by poly I:C and did not enhance sensitization to the lethal aspects of the polynucleotide.48
The Molecular Model and DNA Double Strand Breaks
Published in K. H. Chadwick, Understanding Radiation Biology, 2019
The DNA molecule has a well-defined three-dimensional structure originally determined by Watson and Crick in 1953 (Watson and Crick 1953). Two long polymer chains of alternating sugar and phosphate units are wound around each other in the form of a double helix. The two sugar-phosphate polymer chains are linked at each sugar unit by one of two purine–pyrimidine pairs of nucleotide bases, adenine–thymine pairs (A–T) and guanine–cytosine pairs (G–C), and, because the dimension of the A–T pair is the same as the dimension of the G–C pair, the two sugar-phosphate chains are held parallel to each other, separated by 1.2 nm, so that the structure resembles a long, twisted, lightly coiled, rope ladder on a molecular scale. The two sugar-phosphate strands are wound round each other to make one full turn every 3.4 nm in a right-handed spiral, which in turn is wound around a central axis so that a major groove and a minor groove are formed. Each complete unit of base plus sugar plus phosphate is called a nucleotide so that each strand of the DNA is a polynucleotide chain. The nucleotide purine–pyrimidine pairing occurs every 0.34 nm along the sugar-phosphate chain so that there are ten links holding the chain together for every full turn of the spiral. The sequence of the purine (A, G) and pyrimidine (C, T) bases along the chain forms the basis of the genetic code. The result, illustrated in Figure 1.1, is a very long, thin molecule reaching up to 50 mm in length with a diameter of 2 nm.
Comprehensive engineering of a therapeutic neutralizing antibody targeting SARS-CoV-2 spike protein to neutralize escape variants
Published in mAbs, 2022
Taichi Kuramochi, Siok Wan Gan, Adrian W.S. Ho, Bei Wang, Nagisa Kageji, Takeru Nambu, Sayaka Iida, Momoko Okuda-Miura, Wei Shan Chia, Chiew Ying Yeo, Dan Chen, Wen-Hsin Lee, Eve Zi Xian Ngoh, Siti Nazihah Mohd Salleh, Cheng-I Wang, Tomoyuki Igawa, Hideaki Shimada
The polynucleotides encoding variable regions of the heavy and light chain were synthesized by GenScript Inc. and were cloned into expression vectors containing a polynucleotide encoding the heavy chain constant region or the light chain constant region sequence, respectively. Recombinant antibodies were expressed transiently using the Expi293 Expression System (Thermo Fisher) according to the manufacturer’s instructions. For high throughput antibody generation during the antibody engineering process, antibodies in normal IgG1 format were purified with protein A (GE Healthcare) from supernatant of transient expression. An additional purification step was performed to further evaluate the top two selected candidates by using SEC to remove HMW and low molecular weight components. The heavy chain constant region for the top two selected candidates was replaced with SG1095ACT3. The purified antibodies were kept in a formulation containing 20 mM His, 150 mM Arg, 162.1 mM Asp, 20 mM Met, pH6.0.
Hyaluronic acid in vulvar and vaginal administration: evidence from a literature systematic review
Published in Climacteric, 2021
G. Buzzaccarini, L. Marin, M. Noventa, A. Vitagliano, A. Riva, F. Dessole, G. Capobianco, L. Bordin, A. Andrisani, G. Ambrosini
Few studies used different ways of administration, but they refer to more complicated routes and are not routinely applicable such as platelet-rich plasma or a compressor [25,28]. Interestingly, no study managed to use an injection technique of HA alone. Palmieri injected HA as a consolidation session after polynucleotide primer injection. Intriguingly, the study found better improvement after HA injection than after polynucleotide injection [33]. Moreover, González et al. [34] injected non cross-linked HA plus CaHA and found improvement in histological collagen synthesis and vaginal wall thickening. For this reason, since HA is widely used in esthetic medicine through different injection techniques, it seems reasonable that it could also provide benefits in vagina mucosa [2,3,49]. It is possible that the high vascularized vaginal mucosa resulting in bleeding and possible infections could discourage its use by esthetic gynecologists. However, biomedical engineering has provided extremely thin needles, as fine as 34 Gauge, and cannulae [50,51] that could reduce pain, bleeding and arterial occlusion.
Synthesis, anti-bacterial and anti-protozoal activities of amidinobenzimidazole derivatives and their interactions with DNA and RNA
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Andrea Bistrović, Luka Krstulović, Ivana Stolić, Domagoj Drenjančević, Jasminka Talapko, Martin C. Taylor, John M. Kelly, Miroslav Bajić, Silvana Raić-Malić
ICD spectra of 8b and 9b, in the presence of polyA-polyU, showed an intense increase of signal above r = 0.3, while ICD spectra of 7b with polyC-polyG showed a weaker intercalation signal above r = 0.5. This is in agreement with the results obtained by UV–Vis and thermal melting methods. Minimal changes of the intensity of the CD bands of polyC-polyG upon titration with compounds 7a, 8a–8e, and 9d, suggest a non-specific binding mode. Most probably compounds bind on the outside of the polyC-polyG polynucleotide. The intensity of negative ICD bands in polyA-polyU ICD spectra was also observed to be more intense than those in polyC-polyG spectra obtained with the same compound.