Aymmetric Aza-Friedel-Crafts Reaction of Isatin-Derived Ketimines with Indoles Catalyzed by a Chiral Phase-Transfer Catalyst

A highly enantioselective aza-Friedel-Crafts reaction of 1H-indoles with isatin-derived N-Cbz-ketimines catalyzed by quinine-derived phase-transfer catalysts was developed. A series of chiral 3-aminobisindole compounds containing a tetrasubstituted stereocenter were constructed by this protocol in high yields (82-91%) and moderate to excellent enantioselectivities (46-94% ee).

Correction: Direct analysis of metabolites in the liver tissue of zebrafish exposed to fiproles by internal extractive electrospray ionization mass spectrometry

Correction for ‘Direct analysis of metabolites in the liver tissue of zebrafish exposed to fiproles by internal extractive electrospray ionization mass spectrometry’ by Jun Liu et al., Analyst, 2021, 146, 4480–4486, https://doi.org/10.1039/D1AN00490E.

Internal extractive electrospray ionization mass spectrometry for investigating the phospholipid dysregulation induced by perfluorooctanoic acid in Nile tilapia

Direct profiling of endogenous biomolecules in tissue samples is considered to be a promising approach to investigate metabolic-related toxicity in organisms induced by emerging pollutants.

[Clinicopathological features of verrucous hemangioma]

Objective: To investigate the clinicopathological features, and differential diagnosis of verrucous hemangioma (VH). Methods: Twenty-eight VH cases diagnosed from 2005 to 2020 in Henan Provincial People's Hospital, Zhengzhou, China were analyzed retrospectively. Immunohistochemical studies were used to detect diagnostic markers. The mutation status of PIK3CA (exons 9 and 20) was detected using fluorescence PCR. Results: There were 13 males and 15 females in 28 cases, with the male to female ratio of 1.0∶1.2. There were 25 patients under the age of 18 years. The age range was from 10 months to 56 years (mean, 9.7 years; median, 4.5 years). There were 17 cases occurred in the lower extremities, 7 in the upper extremities and 4 in the trunk. All 28 cases were irregular red patches on the skin, which grew slowly. Some of them were thickened with uneven surface, which was light pink or red-white. Skin lesions of the 7 cases ranged from dark red and reddish brown, with a rough and hard surface. Satellite foci were present. Microscopically, 28 cases had a wide range of pathological features. Dilated, malformed vessels were observed from dermal papilla to deep soft tissue. Among them, the dermal papillary layer was mainly composed of many proliferating and expanding thin-walled capillaries and cavernous blood vessels. Thin-walled small vessels were found in the dermal reticular layer and subcutaneous fascia layer, with no obvious endothelial cell proliferation, occasional papillary hyperplasia, and lobular distribution of the malformed vessels in the fascia layer mixed with the fibroadipose tissue. There was epidermal papillary hyperplasia with hyperkeratosis and parakeratosis, lengthening and mutual fusion of epithelial horns. Immunohistochemistry showed that CD31, CD34, ERG and WT-1 were diffusely and strongly positive. The expression of GLUT-1 was present in superficial dermal vascular endothelial cells, but undetectable in the deep layer. The PIK3CA tests of 13 cases showed that no somatic mutations were found in exons 9 and 20. Twenty-five patients were followed up for 5 months to 10 years. Seven patients underwent multiple surgical resections and plastic surgeries due to the large size, and 8 patients had recurrence. Conclusions: VH is a rare congenital vascular malformation and more commonly occurs in infants and children. It tends to appear in limbs, especially lower limbs and distal limbs. Its morphology and immunophenotype are characteristic and should be distinguished from other vascular malformations and the resolution phase of infant hemangiomas. In about one third of the cases, postoperative recurrence may occur and long-term follow-up is often required.

Robust bulk micro-nano hierarchical copper structures possessing exceptional bactericidal efficacy

Conventional copper (Cu) metal surfaces are well recognized for their bactericidal properties. However, their slow bacteria-killing potency has historically excluded them as a rapid bactericidal material. We report the development of a robust bulk superhydrophilic micro-nano hierarchical Cu structure that possesses exceptional bactericidal efficacy. It resulted in a 4.41 log₁₀ reduction (>99.99%) of the deadly Staphylococcus aureus (S. aureus) bacteria within 2 min vs. a 1.49 log₁₀ reduction (96.75%) after 240 min on common Cu surfaces. The adhered cells exhibited extensive blebbing, loss of structural integrity and leakage of vital intracellular material, demonstrating the rapid efficacy of the micro-nano Cu structure in destructing bacteria membrane integrity. The mechanism was attributed to the synergistic degradation of the cell envelope through enhanced release and therefore uptake of the cytotoxic Cu ions and the adhesion-driven mechanical strain due to its rapid ultimate superhydrophilicity (contact angle drops to 0° in 0.18 s). The scalable fabrication of this micro-nano Cu structure was enabled by integrating bespoke precursor alloy design with microstructure preconditioning for dealloying and demonstrated on 2000 mm² Cu surfaces. This development paves the way to the practical exploitation of Cu as a low-cost antibiotic-free fast bactericidal material.

