Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
1.
Phys Chem Chem Phys ; 26(15): 11429-11435, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38563510

RESUMO

The deposition and intercalation of metal atoms can induce superconductivity in monolayer and bilayer graphenes. For example, it has been experimentally proved that Li-deposited graphene is a superconductor with critical temperature Tc of 5.9 K, Ca-intercalated bilayer graphene C6CaC6 and K-intercalated epitaxial bilayer graphene C8KC8 are superconductors with Tc of 2-4 K and 3.6 K, respectively. However, the Tc of them are relatively low. To obtain higher Tc in graphene-based superconductors, here we predict a new Ca-intercalated bilayer graphene C2CaC2, which shows higher Ca concentration than the C6CaC6. It is proved to be thermodynamically and dynamically stable. The electronic structure, electron-phonon coupling (EPC) and superconductivity of C2CaC2 are investigated based on first-principles calculations. The EPC of C2CaC2 mainly comes from the coupling between the electrons of C-pz orbital and the high- and low-frequency vibration modes of C atoms. The calculated EPC constant λ of C2CaC2 is 0.75, and the superconducting Tc is 18.9 K, which is much higher than other metal-intercalated bilayer graphenes. By further applying -4% biaxial compressive strain to C2CaC2, the Tc can be boosted to 26.6 K. Thus, the predicted C2CaC2 provides a new platform for realizing superconductivity with the highest Tc in bilayer graphenes.

2.
Phys Chem Chem Phys ; 25(4): 2875-2881, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36625788

RESUMO

Monolayer biphenylene is a new two-dimensional (2D) carbon allotrope, which has been experimentally synthesized and theoretically predicted to show superconductivity. In this work, we investigate functionalized biphenylene with the adsorption of Li. The superconducting critical temperature (Tc) can be pushed from 0.59 K up to 3.91 K after Li adsorption. Our calculations confirm that the adsorption pushes the peak showing a high electronic density of states closer to the Fermi level, which usually leads to a larger Tc. Furthermore, the application of biaxial tensile strain can soften phonons and further enhance the Tc up to 15.86 K in Li-deposited biphenylene. Interestingly, a pair of type-II Dirac cones below the Fermi level has been observed, expanding the range of Dirac materials. It suggests that monolayer biphenylene deposited with Li may be a material with potential applications and improves the understanding of Dirac-type superconductors.

3.
Phys Chem Chem Phys ; 25(1): 580-589, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36484277

RESUMO

Theoretically and experimentally, MXenes consisting of Mo and C have aroused much interest due to superconductivity in their films and even monolayer forms. Here, based on first-principles calculations, we systematically calculate the electronic structure, phonon dispersion, and electron-phonon coupling (EPC) of monolayer Mo2C (both T- and H-phases), Mo3C2, and Mo3C3. The results show that H-MoxCy (x = 2 or 3, y = 1-3) always have lower total energies than their corresponding T phase and other configurations. All these two-dimensional (2D) molybdenum carbides are metals and some of them display weak phonon-mediated superconductivity at different superconducting transition temperatures (Tc). The Mo 4d-orbitals play a critical role in their electronic properties and the Mo atomic vibrations play a dominant role in their low-frequency phonons, EPC, and superconductivity. By comparison, we find that increasing the Mo content can enhance the EPC and Tc. Besides, we further explore the impact of strain engineering on their superconducting related physical quantities. With increasing biaxial stretching, the phonon dispersions are gradually softened to form some soft modes, which can trigger some peaks of α2F(ω) in the low-frequency region and evidently increase the EPC λ. The Tc of H-Mo2C can be increased up to 11.79 K. Upon further biaxial stretching, charge density waves may appear in T-Mo2C, H-Mo3C2, and H-Mo3C3.

