High Chemoselectivity of an Advanced Iron Catalyst for the Hydrogenation of Aldehydes with Isolated CC Bond: A Computational Study

Knölker’s iron complex is a “green” catalyst that exhibits low toxicity and is abundant in nature. Density functional theory (DFT) was used to explore the highly chemoselective nature of the catalytic hydrogenation of CH₂CHCH₂CHO. An outer-sphere concerted hydrogen transfer was found to be the most reasonable kinetic route for the hydrogenation of the olefin. However, the CC hydrogenation reaction has a high free energy barrier of 28.1 kcal/mol, requiring a high temperature to overcome. By comparison, the CHO bond concerted hydrogen-transfer reaction catalyzed using Knölker’s iron catalyst has an energy barrier of only 14.0 kcal/mol. Therefore, only the CHO of CH₂CHCH₂CHO can be hydrogenated in the presence of Knölker’s catalyst at room temperature, due to kinetic domination. All computational results were in good agreement with experimental results

Reproducibility of Digital PCR Assays for Circulating Tumor DNA Analysis in Advanced Breast Cancer

<div><p>Circulating tumor DNA (ctDNA) analysis has the potential to allow non-invasive analysis of tumor mutations in advanced cancer. In this study we assessed the reproducibility of digital PCR (dPCR) assays of circulating tumor DNA in a cohort of patients with advanced breast cancer and assessed delayed plasma processing using cell free DNA preservative tubes. We recruited a cohort of 96 paired samples from 71 women with advanced breast cancer who had paired blood samples processed either immediately or delayed in preservative tubes with processing 48–72 hours after collection. Plasma DNA was analysed with multiplex digital PCR (mdPCR) assays for hotspot mutations in <i>PIK3CA</i>, <i>ESR1</i> and <i>ERBB2</i>, and for <i>AKT1</i> E17K. There was 94.8% (91/96) agreement in mutation calling between immediate and delayed processed tubes, kappa 0.88 95% CI 0.77–0.98). Discordance in mutation calling resulted from low allele frequency and likely stochastic effects. In concordant samples there was high correlation in mutant copies per ml plasma (r² = 0.98; p<0.0001). There was elevation of total cell free plasma DNA concentrations in 10.3% of delayed processed tubes, although overall quantification of total cell free plasma DNA had similar prognostic effects in immediate (HR 3.6) and delayed (HR 3.0) tubes. There was moderate agreement in changes in allele fraction between sequential samples in quantitative mutation tracking (r = 0.84, p = 0.0002). Delayed processing of samples using preservative tubes allows for centralized ctDNA digital PCR mutation screening in advanced breast cancer. The potential of preservative tubes in quantitative mutation tracking requires further research.</p></div

Agreement in change in mutation abundance in sequential samples between immediate EDTA and delayed Streck samples.

<p>A. Agreement in fold change in mutation allele frequency between immediate and delayed samples in sequential samples from 6 patients (r = 0.85, p = 0.0002). B. Agreement in fold change in mutant copies per ml between immediate and delayed samples in sequential samples from 6 patients (r = 0.84, p = 0.0003).</p

Mutation frequency observed in advanced breast cancer.

<p>A. Mutation frequency observed in plasma of patients with advanced cancer. Only samples with concordant mutations in both samples are assessed as having a mutation. Individual mutations observed for B. <i>PIK3CA</i> and C. <i>ESR1</i> mutations detected.</p

Comparison of total free plasma DNA levels between immediate processed EDTA samples and delayed processed Streck samples.

<p>A. Correlation plasma DNA levels of immediate processed EDTA samples and delayed processed Streck samples. Pearson correlation coefficient. B. Bland-Altman plot of data in part A with dashed lines representing 95% CI. C. Overall survival with plasma DNA quantified in immediate EDTA tubes divided on high plasma DNA levels above the upper quartile versus low plasma DNA below the upper quartile. Log rank test with hazard ratio (HR) and 95% confidence intervals (95% CI). D. Overall survival with plasma DNA quantified in delayed Streck tubes divided on high plasma DNA levels above the upper quartile versus low plasma DNA below the upper quartile. Log rank test with hazard ratio.</p

Agreement in mutation calling between immediate EDTA and delayed Streck tubes.

<p>A. Contingency table for mutation detection on immediately processed tubes versus delayed processing tubes,. B. Scatter plot of mutation allele frequency in concordant vs discordant samples. Mann Whitney U test. C. Correlation of mutational allele frequent frequency on immediate and delayed processing tubes. Pearson correlation coefficient. D. Correlation of mutant copies per ml of plasma in immediate and delayed processing tubes. Pearson correlation coefficient.</p

Clinical and pathological characteristics of study patients.

<p>Clinical and pathological characteristics of study patients.</p

Additional file 1 of Remote evaluation of sleep to enhance understanding of early dementia due to Alzheimer’s Disease (RESTED-AD): an observational cohort study protocol

Additional file 1: SM 1. Further Statistical Analysis of Data Pertaining to Secondary Hypotheses. SM 2. RESTED Sleep Questionnaire

Additional file 1 of Sertraline for anxiety in adults with a diagnosis of autism (STRATA): study protocol for a pragmatic, multicentre, double-blind, placebo-controlled randomised controlled trial

Additional file 1. A multicentre double-blind placebo-controlled randomised trial of SerTRaline for AnxieTy in adults with a diagnosis of Autism (STRATA)