[Oxymatrine improves renal fibrosis and inflammation in diabetic rats by modulating CHK1/2 phosphorylation]

OBJECTIVE

To explore the role of cell cycle checkpoint kinase 1/2 (CHK1/2) in mediating the inhibitory effect of oxymatrine (OMT) against renal inflammation and fibrosis in diabetic rats.

METHODS

SD rats were randomly divided into normal control group, diabetes model group (DM) and OMT treatment group (n=6). HE and Masson staining were used to observe histopathological changes of the renal tissue, and the expressions of CHK1, CHK2, p-CHK1 and p-CHK2 were localized by immunohistochemical staining. The contents of interleukin-6 (IL-6) and IL-1β in the renal tissue were detected using ELISA, and the expression levels of CHK1, CHK2, p-CHK1, p-CHK2, type Ⅲ collagen (Col-Ⅲ), type Ⅳ collagen (Col-Ⅳ), and fibronectin (FN) were determined using Western blotting. The changes in the expressions of CHK1, CHK2, p-CHK1, p-CHK2, Col-Ⅲ, Col-Ⅳ and FN proteins were also examined with Western blotting in NRK-52E cells in response to high glucose exposure, OMT treatment and siRNA-mediated CHK1/2 knockdown.

RESULTS

In diabetic rats, OMT treatment significantly decreased the levels of blood glucose, serum creatinine and 24 h urinary protein (P < 0.05) and obviously improved inflammatory cell infiltration and fibrosis phenotype in the renal tissue (P < 0.05). CHK1 and CHK2 were mainly expressed in the cytoplasm and nuclei of renal tubule cells, and their phosphorylation levels were significantly higher in DM group than in the control group and OMT group. OMT treatment significantly decreased the protein expression levels of p-CHK1, p-CHK2, Col-Ⅲ, Col-Ⅳ and FN in the renal tissue of diabetic rats and in NRK-52E cells exposed to high glucose (P < 0.05). In NRK-52E cells, CHK1/2 knockdown resulted in significant reduction of the protein expressions of p-CHK1/2, Col-Ⅲ, Col-Ⅳ and FN (P < 0.05).

CONCLUSION

The inhibitory effects of OMT against renal inflammation and fibrosis in diabetic rats are mediated probably by lowered phosphorylation levels of CHK1 and CHK2, which result in reduced release of the downstream inflammatory mediators and decreased secretion and deposition of extracellular matrix.

[MiR-671-5p negatively regulates SMAD3 to inhibit migration and invasion of osteosarcoma cells]

OBJECTIVE

To explore the role of miR-671-5p in regulating the migration and invasion of osteosarcoma and the underlying mechanisms.

METHODS

The differentially expressed microRNAs (miRNAs) in osteosarcoma were screened in the NCBI online database, and the target proteins of these miRNAs were predicted and their functions were analyzed. Osteosarcoma cells were transfected with a plasmid overexpressing miR-671-5p, and the transfection efficiency was assessed using quantitative real-time PCR (qRT-PCR). The changes in the migration and invasion of the transfected cells were examined with Transwell assay, and the expressions of proteins related with epithelial-mesenchymal transition (EMT) were detected using Western blotting. Dual-luciferase reporter assay was performed to determine whether the 3'UTR of SMAD3 contained a targeted binding site of miR-671-5p.

RESULTS

MiR-671-5p was significantly down-regulated in both osteosarcoma tissues and osteosarcoma cells (P < 0.05). The osteosarcoma cells overexpressing miR-671-5p showed significantly reduced migration and invasion abilities (P < 0.05) with obviously lowered expressions of EMT-related proteins (P < 0.05). SMAD3 was highly expressed in osteosarcoma cells (P < 0.05), and dual-luciferase reporter assay confirmed the presence of a targeted binding site between miR-671-5p and the 3'UTR of SMAD3 (P < 0.05). In osteosarcoma cells transfected with a SMAD3-overexpressing plasmid (P < 0.05), the high expression of SMAD3 significantly inhibited by miR-671-5p overexpression (P < 0.05). Transwell assay demonstrated that SMAD3 overexpression significantly promoted the migration and invasion of osteosarcoma cells (P < 0.05), and while miR-671-5p overexpression obviously reversed this effect (P < 0.05).