4.
Ecotoxicol Environ Saf ; 243: 114011, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36007321

RESUMO

The combined contamination of heavy metals and microplastics is widespread in freshwater environments. However, there are few researches on their combined effects on aquatic plants. In this study, the effects of single and combined stress of 0.01 mg L-1 cadmium (Cd), 50 mg L-1 polyethylene and 50 mg L-1 polypropylene for 15 days on the physiological response, ultrastructure and rhizosphere microbial community of duckweed were investigated. The results showed that Cd and microplastics single or combined stress inhibited the growth of duckweed, shortened the root length and decreased the chlorophyll content. Compared with single Cd treatments, the combination of microplastics and Cd increased duckweed growth rate and increased superoxide dismutase activity and malondialdehyde content and reduced chloroplast structural damage, indicating that the combined stress could reduce the toxicity of heavy metals to duckweed. Through the study of rhizosphere microbial diversity, 1381 Operational Taxonomic Unit (OTUs) were identified and rich microbial communities were detected in the duckweed rhizosphere. Among them, the main microbial communities were Proteobacteria, Bacteroidetes, and Cyanobacteria. Compared with Cd single stress, the ACE and chao index of rhizosphere microbial community increased under combined stress, indicating that the diversity and abundance of microbial communities were improved after combined stress treatment. Our study revealed the effects of heavy metals and microplastics on aquatic plants, providing a theoretical basis for duckweed applications in complex water pollution.


Assuntos
Araceae , Metais Pesados , Microbiota , Poluentes do Solo , Cádmio/análise , Metais Pesados/toxicidade , Microplásticos , Plásticos , Rizosfera , Poluentes do Solo/análise
5.
BMC Anesthesiol ; 19(1): 237, 2019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31862004

RESUMO

BACKGROUND: The infusion of magnesium sulfate is well known to reduce arterial pressure and attenuate hemodynamic response to pneumoperitoneum. This study aimed to investigate whether different doses of magnesium sulfate can effectively attenuate the pneumoperitoneum-related hemodynamic changes and the release of vasopressin in patients undergoing laparoscopic gastrointestinal surgery. METHODS: Sixty-nine patients undergoing laparoscopic partial gastrectomy were randomized into three groups: group L received magnesium sulfate 30 mg/kg loading dose and 15 mg/kg/h continuous maintenance infusion for 1 h; group H received magnesium sulfate 50 mg/kg followed by 30 mg/kg/h for 1 h; and group S (control group) received same volume 0.9% saline infusion, immediately before the induction of pneumoperitoneum. Systemic vascular resistance (SVR), cardiac output (CO), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), serum vasopressin and magnesium concentrations were measured. The extubation time, visual analogue scale were also assessed. The primary outcome is the difference in SVR between different groups. The secondary outcome is the differences of other indicators between groups, such as CO, MAP, HR, CVP, vasopressin and postoperative pain score. RESULTS: Pneumoperitoneum instantly resulted in a significant reduction of cardiac output and an increase in mean arterial pressure, systemic vascular resistance, central venous pressure and heart rate in the control group (P <  0.01). The mean arterial pressure (T2 - T4), systemic vascular resistance (T2 - T3), central venous pressure(T3-T5) and the level of serum vasopressin were significantly lower (P <  0.05) and the cardiac output (T2 - T3) was significantly higher (P <  0.05) in group H than those in the control group. The mean arterial pressure (T4), systemic vascular resistance (T2), and central venous pressure(T3-T4) were significantly lower in group H than those in group L (P <  0.05). Furthermore, the visual analog scales at 5 min and 20 min, the level of vasopressin, and the dose of remifentanil were significantly decreased in group H compared to the control group and group L (P <  0.01). CONCLUSION: Magnesium sulfate could safely and effectively attenuate the pneumoperitoneum-related hemodynamic instability during gastrointestinal laparoscopy and improve postoperative pain at serum magnesium concentrations above 2 mmol/L. TRIAL REGISTRATION: The study was retrospectively registered at Chinese Clinical Trial Registry; the registration number is ChiCTR-IPD-17011145, principal investigator: D.Y. Q., date of registration: April 13, 2017.


