Chiral Acetal-Based Stereo-Controlled Degradable Polymer Synthesis.

The precise synthesis of chiral polymers remains a significant challenge in polymer chemistry, particularly for applications in advanced biomedical and electronic materials. The development of degradable polymers is important for eco-friendly and advanced materials. Here, we introduce a stereo-controlled degradable polymer via cascade enyne metathesis polymerization and enantioselective acetal synthesis through Pd-catalyzed asymmetric hydroamination. This approach allows for the creation of chiral acetal-based polymers with controlled stereochemistry and degradability, highlighting their potential for use in drug delivery and electronic applications. This concept article reviews the background, development, and potential applications of these stereo-controlled degradable polymers.

Synthesis of Stereocontrolled Degradable Polymer by Living Cascade Enyne Metathesis Polymerization.

A stereocontrolled degradable polymer was synthesized via living cascade enyne metathesis polymerization. Highly stereodefined N,O-acetal-containing enyne monomers were prepared using the Pd-catalyzed hydroamination of alkoxyallenes and ring-closing metathesis. The resulting chiral polymer exhibited a narrow dispersity window. Block copolymers were prepared not only by sequentially adding nondegradable and degradable monomers but also by using enantiomerically different monomers to produce stereocontrolled blocks. Owing to the hydrolyzable N,O-acetal moiety in the backbone structure, the resulting polymer could degrade under acidic conditions generated using various acid concentrations to control the degradation. Additionally, the aza-Diels-Alder reaction modified the polymer without losing the stereochemistry.

Visible Light Photochemical Reactions for Nucleic Acid-Based Technologies.

The expanding scope of chemical reactions applied to nucleic acids has diversified the design of nucleic acid-based technologies that are essential to medicinal chemistry and chemical biology. Among chemical reactions, visible light photochemical reaction is considered a promising tool that can be used for the manipulations of nucleic acids owing to its advantages, such as mild reaction conditions and ease of the reaction process. Of late, inspired by the development of visible light-absorbing molecules and photocatalysts, visible light-driven photochemical reactions have been used to conduct various molecular manipulations, such as the cleavage or ligation of nucleic acids and other molecules as well as the synthesis of functional molecules. In this review, we describe the recent developments (from 2010) in visible light photochemical reactions involving nucleic acids and their applications in the design of nucleic acid-based technologies including DNA photocleaving, DNA photoligation, nucleic acid sensors, the release of functional molecules, and DNA-encoded libraries.

Postoperative residual neuromuscular blockade after reversal based on a qualitative peripheral nerve stimulator response: A randomised controlled trial.

BACKGROUND: Incomplete recovery of neuromuscular blockade is a common postoperative adverse event in the postanaesthesia care unit. OBJECTIVE: We examined and compared the incidence of residual neuromuscular blockade when the recommended dose of neostigmine or sugammadex was administered according to a qualitative nerve stimulator response. DESIGN: A randomised controlled trial. SETTING: A tertiary care hospital in South Korea from September 2017 to November 2017. PATIENTS: Eighty patients aged between 18 and 69 years were included in this study. All were patients scheduled to undergo elective laparoscopic cholecystectomy and who had an American Society of Anaesthesiologists physical status of one or two were eligible. INTERVENTIONS: Patients were allocated randomly to receive neostigmine or sugammadex at the end of surgery. The doses of the reversal agents were based on the response to peripheral nerve stimulation, which was discontinued after administration of the reversal agent. MAIN OUTCOME MEASURES: The primary outcome was the incidence of postoperative residual neuromuscular blockade. The secondary outcomes were the incidences of symptoms or signs of residual neuromuscular blockade such as hypoxaemia, inability to maintain head-lift for 5 s and diplopia. RESULTS: The incidence of residual neuromuscular blockade on arrival in the recovery room was 44.4% in the neostigmine group and 0% in the sugammadex group (P < 0.0001, relative risk = 1.80, 95% confidence interval 1.36 to 2.41). The incidences of adverse events in the recovery room were low and comparable between the groups. CONCLUSION: The incidence of residual neuromuscular blockade on arrival in the recovery room was significantly higher in the neostigmine group than that in the sugammadex group. However, the incidence of adverse events was similar in the neostigmine and sugammadex groups. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03292965.

Arylalkylamine N-acetyltransferase 1 gene (TcAANAT1) is required for cuticle morphology and pigmentation of the adult red flour beetle, Tribolium castaneum.

In the insect cuticle tanning pathway (sclerotization and pigmentation), the enzyme arylalkylamine N-acetyltransferase (AANAT) catalyzes the acetylation of dopamine to form N-acetyldopamine (NADA), which is one of the major precursors for quinone-mediated tanning. In this study we characterized and investigated the function of TcAANAT1 in cuticle pigmentation of the red flour beetle, Tribolium castaneum. We isolated a full length TcAANAT1 cDNA that encodes a protein of 256 amino acid residues with a predicted GCN5-related acetyltransferase domain containing an acetyl-CoA binding motif. TcAANAT1 transcripts were detected at all stages of development with lowest expressions at the embryonic and pharate pupal stages. We expressed and purified the encoded recombinant TcAANAT1 protein (rTcAANAT1) that exhibited highest activity at slightly basic pH values (for example, pH 7.5 to 8.5 using dopamine as the substrate). In addition, rTcAANAT1 acts on a wide range of substrates including tryptamine, octopamine and norepinephrine with similar substrate affinities with Km values in the range of 0.05-0.11 mM except for tyramine (Km = 0.56 mM). Loss of function of TcAANAT1 caused by RNAi had no effect on larval and pupal development. The tanning of pupal setae, gin traps and urogomphi proceeded normally. However, the resulting adults (∼70%) exhibited a roughened exoskeletal surface, separated elytra and improperly folded hindwings. The body wall, elytra and veins of the hindwing of the mature adults were significantly darker than those of control insects probably due to the accumulation of dopamine melanin. A dark pigmentation surrounding the bristles located on the inter-veins of the elytron was evident primarily because of the underlying darkly pigmented trabeculae that partition the dorsal and ventral layers of the elytron. These results support the hypothesis that TcAANAT1 acetylates dopamine and plays a role in development of the morphology and pigmentation of T. castaneum adult cuticle.

Políticas sobre biotecnologías y recursos genéticos

Presenta un estudio acerca de las políticas de biotecnología y recursos genéticos en los alimentos modificados genéticamente y cuales son las relaciones de ese tipo de política con el hambre. Aborda la cuestión de la propiedad intelectual y los cálculos de los costos. Documento en formato PDF, requiere Acrobat Reader.