Efficient Reverse Transcription Using Locked Nucleic Acid Nucleotides towards the Evolution of Nuclease Resistant RNA Aptamers

Background: Modified nucleotides are increasingly being utilized in the de novo selection of aptamers for enhancing their drug-like character and abolishing the need for time consuming trial-and-error based post-selection modifications. Locked nucleic acid (LNA) is one of the most prominent and successful nucleic acid analogues because of its remarkable properties, and widely explored as building blocks in therapeutic oligonucleotides. Evolution of LNA-modified RNA aptamers requires an efficient reverse transcription method for PCR enrichment of the selected RNA aptamer candidates. Establishing this key step is a pre-requisite for performing LNA-modified RNA aptamer selection

Enzymatic Recognition of 2′-Modified Ribonucleoside 5′-Triphosphates: Towards the Evolution of Versatile Aptamers

The quest for effective, selective and nontoxic nucleic-acid-based drugs has led to designing modifications of naturally occurring nucleosides. A number of modified nucleic acids have been made in the past decades in the hope that they would prove useful in target-validation studies and therapeutic applications involving antisense, RNAi, aptamer, and ribozyme-based technologies. Since their invention in the early 1990s, aptamers have emerged as a very promising class of therapeutics, with one drug entering the market for the treatment of age-related macular degeneration. To combat the limitations of aptamers containing naturally occurring nucleotides, chemically modified nucleotides have to be used. In order to apply modified nucleotides in aptamer drug development, their enzyme-recognition capabilities must be understood. For this purpose, several modified nucleoside 5′-triphosphates were synthesized and investigated as substrates for various enzymes. Herein, we review studies on the enzyme-recognition of various 2′-sugar-modified NTPs that were carried out with a view to their effective utilization in SELEX processes to generate versatile aptamers

A new tool to assess Clinical Diversity In Meta-analyses (CDIM) of interventions

Objective: To develop and validate Clinical Diversity In Meta-analyses (CDIM), a new tool for assessing clinical diversity between trials in meta-analyses of interventions. Study design and setting: The development of CDIM was based on consensus work informed by empirical literature and expertise. We drafted the CDIM tool, refined it, and validated CDIM for interrater scale reliability and agreement in three groups. Results: CDIM measures clinical diversity on a scale that includes four domains with 11 items overall: setting (time of conduct/country development status/units type); population (age, sex, patient inclusion criteria/baseline disease severity, comorbidities); interventions (intervention intensity/strength/duration of intervention, timing, control intervention, cointerventions); and outcome (definition of outcome, timing of outcome assessment). The CDIM is completed in two steps: first two authors independently assess clinical diversity in the four domains. Second, after agreeing upon scores of individual items a consensus score is achieved. Interrater scale reliability and agreement ranged from moderate to almost perfect depending on the type of raters. Conclusion: CDIM is the first tool developed for assessing clinical diversity in meta-analyses of interventions. We found CDIM to be a reliable tool for assessing clinical diversity among trials in meta-analysis. (c) 2021 Elsevier Inc. All rights reserved