Assuntos
Gastrectomia/métodos , Laparoscopia/métodos , Sulfato de Magnésio/administração & dosagem , Pneumoperitônio Artificial/métodos , Adulto , Idoso , Relação Dose-Resposta a Droga , Método Duplo-Cego , Hemodinâmica/efeitos dos fármacos , Hemodinâmica/fisiologia , Humanos , Sulfato de Magnésio/farmacocinética , Pessoa de Meia-Idade , Dor Pós-Operatória/epidemiologia , Pneumoperitônio Artificial/efeitos adversos , Vasopressinas/metabolismo
6.
Angew Chem Int Ed Engl ; 58(50): 18191-18196, 2019 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-31633856

RESUMO

Herein we described an efficient RhII -catalyzed enantioselective cyclopropenation reaction of internal alkynes with a masked difluorodiazoethane reagent (PhSO2 CF2 CHN2 , Ps-DFA). This asymmetric transformation offers efficient access to a broad range of enantioenriched difluoromethylated cyclopropenes (40 examples, up to 99 % yield, 97 % ee). The synthetic utility of obtained strained carbocycles is demonstrated by subsequent stereodefined processes, including cross-couplings, hydrogenation, Diels-Alder reaction, and Pauson-Khand reaction.

7.
Microbiol Spectr ; 12(8): e0334023, 2024 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-38980024

RESUMO

Vibrio vulnificus (Vv) is known to cause life-threatening infections, particularly septicemia. These patients often exhibit elevated levels of pro-inflammatory cytokines. While it is established that mitogen-activated protein kinase (MAPK)-interacting kinase (MNK) contributes to the production of pro-inflammatory cytokines, the role of MNK in macrophages during Vv infection remains unclear. In this study, we investigate the impact of MNK on macrophages. We demonstrate that the inhibition of MNK in J774A.1 cells, when treated with lipopolysaccharide or Vv, resulted in decreased production of tumor necrosis factor alpha and interleukin-6, without affecting their transcription. Interestingly, treatment with MNK inhibitor CGP57380 led to enhanced phosphorylation of MNK1 but decreased phosphorylation of eIF4E. Moreover, MNK1 knockout cells exhibited an increased capacity for phagocytosis and clearance of Vv, with more acidic phagosomes than the parental cells. Notably, CGP57380 did not impact phagocytosis, bacterial clearance, or phagosome acidification in Vv-infected J774A.1 cells. Considering the reported association between MNK and mammalian target of rapamycin complex 1 (mTORC1) activation, we investigated the mTORC1 signaling in MNK1 knockout cells infected with Vv. Our results revealed that attenuation of the mTORC1 signaling in these cells and treatment with the mTORC1 inhibitor rapamycin significantly enhanced bacterial clearance in J774A.1 cells following Vv infection. In summary, our findings suggest that MNK promotes the Vv-induced cytokine production in J774A.1 cells without affecting their transcription levels. MNK1 appears to impair the phagocytosis, bacterial clearance, and phagosome acidification in Vv-infected J774A.1 cells through the MNK1-mTORC1 signaling pathway rather than the MNK1-eIF4E signaling pathway. Our findings highlight the importance of the MNK1-mTORC1 pathway in modulating macrophage responses to Vv infection. IMPORTANCE: Mitogen-activated protein kinase (MAPK)-interacting kinase (MNK) plays a role in promoting the production of tumor necrosis factor alpha and interleukin-6 in macrophages during Vibrio vulnificus (Vv) infection. Inhibition or knockout of MNK1 in J774A.1 cells resulted in reduced cytokine production without affecting their transcription levels. MNK1 also impairs phagocytosis, bacterial clearance, and phagosome acidification in Vv-infected cells through the MNK1-mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. The findings highlight the importance of the MNK1-mTORC1 pathway in modulating macrophage responses to Vv infection.


