A first example of low-energy blue-light-mediated formal Doyle–Kirmse reaction for gem-difluoroallylation of aryl diazoesters has been developed. A variety of highly functionalized gem-difluoroallyl ...containing esters bearing transformable sulfur and bromine groups were efficiently assembled with broad substrate scope under mild, catalyst-free, and additive-free conditions. The reaction represents a practical and environmentally friendly approach for C–CF2 bond formation based on rearrangement strategy, which will find potential applications among drug discovery and development.
Leave the metal out: Arylboronates are produced in moderate to good yields by direct borylation of readily available aryl amines (see scheme). The reaction can be carried out under air at room ...temperature and transition‐metal catalysis is not required. The boronate products can be used without purification in Suzuki–Miyaura cross‐coupling reactions.
Cascade reactions (also known as domino reactions) are arguably the most powerful means to achieve the construction of multiple ring systems in a single step. In this Tutorial Review, highlights in ...cascade polycyclizations applied to natural product syntheses over the last five years are discussed, including pericyclic, ionic, metal-catalyzed, organocatalytic, and radical processes. Significant developments in each of these fields that have advanced the state-of-the-art are a particular focus, including photochemical and electrochemical methods, novel biomimetic routes, and enantioselective cascades.
Cascade reactions are among the most powerful means to achieve the construction of multiple ring systems in a single step. This tutorial review describes recent advances in the use of polycyclization cascades in natural product synthesis.
In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, 51 surface sediment samples (0–4 cm) were collected in the Zhoushan Islands ...coastal sea of the East China Sea (ECS). The heavy metal concentrations, grain size and total organic carbon (TOC) contents of these surface sediments were comprehensively analyzed. The results showed that the order of the average concentrations of heavy metals is Zn > Cr > Cu > Pb > As > Cd > Hg. Zn, Cr, Cd and Hg exhibit similar distribution and which derived from a common source, however, Cu, Pb and As present different distribution. The metal enrichment factor (EF) and geoaccumulation index (Igeo) values both suggest that Cu and Cd likely pose environmental risks. The results of this study could provide scientific data to authorities in charge of sustainable marine management.
•The spatial distribution characteristics of seven heavy metals were comprehensively analyzed.•The sources of the seven heavy metal elements in the Zhoushan Islands coastal sea area are different.•The contaminant level of Cr, Zn, Cd, Hg and Pb in the study area is moderate, but the Cu and Cd pose environment risks.
An operationally simple Ag(I)-catalyzed approach for the synthesis of isoquinoline and quinazoline fused 1,2,3-triazoles was developed by a condensation and amination cyclization cascade of ...amino-NH-1,2,3-triazoles with 2-alkynylbenzaldehydes involving three new C-N bond formations in one manipulation, in which the group of -NH of the triazole ring serves as a nucleophile to form the quinazoline skeleton. The efficient protocol can be applied to a variety of substrates containing a range of functional groups, delivering novel pentacyclic fused 1,2,3-triazoles in good-to-excellent yields.
Background: Tumor PD-L1 levels have predictive value in PD-1/PD-L1 checkpoint blockade therapies, yet biopsies can only provide baseline information. Whether PD-L1 expression on circulating tumor ...cells (CTCs) could serve as an alternative biomarker is of great interest.
Design: We established an immunofluorescence assay for semi-quantitative assessment of the PD-L1 expression levels on CTCs with four categories (PD-L1
negative
, PD-L1
low
, PD-L1
medium
and PD-L1
high
). 35 patients with different advanced gastrointestinal tumors were enrolled in a phase 1 trial of a PD-1 inhibitor, IBI308. The CTC numeration and the PD-L1 expression levels were analyzed.
Results: Prior the treatment of IBI308, 97% (34/35) patients had CTCs, ranging from1 to 70 (median 7). 74% (26/35) had PD-L1
positive
CTCs, and 60% (21/35) had at least one PD-L1
high
CTCs. The disease control (DC) rate in PD-L1
high
patients (48%) is much higher than the others (14%). The group with at least 20% abundance of PD-L1
high
CTCs had even higher DC rate of 64% (9/14), with only 14% DC rate for the rest (3/21). We also observed that the count changes of total CTC, PD-L1
postive
CTC and PD-L1
high
CTC correlate quite well with disease outcome (P<0.001, P = 0.002 and 0.007, respectively). In addition, the abundance of PD-L1
high
CTCs at baseline had predicative significance for progression free survival (PFS).
Conclusions: We revealed that the abundance of PD-L1
high
CTCs at baseline might serve as a predictor to screen patients for PD-1/PD-L1 blockade therapies and measuring the dynamic changes of CTC could indicate the therapeutic response at early time.
