Abstract
The delivery of alkyl radicals through photocatalytic deoxygenation of primary alcohols under mild conditions is a so far unmet challenge. In this report, we present a one-pot strategy for ...deoxygenative Giese reaction of alcohols with electron-deficient alkenes, by using xanthate salts as alcohol-activating groups for radical generation under visible-light photoredox conditions in the presence of triphenylphosphine. The convenient generation of xanthate salts and high reactivity of sequential C–S/C–O bond homolytic cleavage enable efficient deoxygenation of primary, secondary and tertiary alcohols with diverse functionality and structure to generate the corresponding alkyl radicals, including methyl radical. Moreover, chemoselective radical monodeoxygenation of diols is achieved via selective formation of xanthate salts.
Melatonin (N‐acetyl‐5‐methoxytryptamine), an indoleamine produced in many organs including the pineal gland, was initially characterized as a hormone primarily involved in circadian regulation of ...physiological and neuroendocrine function. Subsequent studies found that melatonin and its metabolic derivatives possess strong free radical scavenging properties. These metabolites are potent antioxidants against both ROS (reactive oxygen species) and RNS (reactive nitrogen species). The mechanisms by which melatonin and its metabolites protect against free radicals and oxidative stress include direct scavenging of radicals and radical products, induction of the expression of antioxidant enzymes, reduction of the activation of pro‐oxidant enzymes, and maintenance of mitochondrial homeostasis. In both in vitro and in vivo studies, melatonin has been shown to reduce oxidative damage to lipids, proteins and DNA under a very wide set of conditions where toxic derivatives of oxygen are known to be produced. Although the vast majority of studies proved the antioxidant capacity of melatonin and its derivatives, a few studies using cultured cells found that melatonin promoted the generation of ROS at pharmacological concentrations (μm to mm range) in several tumor and nontumor cells; thus, melatonin functioned as a conditional pro‐oxidant. Mechanistically, melatonin may stimulate ROS production through its interaction with calmodulin. Also, melatonin may interact with mitochondrial complex III or mitochondrial transition pore to promote ROS production. Whether melatonin functions as a pro‐oxidant under in vivo conditions is not well documented; thus, whether the reported in vitro pro‐oxidant actions come into play in live organisms remains to be established.
The root is the first plant organ to get in contact with the toxin cadmium (Cd), which is a widespread soil contaminant. Cd inhibits the growth of the primary root, but the mechanisms underlying this ...inhibition remain elusive. In this study, we used physiological, pharmacological and genetic approaches to investigate the roles of nitric oxide (NO) and auxin in Cd‐mediated inhibition of Arabidopsis thaliana root meristem growth. Our study demonstrated that in the first 12 h of exposure, Cd inhibits primary root elongation through a decrease in the sizes of both the elongation and meristematic zones. Following Cd exposure, a decrease in auxin levels is associated with reduced PIN1/3/7 protein accumulation, but not with reduced PIN1/3/7 transcript levels. Additionally, Cd stabilized AXR3/IAA17 protein to repress auxin signalling in this Cd‐mediated process. Furthermore, decreasing Cd‐induced NO accumulation with either NO‐specific scavenger 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (cPTIO) or NO synthase inhibitor Nω‐nitro‐l‐Arg‐methylester (l‐NAME) compromised the Cd‐mediated inhibition of root meristem development, reduction in auxin and PIN1/3/7 accumulation, as well as stabilization of AXR3/IAA17, indicating that NO participates in Cd‐mediated inhibition of root meristem growth. Taken together, our data suggest that Cd inhibits root meristem growth by NO‐mediated repression of auxin accumulation and signalling in Arabidopsis.
Organophosphate flame retardants (OPFRs), used extensively as substitutes for polybrominated diphenyl ethers, are ubiquitous environmental contaminants. OPFR pollution in aquatic environments, the ...main sink of pollutants, has been studied extensively over the past decade. Here, we review the current knowledge on the consumption and applications of OPFRs, and on their ecotoxicity in aquatic environments worldwide. We also synthesize the available evidence on the occurrence of OPFRs in aquatic environments in China (wastewater treatment plant influent and effluent, surface water, sediment, aquatic biota, and drinking water). Across China, the measured concentrations of OPFRs differ by more than three orders of magnitude. Risk assessments based on these measurements indicate a low level of ecological risk from OPFRs in most aquatic environments in China, and a low risk to human health from drinking water and aquatic products. Finally, we identify gaps in the current knowledge and directions for further research on OPFRs in aquatic environments.
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•The ecotoxicity of OPFRs in aquatic environments were summarized.•Studies of OPFRs in aquatic environments in China were reviewed.•OPFRs were frequently detected in aquatic environments in China.•Ecological risk and human health risk of OPFRs in China's aquatic environments were low.•Knowledge gaps and research directions with OPFRs were identified.
An Empirical Study on API Usages Zhong, Hao; Mei, Hong
IEEE transactions on software engineering,
04/2019, Letnik:
45, Številka:
4
Journal Article
Recenzirano
API libraries provide thousands of APIs, and are essential in daily programming tasks. To understand their usages, it has long been a hot research topic to mine specifications that formally define ...legal usages for APIs. Furthermore, researchers are working on many other research topics on APIs. Although the research on APIs is intensively studied, many fundamental questions on APIs are still open. For example, the answers to open questions, such as which format can naturally define API usages and in which case, are still largely unknown. We notice that many such open questions are not concerned with concrete usages of specific APIs, but usages that describe how to use different types of APIs. To explore these questions, in this paper, we conduct an empirical study on API usages, with an emphasis on how different types of APIs are used. Our empirical results lead to nine findings on API usages. For example, we find that single-type usages are mostly strict orders, but multi-type usages are more complicated since they include both strict orders and partial orders. Based on these findings, for the research on APIs, we provide our suggestions on the four key aspects such as the challenges, the importance of different API elements, usage patterns, and pitfalls in designing evaluations. Furthermore, we interpret our findings, and present our insights on data sources, extraction techniques, mining techniques, and formats of specifications for the research of mining specifications.