Assuntos
Macrófagos , Alvo Mecanístico do Complexo 1 de Rapamicina , Fagocitose , Proteínas Serina-Treonina Quinases , Vibrio vulnificus , Vibrio vulnificus/metabolismo , Vibrio vulnificus/genética , Macrófagos/microbiologia , Macrófagos/imunologia , Macrófagos/metabolismo , Animais , Camundongos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Linhagem Celular , Vibrioses/imunologia , Vibrioses/microbiologia , Transdução de Sinais , Citocinas/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fosforilação , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Humanos , Compostos de Anilina , Purinas
8.
Nat Chem ; 16(3): 353-362, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38355829

RESUMO

Linkage chemistry and functional molecules derived from the stereogenic sulfur(VI) centre have important applications in organic synthesis, bioconjugation, drug discovery, agrochemicals and polymeric materials. However, existing approaches for the preparation of optically active S(VI)-centred compounds heavily rely on synthetic chiral S(IV) pools, and the reported linkers of S(VI) lack stereocontrol. A modular assembly method, involving sequential ligand exchange at the S(VI) centre with precise control of enantioselectivity, is appealing but remains elusive. Here we report an asymmetric three-dimensional sulfur(VI) fluoride exchange (3D-SuFEx) reaction based on thionyl tetrafluoride gas (SOF4). A key step involves the chiral ligand-induced enantioselective defluorinative substitution of iminosulfur oxydifluorides using organolithium reagents. The resulting optically active sulfonimidoyl fluorides allow for further stereospecific fluoride-exchange by various nucleophiles, thereby establishing a modular platform for the asymmetric SuFEx ligation and the divergent synthesis of optically active S(VI) functional molecules.

9.
Sci Total Environ ; 859(Pt 2): 160389, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36423841

RESUMO

Duckweed is a newly reported Cd hyperaccumulator that grow rapidly; however, little is known about its tolerance and detoxification mechanisms. In this study, we investigated the tissue, subcellular, and chemical form distribution of the Cd in duckweed and studied the influences of Cd on duckweed growth, ultrastructure, and rhizosphere microbial community. The results showed that Cd could negatively affect the growth of duckweed and shorten the root length. More Cd accumulated in the roots than in the leaves, and Cd was transferred from the roots to the leaves with time. During 12-24 h, Cd mainly existed in the cell wall fraction (2.05 %-95.52 %) and the organelle fraction (5.03 %-97.80 %), followed the soluble fraction (0.14 %-16.98 %). Over time, the proportion of Cd in the organelles increased (46.64 %-92.83 %), exceeding that in the cell wall (6.79 %-66.23 %), which indicated that duckweed detoxification mechanism may be related to the retention of cell wall and vacuole. The main chemical form of Cd was the NaCl-extracted state (30.15 %-88.66 %), which was integrated with pectate and protein. With increasing stress concentration and time, the proportion of the HCl-extracted state and HAc-extracted state increased, and they were low-toxic Cd oxalate and Cd phosphate, respectively. Cd damaged the ultrastructure of cells such as chloroplasts and mitochondria and inhibited the diversity of microbial communities in the duckweed rhizosphere; however, the dominant populations that could tolerate heavy metals increased. It was speculated that duckweed distributed Cd in a less toxic chemical form in a less active location, mainly through retention in the root cell wall and sequestration in the leaf vacuoles, and is dynamically adjusted. The rhizosphere microbial communities tolerate heavy metals may also be one of the mechanisms by which duckweed can tolerate Cd. This study revealed the mechanism of duckweed tolerance and detoxification of Cd at the molecular level and provides a theoretical basis for further development of duckweed.


Assuntos
Araceae , Metais Pesados , Microbiota , Cádmio/metabolismo , Rizosfera , Araceae/metabolismo , Metais Pesados/metabolismo , Raízes de Plantas/metabolismo
10.
Sci Total Environ ; 902: 166056, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37558073

RESUMO

Duckweed is a cadmium (Cd) hyperaccumulator. However, its enrichment characteristics and physiological responses to Cd have not been systematically studied. The physiological responses, enrichment characteristics, diversity of endophytic bacterial communities, and isolation of Cd-resistant endophytes in duckweed (Lemna minor 0014) were studied for different durations and Cd concentrations. The results indicated that peroxidase (POD) and catalase (CAT) activities decreased while superoxide dismutase activity first increased and then decreased with increasing Cd stress duration. POD activities, CAT activities, and O2- increased as Cd concentrations increased. Malondialdehyde content and Cd accumulation in duckweed increased with increasing concentrations and time. This endophytic diversity study identified 488 operational taxonomic units, with the dominant groups being Proteobacteria, Firmicutes, and Actinobacteria. Paenibacillus sp. Y11, a strain tolerant to high concentrations of Cd and capable of significantly promoting duckweed growth, was isolated from the plant. Our study revealed the effects of heavy metals on aquatic plants, providing a theoretical basis for the application of duckweed in water pollution.


