Background: CD44 is widely used as a putative cancer stem cells (CSCs) marker for colorectal cancer (CRC). However, the prognostic role of CD44 in CRC remains controversial. Methods: We performed a systematic review and meta-analysis to evaluate the association of various CD44 isoforms and overall survival (OS) and clinicopathological features of CRC patients. Results: A total of 48 studies were included in the meta-analysis. Total CD44 isoforms overexpression was significantly correlated with worse OS of patients with CRC (HR = 1.32, 95% CI = 1.08–1.61, P = 0.007). In a stratified analysis, a higher level of either CD44v6 or CD44v2 had an unfavorable impact on OS (HR CD44v6 = 1.50, 95% CI = 1.10–2.14, P = 0.010; HR CD44v2 = 2.93, 95% CI = 1.49–5.77, P = 0.002). Additionally, CD44 was shown to be associated with some clinicopathological features, such as lymph node metastasis (OR CD44 = 1.56, 95% CI = 1.01–2.41, P = 0.044; OR CD44v6 = 1.97, 95% CI = 1.19–3.26, P = 0.008; OR Total CD44 isoforms = 1.57, 95% CI = 1.15–2.14, P = 0.004), distant metastasis (OR CD44 = 2.90, 95% CI = 1.08–7.83, P = 0.035; OR Total CD44 isoforms = 1.89, 95% CI = 1.02–3.53, P = 0.044). Moreover, a high level of CD44 showed a possible correlation with poor differentiation (OR Total CD44 isoforms = 1.44, 95% CI = 1.00–2.08, P = 0.051), elevated level of CD44v6 tend to be correlated with tumor size (OR = 1.71, 95% CI = 0.99–2.96, P = 0.056). Conclusions: This meta-analysis demonstrated that CD44 overexpression might be an unfavorable prognostic factor for CRC patients and could be used to predict poor differentiation, lymph node metastasis and distant metastasis.

Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics technology greatly push forward the study of lipidomics. Among them, mass spectrometry (MS) is the most important technology for lipid analysis. In this review, the methodology based on MS for lipid analysis was introduced. It is believed that along with the rapid development of MS and its further applications to lipid analysis, more functional lipids will be identified as biomarkers and therapeutic targets and for the study of the mechanisms of disease.

O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal-and solvent-free conditions. The IL 1butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO 3 H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO 3 H-BMIm][OTf] could form three strong Hbonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., > 99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.

A unique ring-closure method was developed for the preparation of cyclic polymers based on the combination of atom transfer radical polymerization and UV-induced strain promoted azide–alkyne cycloaddition reaction.

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Transformation of carbon dioxide (CO2) into valuable chemicals is of great importance, and development of novel and efficient catalysts is crucial. Herein, we found that the renewable lecithin could be used as an efficient organocatalyst for the formylation and methylation of various amines with CO2 to corresponding formamides and methylamines via the construction of new C–N bonds using PhSiH3 as the hydrogen source, and satisfactory yields could be obtained. More importantly, the selectivity of the products could be easily controlled by the molar ratio of reactants (i.e., CO2, amines, and PhSiH3) and reaction temperature. In the catalytic cycle, formamides and methylamines were generated by converting the carbon (+4) in CO2 into +2 and −2 via 2-electron and 6-electron reduction pathway, respectively.

Dehydrative cyclization of diols to O-heterocycles is attractive, but acid and/or metal-based catalysts are generally required. Here, we present a hydrogen-bond donor and acceptor cooperative catalysis strategy for the synthesis of O-heterocycles from diols in ionic liquids [ILs; e.g., 1-hydroxyethyl-3-methyl imidazolium trifluoromethanesulfonate ([HO-EtMIm][OTf])] under metal-free, acid-free, and mild conditions. [HO-EtMIm][OTf] is tolerant to a wide diol scope, shows performance even better than H2SO4, and affords a series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines, dioxanes, and thioxane in high yields. Mechanism investigation indicates that the IL cation and anion serve as hydrogen-bond donor and acceptor, respectively, to activate the C─O and O─H bonds of alcohol via hydrogen bonds, which synergistically catalyze dehydrative cyclization of diols to O-heterocycles. Notably, the products could be spontaneously separated after reaction because of their immiscibility with the IL, and the IL could be recycled. This green strategy has great potential for application in industry.

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