[Role and Mechanism of Low Molecular-Weight-Organic Acids in Enhanced Phytoremediation of Heavy Metal Contaminated Soil].

Phytoremediation is an environmentally friendly technology to remove heavy metals from polluted soil by using the physical and chemical roles of plants. This can effectively reduce the production of secondary pollutants and is economically feasible. Low molecular-weight-organic acids (LMWOAs) are biodegradable and environmentally friendly and have strong application potential in the phytoremediation of heavy metal-contaminated soils. The role and mechanism of LMWOAs in phytoremediation was elaborated on in this study with the aim to:① regulate the development of roots, stems, and leaves; increase plant biomass; and enhance plant enrichment of heavy metals; ② improve photosynthesis, enhance plant resistance, and promote tolerance to heavy metals; ③ change the properties of rhizosphere soil, improve rhizosphere microbial activity, and promote the absorption of heavy metals; and ④ change the form of heavy metals, reduce the toxicity of heavy metals, and improve transport efficiency. Moreover, the advantages, disadvantages, and application of LMWOAs in enhanced phytoremediation of heavy metal-contaminated soil were explored in this study. Finally, the research direction of LMWOAs in the phytoremediation of heavy metal-contaminated soils was proposed, which will have practical scientific significance for the research and application of LMWOAs in future phytoremediation.

Diagnostic value of chest computed tomography imaging for COVID-19 based on reverse transcription-polymerase chain reaction: a meta-analysis.

BACKGROUND: The computed tomography (CT) diagnostic value of COVID-19 is controversial. We summarized the value of chest CT in the diagnosis of COVID-19 through a meta-analysis based on the reference standard. METHODS: All Chinese and English studies related to the diagnostic value of CT for COVID-19 across multiple publication platforms, was searched for and collected. Studies quality evaluation and plotting the risk of bias were estimated. A heterogeneity test and meta-analysis, including plotting sensitivity (Sen), specificity (Spe) forest plots, pooled positive likelihood ratio (+LR), negative likelihood ratio (-LR), dignostic odds ratio (DOR) values and 95% confidence interval (CI), were estimated. If there was a threshold effect, summary receiver operating characteristic curves (SROC) was further plotted. Pooled area under the receiver operating characteristic curve (AUROC) and 95% CI were also calculated. RESULTS: Twenty diagnostic studies that represented a total of 9004 patients were included from 20 pieces of literatures after assessing all the aggregated studies. The reason for heterogeneity was caused by the threshold effect, so the AUROC = 0.91 (95% CI: 0.89-0.94) for chest CT of COVID-19. Pooled sensitivity, specificity, +LR, -LR from 20 studies were 0.91 (95% CI: 0.88-0.94), 0.71 (95% CI: 0.59-0.80), 3.1(95% CI: 2.2-4.4), 0.12 (95% CI: 0.09-0.17), separately. The I2 was 85.6% (P = 0.001) by Q-test. CONCLUSIONS: The results of this study showed that CT diagnosis of COVID-19 was close to the reference standard. The diagnostic value of chest CT may be further enhanced if there is a unified COVID-19 diagnostic standard. However, please pay attention to rational use of CT.

Exploring calcium ion-dependent effect on the intermolecular interaction between human secreted phospholipase A2 and its peptide inhibitors in coronary artery disease.

Human secreted phospholipase A2 (hsPLA2) is a small calcium ion (Ca2+)-regulatory protein secreting from platelets, eosinophils and T-lymphocytes, which has been established as an important biomarker and potential target for the diagnosis and therapy of coronary artery disease. Short peptide inhibitors are used to competitively suppress the enzymatic activity of hsPLA2. Here, Ca2+ effect on the intermolecular recognition and interaction between hsPLA2 and its peptide inhibitors is investigated systematically by using molecular modeling and bioinformatics analysis. Dynamics simulations reveal that the hsPLA2 structure bound with Ca2+ is rather stable and has low thermal motion; removal of Ca2+ considerably increases structural flexibility and intrinsic disorder of the protein. Energetics calculations suggest that presence of Ca2+ can effectively promote the interaction of hsPLA2 with peptide inhibitors. In particular, the local substructures of hsPLA2 such as helix H1, loop L2 and double-stranded ß-sheet DS that participate in peptide recognition are involved in or nearby Ca2+-coordinating site and can be directly stabilized by the Ca2+. In addition, a significant concentration-dependent effect of Ca2+ on peptide-hsPLA2 binding is observed in vitro, that is, a little of Ca2+ can largely improve peptide binding affinity, but high Ca2+ concentration does not increase the affinity substantially. The correlation between calculated free energy and experimental binding affinity over different peptide inhibitors is improved considerably by adding Ca2+ to hsPLA2. Specifically, the FLSYK peptide can generally bind to Ca2+-bound hsPLA2 with a moderate or high affinity (Kd ranges between 56 and 210 µM), but have only a modest affinity or even nonbinding to Ca2+-free hsPLA2 (Kd > 400 µM or = n.d.).