Assuntos
Araceae , Metais Pesados , Paenibacillus , Poluentes do Solo , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/farmacologia
11.
Chem Sci ; 14(31): 8401-8407, 2023 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-37564418

RESUMO

Herein, a triphenylamine derivative (TP-3PY) possessing 4-(4-bromophenyl)pyridine (PY) as an electron-accepting group and tris[p-(4-pyridylvinyl)phenyl]amine (TPA) with large two-photon absorption cross-sections as an electron-donating group was obtained, and showed intense absorption in the visible light region (λmax = 509 nm) and weak near-infrared (NIR) fluorescence emission at 750 nm. After complexation with cucurbit[8]uril (CB[8]), TP-3PY showed bright NIR fluorescence emission at 727 nm and phosphorescence emission at 800 nm. When the supramolecular assembly (TP-3PY⊂CB[8]) further interacted with dodecyl-modified sulfonatocalix[4]arene (SC4AD), the fluorescence and phosphorescence emissions were further enhanced at 710 and 734 nm, respectively. However, only the fluorescence emission of TP-3PY was enhanced in the presence of cucurbit[7]uril (CB[7]) and SC4AD. More interestingly, the photoluminescence of TP-3PY⊂CB[8]@SC4AD and TP-3PY⊂CB[7]@SC4AD assemblies could be excited by both visible (510 nm) and NIR light (930 nm). Finally, these ternary supramolecular assemblies with bright NIR light emission were applied to lysosome imaging of tumor cells and real-time biological imaging of mice.

12.
Infect Drug Resist ; 15: 6471-6483, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36353378

RESUMO

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has proven to be difficult to control and typically presents with devastating effects. Methods: This retrospective study was conducted on the renal recipients at our institution between January 2021 to January 2022. Clinical data was collected to identify factors associated with CRKP infection and clinical outcomes. Results: There were 104 cases out of 186 total renal recipients who presented with at least one infection within 3 months after KT, and 14 cases developed unfavorable clinical outcomes. We identified 16 confirmed CRKP infected cases with the incidence of 8.60%. Possible donor derived infection (DDI) (OR = 6.743; 95% CI: 1.477-30.786; P = 0.014) were independent risk factors for the occurrence of CRKP infection of renal recipients in our analysis, CRKP infection (OR = 20.723; 95% CI: 3.448-124.547; P = 0.001) and pneumonia (OR = 28.458; 95% CI: 1.956-413.984 P = 0.014) were independent risk factors for the occurrence of unfavorable clinical outcomes following KT, and the occurrence of unfavorable clinical outcomes following KT were significantly associated with CRKP infection (r = 0.535; P < 0.001) and antibiotic regimen containing ceftazidime/avibactam (CZA) (r = -0.655; P = 0.006). The use of CZA was significantly different in the comparison of antibiotic regimens between the CRKP infected renal recipients with unfavorable outcomes and CRKP infected patients with favorable outcomes. Conclusion: It is possible that DDI can lead to CRKP infection, and CRKP infection and pneumonia were closely correlated with poor prognosis. The use of CZA may play a role in avoiding the unfavorable outcomes of CRKP infected recipients.