Programmed death-1 receptor (PD-1) and its ligand (PD-L1) play an integral role in regulating the immune response against cancer. This study investigated the prognostic significance of PD-L1 ...expression on tumor cells and tumor-infiltrating immune cells (TILs) in the tumor microenvironment in Chinese patients with esophageal squamous cell carcinoma (ESCC). Archival formalin-fixed, paraffin-embedded ESCC samples from treatment-naïve patients with ESCC after surgery or by diagnostic endoscopic biopsy were collected between 2004 and 2014. Expression of PD-L1 in ESCC tumor specimens was assessed by immunohistochemistry (IHC), and the degree of TIL infiltration was evaluated by examining hematoxylin and eosin-stained (H&E) specimens. PD-L1+ as defined as ≥1% of tumor cell membranes showing ≥1+ intensity. In 428 patients, specimens from 341 (79.7%) were PD-L1+. In the definitive treatment group (patients who received curative esophagectomy or definitive chemo-radiation therapy), PD-L1 positivity was associated with a significantly shorter DFS and OS. In the palliative chemotherapy group exhibited, neither PFS nor OS correlated significantly with PD-L1 expression. PD-L1 expression was positively associated with TIL density. In 17 paired tumor tissues collected before and after treatment, an increase in PD-L1 expression was associated with disease progression, whereas a decrease in PD-L1 expression was associated with response to chemotherapy or disease control. So, PD-L1 expression was associated with a significantly worse prognosis in patients with ESCC. These observations suggest that PD-L1 may play a critical role in ESCC cancer progression and provide a rationale for developing PD-L1 inhibitors for treatment of a subset of ESCC patients.
Corn straw is an abundant lignocellulose resource and by-product of agricultural production. With the continuous increase in agricultural development, the output of corn straw is also increasing ...significantly. However, the inappropriate disposal of straw results in wasting of resources, and also causes a serious ecological crisis. Screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. For this purpose, our research group isolated three actinomycete strains with efficient lignocellulose degradation ability from soil in the cold region of China:
sp. G1
,
sp. G2
and
sp. G3
. Their microbial properties and taxonomic status were assessed to improve our understanding of these strains. The three strains showed typical characteristics of the genus
, and likely represent three different species. Genome functional annotation indicated that most of their genes were related to functions like carbohydrate transport and metabolism. In addition, a similar phenomenon also appeared in the COG and CAZyme analyses, with a large number of genes encoding carbohydrate-related hydrolases, such as cellulase, glycosidase and endoglucanase, which could effectively destroy the structure of lignocellulose in corn straw. This unambiguously demonstrated the potential of the three microorganisms to hydrolyze macromolecular polysaccharides at the molecular level. In addition, in the straw-returning test, the decomposing consortium composed of the three
isolates (G123) effectively destroyed the recalcitrant bonds between the various components of straw, and significantly reduced the content of active components in corn straw. Furthermore, microbial diversity analysis indicated that the relative abundance of
, reportedly associated with soil antibiotic resistance and antibiotic degradation, was significantly improved with straw returning at both tested time points. The microbial diversity of each treatment was also dramatically changed by supplementing with G123. Taken together, G123 has important biological potential and should be further studied, which will provide new insights and strategies for appropriate treatment of corn straw.
Purpose
The highly efficient degradation bacteria were selected from the humus from the very cold straw in China for many years to construct the in situ degradation bacteria, and the degradation ...efficiency of corn straw was determined by process optimization.
Methods
According to the main components of corn straw, through morphological, physiological, and biochemical screening, three highly efficient complementary degradation strains were selected to construct the compound flora, and the degradation efficiency was analyzed by Fourier transform infrared spectrometer, field emission scanning electron microscope, and X-ray diffractometer.
Result
The corn straw selected in this paper is mainly composed of cellulose (31.99%), hemicellulose (25.33%), and lignin (14.67%). Through the determination of enzyme activity, strain
Streptomyces
sp. G1
T
has high decomposition ability to cellulose and hemicellulose but weak utilization ability to lignin; strain
Streptomyces
sp. G2
T
has the strongest decomposition ability to cellulose and hemicellulose among the three strains. The decomposition ability of strain
Streptomyces
sp. G3
T
to lignin was the strongest among the three strains. Therefore, by compounding the three strains, the decomposition ability has been greatly improved. The optimal process conditions obtained by single factor and response surface method are as follows: pH is 7, temperature is 30 °C, inoculation amount is 5%, rotational speed is 210 rpm, and the weight loss rate of straw is 60.55% after decomposing for 7 days. A large amount of degradation of corn straw can be seen by Fourier transform infrared spectrometer, field emission scanning electron microscope, and X-ray diffractometer.
Conclusion
Streptomyces
sp. G1
T
,
Streptomyces
sp. G2
T
, and
Streptomyces
sp. G3
T
screened from straw humus in very cold areas were used to construct in situ degradation bacteria, which had good straw degradation activity and had the potential to be used for straw treatment in cold areas after harvest. This characteristic makes the complex bacteria become a strong competitive candidate for industrial production, and it is also an effective biotechnology in line with the current recycling of resources.
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