CONCLUSION

MiR-671-5p can inhibit the invasion and migration of osteosarcoma cells by negatively regulating SMAD3.

Asymmetric Synthesis of 3-Phenyl-2,3-dihydro-1H-pyrrolo[3,2-b]pyridine-3-carbonitriles Catalyzed by Phase-Transfer Catalyst Derived from tert-Leucine

Chiral phase-transfer catalysts derived from tert-leucine were synthesized and used in the asymmetric synthesis of 4-azaindoline derivatives. By this method, both enantiomers of the corresponding products were obtained in excellent yield (up to 99%) with high enantio­selectivities (up to 91% ee) and diastereoselectivities (up to >99: 1 dr).

Melatonin protects against excessive autophagy-induced mitochondrial and ovarian reserve function deficiency though ERK signaling pathway in Chinese hamster ovary (CHO) cells

Excessive autophagy-induced follicular atresia of ovarian granulosa cells might be one of the pathogenesis of Premature Ovarian Insufficiency (POI), and melatonin (MT) exerted many beneficial effects on mitochondria. However, there was little report regarding the beneficial effects of MT on excessive autophagy-induced mitochondrial and ovarian reserve function deficiency, and the mechanisms have not been clearly identified. Autophagy played a protective role in cells survival, however, high level of autophagy could lead to cell death. In this report, firstly, Chinese hamster ovary cell damage model stably expressing EGFP-LC3 was established. Next, we systematically investigated the protective effects of MT on mitochondrial and ovarian reserve function and molecular mechanisms using this cell damage model. Our results revealed that 10^-9 M MT not only protected against the decline of anti-mullerian hormone (AMH) expression induced by excessive autophagy, but also rescued excessive autophagy-induced impairment of mitochondrial expression and mitochondrial membrane potential. Furthermore, MT protected against excessive autophagy-induced decrease of nucleus-encoded proteins including SDHA and mitofilin, and mitochondrial dynamic-related proteins including OPA1, MFN2, and DRP1. MT also decreased mitochondrial oxidative stress, increased antioxidant enzyme superoxide dismutase 2 (SOD2) expression and ameliorated the G2/M cell cycle arrest induced by excessive autophagy. Finally, MT inhibited excessive autophagy-induced activation of extracellular signal regulated kinase (ERK) signaling pathway. In conclusion, our study showed that MT rescued impairment of mitochondrial and ovarian reserve function, and production of mitochondrial ROS and cell cycle arrest induced by excessive autophagy through down-regulated ERK pathway, implying the potential therapeutic drug target for POI.

Micromagnetic simulation of microstructure effect for binary-main-phase Nd-Ce-Fe-B magnets

We investigate the magnetic properties of a chemically heterogeneous binary-main-phase (BMP) Nd-Ce-Fe-B magnet with a core-shell structure via micromagnetic simulation. It is found that the coercivity strongly depends on the shell thickness. The BMP magnet's coercivity initially increases and then decreases with increasing Nd-rich shell thickness, and so there is the optimal shell thickness which shows the maximum coercivity for any given Ce concentration. The simulation shows the significant difference in coercivity and maximum energy product between the BMP and single-main-phase magnets. Notably, the magnetization reversal mechanism of the BMP magnet is revealed in the simulation. Local reversals in the BMP magnet first occur in the Ce-rich shells, followed by the Nd-rich cores. Then, the magnetization in Ce-rich core/Nd-rich shell typed grains is switched after reversed magnetization of all the Nd-rich core/Ce-rich shell typed grains. The BMP magnet represents a further increased coercivity for a larger GB thickness, which can be well explained by a maximum stray field.

[Design, screening and antibacterial activity evaluation of the novel antibacterial peptide KR-1]

OBJECTIVE

To design novel antimicrobial peptides with high activity and low toxicity and evaluate their effect against Streptococcus mutans and other oral bacteria for prevention and treatment of dental caries.

OBJECTIVE

We synthesized two antimicrobial peptides (KR-1 and KR-2) using Dhvar4 (a histatins5 mimic) as the template. The antimicrobial peptides with high activity and low toxicity were screened using minimal inhibitory concentration (MIC) test, hemolysis test, and CCK-8 assay. Streptococcus mutans biofilms cultured in 96-well plates were divided into experimental group (KR-1) and positive control group (CHX) and treated with concentration gradients (0.6×, 0.8×, 1× and 2× MICs) of KR-1 and CHX, respectively. Crystal violet staining was used for quantitative analysis of the changes of the biofilms after the treatments. The structural changes of the biofilms were observed with laser confocal microscopy after KR-1 treatment at 10 × MIC. The antimicrobial activity of KR-1 against oral Streptococcus was analyzed based on the time required for sterilization after KR-1 treatment.