13.
Infect Drug Resist ; 15: 4899-4906, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36060233

RESUMO

Background: Potent immune-suppressive therapy has been demonstrated to increase the risk of infective endocarditis (IE) in renal recipients. Reports of Corynebacterium striatum (C. striatum) endocarditis in renal recipients are scarce, thus limiting understanding of the disease. Case Presentation: We describe a case of native valve endocarditis caused by C. striatum in a 35-year-old male patient. The young man with end-stage renal failure underwent kidney transplantation because of autosomal dominant polycystic kidney disease. Ceftazidime was administered after the surgery according to routine procedures, and the patient was discharged on the 14th day after the surgery without any evidence of infection. The patient experienced fever on the 56th day, and Corynebacterium was cultured from the patient's blood, in agreement with the results of testing of the donor kidney preservation solution. On the 64th day, multiple thromboses were found in the right external iliac artery, particularly around the anastomotic orifice of the transplanted renal artery. Vegetation was found in the posterior mitral valve tip on the 65th day. The patient had symptoms of persistent angina pectoris and chest tightness and underwent mitral valve replacement and vegetative resection. The patient eventually died. C. striatum was detected in the mitral valve and vegetation tissue with metagenomic next-generation sequencing. Conclusion: C. striatum may cause endocarditis and endanger patients' lives and thus warrants greater attention. Genotypic assays such as metagenomic next-generation sequencing are demonstrated to be effective in confirming species identity. Adequate anti-infection therapy and early surgery are required after IE is discovered.

14.
Biology (Basel) ; 10(6)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204395

RESUMO

The heavy metal cadmium (Cd), as one of the major environmentally toxic pollutants, has serious impacts on the growth, development, and physiological functions of plants and animals, leading to deterioration of environmental quality and threats to human health. Research on how plants absorb and transport Cd, as well as its enrichment and detoxification mechanisms, is of great significance to the development of phytoremediation technologies for ecological and environmental management. This article summarises the research progress on the enrichment of heavy metal cadmium in plants in recent years, including the uptake, transport, and accumulation of Cd in plants. The role of plant roots, compartmentalisation, chelation, antioxidation, stress, and osmotic adjustment in the process of plant Cd enrichment are discussed. Finally, problems are proposed to provide a more comprehensive theoretical basis for the further application of phytoremediation technology in the field of heavy metal pollution.

15.
Biomolecules ; 11(1)2021 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-33450858

RESUMO

Recently, plant bioreactors have flourished into an exciting area of synthetic biology because of their product safety, inexpensive production cost, and easy scale-up. Duckweed is the smallest and fastest-growing aquatic plant, and has advantages including simple processing and the ability to grow high biomass in smaller areas. Therefore, duckweed could be used as a new potential bioreactor for biological products such as vaccines, antibodies, pharmaceutical proteins, and industrial enzymes. Duckweed has made a breakthrough in biosynthesis as a chassis plant and is being utilized for the production of plenty of biological products or bio-derivatives with multiple uses and high values. This review summarizes the latest progress on genetic background, genetic transformation system, and bioreactor development of duckweed, and provides insights for further exploration and application of duckweed.


Assuntos
Araceae/metabolismo , Reatores Biológicos , Pesquisa/tendências , Araceae/genética , Araceae/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Transformação Genética
16.
Org Lett ; 22(19): 7762-7767, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-32966087

RESUMO

Cyano-tetrazole is the first reported compound that bears four nitrogen atoms in a single five-membered ring. This unique molecular scaffold has long been ignored after its discovery in 1885, mainly attributed to the scarcity of available synthetic methods. Indeed, the most popular approach to tetrazoles (that is the cycloaddition reaction between nitriles and azides) has inevitably excluded the possibility of introducing valuable cyano groups to decorate the final heterocyclic cores. Here, we describe a completely different disconnection strategy to the long time-pursued cyano-tetrazoles via a simple, direct, and practical cycloaddition transformation between readily accessible aryl diazonium salts and diazoacetonitrile. This method provides both regioisomers of disubstituted tetrazoles from the same set of starting materials in a metal cation controlled fashion.