Machine-assisted pathological recognition has been focused on supervised learning (SL) that suffers from a significant annotation bottleneck. We propose a semi-supervised learning (SSL) method based ...on the mean teacher architecture using 13,111 whole slide images of colorectal cancer from 8803 subjects from 13 independent centers. SSL (~3150 labeled, ~40,950 unlabeled; ~6300 labeled, ~37,800 unlabeled patches) performs significantly better than the SL. No significant difference is found between SSL (~6300 labeled, ~37,800 unlabeled) and SL (~44,100 labeled) at patch-level diagnoses (area under the curve (AUC): 0.980 ± 0.014 vs. 0.987 ± 0.008, P value = 0.134) and patient-level diagnoses (AUC: 0.974 ± 0.013 vs. 0.980 ± 0.010, P value = 0.117), which is close to human pathologists (average AUC: 0.969). The evaluation on 15,000 lung and 294,912 lymph node images also confirm SSL can achieve similar performance as that of SL with massive annotations. SSL dramatically reduces the annotations, which has great potential to effectively build expert-level pathological artificial intelligence platforms in practice.
...we combined the opinions of frontline epidemic control experts and reviewed the evidence in relevant literature. Two members of the evidence assessment team performed independent computer searches ...of English databases (PubMed, Ovid, Embase), Chinese databases (Chinese Biological Medical Literature database, China National Knowledge Infrastructure, Chinese Medical Journal Database), and relevant online website bulletins on COVID-19 (the World Health Organization, Elsevier, the Lancet, the New England Journal of Medicine, and the Journal of the American Medical Association, 2019 Novel Coronavirus Resource (2019nCoVR), and the Chinese Medical Journal Network). The search terms included the English terms and their Chinese equivalents: “novel coronavirus pneumonia,” “NCP,” “severe acute respiratory syndrome,” “SARS,” “Middle East Respiratory Syndrome,” “MERS,” “influenza,” “psychological therapy,” “guideline,” “statement,” “recommendation,” “randomized controlled trial,” and other rehabilitation-related English search terms and their Chinese equivalents included “respiratory rehabilitation,” “pulmonary rehabilitation,” “physiotherapy,” “physical therapy,” and “occupational therapy.” 11 Recommendations Intervention timing for respiratory rehabilitation in moderately ill patients Due to the limited understanding of the pathophysiological mechanisms of COVID-19, current clinical observations found that around 3% to 5% of moderately ill patients develop severe or even critical disease after 7 to 14 days of infection. ...the exercise intensity should not be too high as its objective is to maintain the existing physical status.
This study was designed to investigate the in vitro and in vivo antioxidant activities of inulin. The in vitro assays demonstrated that the antioxidant activities of inulin, including the DPPH ...radical scavenging activity, ABTS scavenging activity and ferric reducing power, were weak and significantly lower than those of Vitamin C (P < 0.05). The influence of dietary supplementation with inulin on the antioxidant status of laying hens was evaluated with in vivo antioxidant assays. The results indicated that inulin supplementation quadratically improved the egg production rate of the laying hens (P < 0.01). The antioxidant enzyme activities in the serum, including SOD, CAT, and GSH-Px, and the total antioxidant capacity increased quadratically as inulin levels increased (P < 0.001). The levels of MDA in the serum decreased quadratically as inulin levels increased (P < 0.001). These findings suggest that inulin has the potential to improve the antioxidant status of laying hens.
Objectives
LncRNA nuclear‐enriched abundant transcript 1 (NEAT1) participates in the development and progression of multiple malignancies. However, the molecular mechanism by which NEAT1 contributes ...to colorectal cancer (CRC) remains unclear.
Methods
The association between lncRNA NEAT1 expression and clinicopathological characteristics and prognosis in patients with CRC was analysed by TCGA RNA‐sequencing data. MTT, colony formation, flow cytometry, transwell assays and a xenograft tumour model were used to assess the functions of NEAT1. Bioinformatics and spearman correlation analysis were used to identify the NEAT1‐specific binding with miRNAs, and luciferase gene report and RIP assays were performed to confirm the interaction between miR‐193a‐3p (miR‐193a) and NEAT1 in CRC cells.
Results
Upregulation of NEAT1 expression was significantly correlated with TNM stage, poor survival and tumour recurrence in patients with CRC, and acted as an independent prognostic factor for tumour recurrence. Knockdown of NEAT1 suppressed cell proliferation, colony formation abilities and invasive potential and induced cell apoptosis, but overexpression of NEAT1 reversed these effects. Furthermore, NEAT1 was confirmed to act as a sponge of miR‐193a, and knockdown of NEAT1 attenuated miR‐193a inhibitor‐induced tumour promoting effects and L17RD expression in CRC cells. miR‐193a harboured negative correlation with NEAT1 and IL17RD expression in CRC specimens. In vivo experiment further validated the inhibitory effects of NEAT1 knockdown on xenograft tumour growth.
Conclusion
Our findings demonstrate that lncRNA NEAT1 acts as an oncogenic role in CRC cells by sponging miR‐193a and may represent a potential marker for CRC patients.
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