OBJECTIVE

The MIC of KR-1 and KR-2 for S. mutans was 3.2 μmol/L and 12.8 μmol/L, respectively. Under the effective concentration, KR-1 and KR-2 resulted in hemolysis rates of 0.35% and 48.8% in rabbit red blood cells and lowered the survival rates of gingival fibroblasts to 88.7% and 21.94%, respectively. KR-1 treatment significantly reduced biofilm formation with a minimum biofilm inhibition concentration (MBIC₅₀) lower than 1.92 μmol/L, and showed an even stronger antimicrobial than CHX at the concentration of 2.56 μmol/L (P=0.001). Confocal laser scanning microscopy revealed that the biofilm structure became loosened after KR-1 treatment, which was capable of killing about 90% of the bacteria within 5 min.

OBJECTIVE

The antimicrobial peptide KR-1 has a stronger antibacterial activity and a low toxicity with a good inhibitory effect against S. mutans biofilm.

Direct analysis of metabolites in the liver tissue of zebrafish exposed to fiproles by internal extractive electrospray ionization mass spectrometry

Exploring the metabolic disturbance of fipronil and its derivatives in aquatic organisms may provide a more comprehensive understanding of the impact of fipronil on the ecological environment. In this work, internal extractive electrospray ionization mass spectrometry (iEESI-MS) was used to directly analyze metabolites in the liver tissue of zebrafish exposed to fipronil and its three derivatives. Partial least squares-discriminant analysis (PLS-DA) revealed that 32 signals were considered as differential signals in zebrafish after the exposure treatment of fipronil and its derivatives, including phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs), phosphatidylethanolamines (PEs), fatty acids and so on. The pathway analysis result showed that both fipronil and its derivatives have a significant impact on the glycerophospholipid metabolism of zebrafish. Besides, the intensities of PC signals in the liver samples of each group showed such a trend: mixed fiprole exposed group > fipronil sulfone exposed group ≈ fipronil sulfide exposed group > fipronil exposed group > fipronil desulfinyl exposed group > control group, indicating that mixed exposure of fipronil and its derivatives exhibited more significant metabolic disturbance in zebrafish. Taken together, iEESI-MS is applied to environmental toxicology and investigating the metabolic disturbance induced by fipronil and its derivatives in aquatic organisms, providing a new analytical method for this field.

InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards

Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth-system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ47) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ47 and Δ47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ47 (I-CDES) values for Intercarb-Carbon Dioxide Equilibrium Scale.

[Analysis for the breast cancer screening among urban population in Hebei province, 2018-2019]

From 2018 to 2019, 3 453 cases of high-risk population were screened by the Cancer Screening Program in Urban China (CanSPUC) in Hebei Province, with the age of (53.94±8.00). 147 and 686 cases of breast cancer positive and suspicious positive patients were found, with the positive rate and suspicious positive rate of 4.26% and 19.87% respectively. The suspicious positive rate of 45-49 years old age group was the highest (28.32%), and the positive rate of over 70 years old age group was the highest (7.32%). The positive detection rate of mammography combined with ultrasound was 5.16%, which was higher than that of ultrasound alone (2.46%) (χ²=30.28,P<0.001) or mammography alone (3.06%) (χ²=14.56,P<0.001).

Potential health risks of metals in skin care products used by Chinese consumers aged 19-29 years

Metal contamination of skin care products that occurs during their production poses potential health risks, which are of increasing concern, to consumers. Here, we collected 570 responses to an online survey to analyze the usage pattern of skin care products across China. Then a total of 30 commonly used skin care products with various prices and applications were purchased. The concentrations of metals (Al, Zn, Cu, Ni, Cr, Pb, Hg, and Cd) and metalloid As, were determined. Next, we improved the frequency calculation method and used the weighted exposure frequency to calculate the dermal absorption dose (DAD). The amounts of Zn, Cr, and Al that were assimilated by the human body via uptake were approximately 2 orders of magnitude greater than those of Pb, Hg, Cd, Ni and metalloid As. In addition, younger consumers were at higher risk of metals exposure than older consumers because of their higher frequency of use of skin care products. Al and Zn posed higher risk to consumers because of its high DAD. There was no significant chronic non-carcinogenic health risk (hazard index < 1) posed by skincare product use.