17.
Front Cell Infect Microbiol ; 10: 596609, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33585271

RESUMO

Vibrio vulnificus (V. vulnificus) is an estuarine bacterium that is capable of causing rapidly fatal infection in humans. Proper polarization and bactericidal activity of macrophages play essential roles in defending against invading pathogens. How macrophages limit V. vulnificus infection remains not well understood. Here we report that tuberous sclerosis complex 1 (TSC1) is crucial for the regulation of V. vulnificus-induced macrophage polarization, bacterial clearance, and cell death. Mice with myeloid-specific deletion of TSC1 exhibit a significant reduction of survival time after V. vulnificus infection. V. vulnificus infection induces both M1 and M2 polarization. However, TSC1 deficient macrophages show enhanced M1 response to V. vulnificus infection. Interestedly, the absence of TSC1 in myeloid cells results in impaired bacterial clearance both in vivo and in vitro after V. vulnificus infection. Inhibition of the mammalian target of rapamycin (mTOR) activity significantly reverses V. vulnificus-induced hypersensitive M1 response and resistant bactericidal activity both in wild-type and TSC1-deficient macrophages. Moreover, V. vulnificus infection causes cell death of macrophages, possibly contributes to defective of bacterial clearance, which also exhibits in a mTORC1-dependent manner. These findings highlight an essential role for the TSC1-mTOR signaling in the regulation of innate immunity against V. vulnificus infection.


Assuntos
Esclerose Tuberosa , Vibrioses , Animais , Macrófagos , Camundongos , Proteína 1 do Complexo Esclerose Tuberosa
18.
Front Cell Dev Biol ; 8: 587961, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33117816

RESUMO

The marine bacterium Vibrio vulnificus causes potentially fatal bloodstream infections, typically in patients with chronic liver diseases. The inflammatory response and anti-bacterial function of phagocytes are crucial for limiting bacterial infection in the human hosts. How V. vulnificus affects macrophages after phagocytosis is unclear. In this report, we found that the bactericidal activity of macrophages to internalize V. vulnificus was dependent on mammalian target of rapamycin (mTOR) and NOD-like receptor (NLR) family pyrin domain containing 3 (NLRP3) interaction. Additionally, the NLRP3 expression was dependent on mTORC1 activation. Inhibited mTORC1 or absence of NLRP3 in macrophages impaired V. vulnificus-induced phagosome acidification and phagolysosome formation, leading to a reduction of intracellular bacterial clearance. mTORC1 signaling overactivation could increase NLRP3 expression and restore insufficient phagosome acidification. Together, these findings indicate that the intracellular bactericidal activity of macrophages responding to V. vulnificus infection is tightly controlled by the crosstalk of NLRP3 and mTOR and provide critical insight into the host bactericidal activity basis of clearance of V. vulnificus through lyso/phagosome.

19.
Org Lett ; 21(20): 8244-8249, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31513413

RESUMO

We report a general and efficient approach to construct achiral and chiral gem-difluoroallylic amines from a masked difluorodiazo reagent (PhSO2CF2CHN2) and readily available imines. This facile protocol takes advantage of the phenylsulfonyl and diazo moieties as efficient activating and directing groups to assist difluoroalkyl incorporation and facilitate the chemodivergent and stereoselective formation of gem-difluoroallylic amines.

20.
PLoS One ; 12(7): e0181454, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28719654

RESUMO

Vibrio vulnificus (V. vulnificus), a Gram-negative marine bacterium, can cause life-threatening primary septicemia, especially in patients with liver diseases. How V. vulnificus affects the liver and how it acts on macrophages are not well understood. In this report, we demonstrated that V. vulnificus infection causes a strong inflammatory response, marked expansion of liver-resident macrophages, and liver damage in mice. We demonstrated further that V. vulnificus activates mTOR in macrophages and inhibition of mTOR differentially regulates V. vulnificus induced inflammatory responses, suggesting the possibility of targeting mTOR as a strategy to modulate V. vulnificus induced inflammatory responses.


Assuntos
Macrófagos/metabolismo , Macrófagos/microbiologia , Serina-Treonina Quinases TOR/metabolismo , Vibrio vulnificus/fisiologia , Animais , Ativação Enzimática , Inflamação/microbiologia , Células de Kupffer/citologia , Fígado/imunologia , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Neutrófilos/citologia , Vibrioses/complicações
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA