Spokewise Total Syntheses of Four Erythrina Alkaloids and Telescoped Syntheses of Six Additional Alkaloids.

Based on rich sulfur-involving chemical transformations, a novel spokewise synthetic strategy, a subclass of the collective strategies, has been developed to concisely synthesize four erythrina alkaloids through a single-step transformation from a common synthetic precursor. Moreover, six additional erythrina alkaloids have also been synthesized by subsequent 1-2 steps chemical transformations. The current synthetic approaches provide a valuable platform for collective total syntheses of erythrina alkaloids and pseudo-natural erythrina alkaloids.

Machine learning algorithms assist early evaluation of enteral nutrition in ICU patients.

Background: This study applied machine learning (ML) algorithms to construct a model for predicting EN initiation for patients in the intensive care unit (ICU) and identifying populations in need of EN at an early stage. Methods: This study collected patient information from the Medical Information Mart for Intensive Care IV database. All patients enrolled were split randomly into a training set and a validation set. Six ML models were established to evaluate the initiation of EN, and the best model was determined according to the area under curve (AUC) and accuracy. The best model was interpreted using the Local Interpretable Model-Agnostic Explanations (LIME) algorithm and SHapley Additive exPlanation (SHAP) values. Results: A total of 53,150 patients participated in the study. They were divided into a training set (42,520, 80%) and a validation set (10,630, 20%). In the validation set, XGBoost had the optimal prediction performance with an AUC of 0.895. The SHAP values revealed that sepsis, sequential organ failure assessment score, and acute kidney injury were the three most important factors affecting EN initiation. The individualized forecasts were displayed using the LIME algorithm. Conclusion: The XGBoost model was established and validated for early prediction of EN initiation in ICU patients.

Enantioselective total syntheses of six natural and two proposed meroterpenoids from Psoralea corylifolia.

The first enantioselective total syntheses of six natural and two proposed meroterpenoids isolated from Psoralea corylifolia have been achieved in 7-9 steps from 2-methylcyclohexanone. The current synthetic approaches feature a high level of synthetic flexibility, stereodivergent fashion and short synthetic route, thereby providing a potential platform for the preparation of numerous this-type meroterpenoids and their pseudo-natural products.

The organocatalytic enantiodivergent fluorination of ß-ketodiaryl-phosphine oxides for the construction of carbon-fluorine quaternary stereocenters.

Commercially available cinchona alkaloids that can catalyze the enantiodivergent fluorination of ß-ketodiarylphosphine oxides were developed to construct carbon-fluorine quaternary stereocenters. This protocol features a wide scope of substrates and excellent enantioselectivities, and it is scalable.

Finding regulatory sequences.

DNA regulatory sequences control gene expression by forming DNA-protein complex with specific DNA binding protein. A major task of studies of gene regulation is to identify DNA regulatory sequences in genome-wide. Especially with the rapid pace of genome project, the function of DNA regulatory sequences becomes one of the focuses in functional genome era. Several approaches for screening and characterizing DNA regulatory sequences emerged one by one, from initial low-throughput methods to high-throughput strategies. Even though at present bioinformatics tools facilitate the process of screening regulatory fragments, the most reliable results will come from experimental test. This article highlights some experimental methods for the identification of regulatory sequences. A brief review of the history and procedures for selection methods are provided. Tendency as well as limitation and extension of these methods are also presented.

Characterization of the aminated agarose nanoparticles labeled with fluorescein isothiocyanate.

Incorporating an organic fluorescence agent into nanoparticles can significantly promote its fluorescent efficiency. In this article, a novel fluorescein isothiocyanate labeling aminated agarose (FITC-AA) was synthesized and tested as an effective fluorescent labeling agent. FITC-AA could spontaneously form nanoparticles with a diameter less than 200 nm below 37°C due to gelling effect of the agarose. Cell culture experiments confirmed that 3T3 fibroblast cells could be marked by fluorescent FITC-AA nanoparticles and the labeling time sustained longer than by FITC alone. This finding demonstrates that the fluorescent labeling of cells can be enhanced when fluorescent nanoparticles are used as markers.