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1.
J Nanosci Nanotechnol ; 20(4): 2442-2451, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492260

RESUMO

Two methods of TiO2 addition were applied to prepare hydroxyapatite/TiO2 (HA/TiO2) composite, i.e., in-situ hydrolysis TiO2 in HA powders (N-HA/TiO2) and mixing commercial nano-sized HA and TiO2 powder (C-HA/TiO2). Effects of TiO2 addition methods and sintering temperatures on phase, microstructure and microhardness were investigated for pressureless sintered HA/TiO2 composites, and pure HA was investigated for comparison. Results show that TiO2 from both in-situ hydrolysis and mixing commercial powder presented similar effects on phase structures and composition, and trended to chemically react with HA in the HA/TiO2 composites at high sintering temperature. Weight loss for different composites was investigated by thermal analysis. Sintering behavior for two different composite was also discussed. The TiO2 from in-situ hydrolysis can effectively enhance the TiO2 distribution and densification for the N-HA/TiO2 composites. Both two different composites showed typical grain growth and pore formation with the increase of sintering temperature. The N-HA/TiO2 composite had a lower porosity, higher shrinkage and microhardness than that of C-HA/TiO2 composite at sintering temperature from 700 °C to 1100 °C.

2.
J Nanosci Nanotechnol ; 20(3): 1685-1696, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492331

RESUMO

The process in which the nanofiber membrane is used to remove heavy metal ions and separation of oil-water solution is analyzed. Herein, smooth structures are induced by rGO-g-PAO sheets, which could be attributed to the strong interaction between P(AN-MA) and rGO-g-PAO. It is rewarding to note that the P(AN-MA)/rGO-g-PAO nanofiber membrane would exhibit superhydrophilic traits in the air and ultra-low oil-adhesive traits underwater when the concentration of P(AN-MA) and PAO is 13 wt.% and 0.3 wt.%, respectively. The amidoxime (-C(NH2) NOH) groups on the membrane surface can efficiently adsorb copper (Cu(II)) (1.65 mmol/g) and chromium (Cr(VI)) (4.70 mmol/g) ions in the waste water. Meanwhile, the P(AN-MA)/rGO-g-PAO nanofiber membrane exhibits ultrahigh flux (~6150 LMH), satisfying rejection rate (~97%) and outstanding flux recovery ratio (~99%) in separating oil water emulsion.

3.
Appl Opt ; 58(27): 7311-7318, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31674375

RESUMO

Precision glass molding (PGM) has become a viable processing method for large-volume aspheric optical elements. The optimization of a PGM process is an obstacle to the realization of mass production. The current work is focused on optimizing the process parameters to gain satisfactory surface shape. But the machining cycle time is not optimized. When setting the process route in the machine interface, going to the next step after reaching the target temperature rather than reaching the target time is usually set for the heating and cooling phase. Thus, the time to complete the heating and cooling stages of the production cycle is known only in the actual production. As for chalcogenide glass, its physical and chemical properties are greatly dependent on temperature. So, it is necessary to effectively simulate these stages to obtain the cost in time for actual production. Due to the excellent availability of numerical simulation, the rapid development of computing technology, and the increase of task scale in data and information processing, the finite element method can be applied to simulate the whole molding process. In this paper, a heat transfer model is established with the partial differential equation toolbox in MATLAB software. MSC.Marc software is used to simulate the heating stage at the same time. The numerical results are consistent, indicating that the heat transfer model established in MATLAB is, at least to a certain extent, valid. The heat transfer model needs further improvement by considering temperature-dependent properties such as viscoelasticity to make it a more effective tool for process analysis and optimization.

4.
J Cell Physiol ; 2019 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-31587299

RESUMO

Apoptosis is the major cause of cardiomyocyte death in myocardial ischemia/reperfusion injury (MI/RI). Increasing evidence suggests that microRNAs (miRNAs) can contribute to the regulation of cardiomyocytes apoptosis by posttranscriptional modulation of gene expression networks. However, the effects of miR-327 in regulating MI/RI-induced cardiomyocytes apoptosis have not been extensively investigated. This study was performed to test whether miR-327 participate in cardiomyocytes apoptosis both in vitro and in vivo, and reveal the potential molecular mechanism of miR-327 regulated MI/RI through targeting apoptosis repressor with caspase recruitment domain (ARC). Sprague-Dawley (SD) rats were subjected to MI/RI by left anterior descending coronary artery occlusion for 30 min and reperfusion for 3 hr. H9c2 cells were exposed to hypoxia for 4 hr and reoxygenation for 12 hr to mimic I/R injury. miRNA-327 recombinant adenovirus vectors were transfected into H9c2 cells for 48 hr and rats for 72 hr before H/R and MI/RI treatment, respectively. The apoptosis rate, downstream molecules of apoptotic pathway, and the target reaction between miRNA-327 and ARC were evaluated. Our results showed that miR-327 was upregulated and ARC was downregulated in the myocardial tissues of MI/RI rats and in H9c2 cells with H/R treatment. Inhibition of miR-327 decreased the expression levels of proapoptotic proteins Fas, FasL, caspase-8, Bax, cleaved caspase-9, cleaved caspase-3, and the release of cytochrome-C, as well as increasing the expression levels of antiapoptotic protein Bcl-2 via negative regulation of ARC both in vivo or vitro. In contrast, overexpression miR-327 showed the reverse effect. Moreover, the results of luciferase reporter assay indicated miR-327 targets ARC directly at the posttranscriptional level. Taken together, inhibition of miR-327 could attenuate cardiomyocyte apoptosis and alleviate I/R-induced myocardial injury via targeting ARC, which offers a new therapeutic strategy for MI/RI.

5.
Sensors (Basel) ; 19(21)2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31652845

RESUMO

Groundwater dynamic monitoring of assessment points and evaluation areas has a significant predictive effect for controlling the occurrence of disasters. Obtaining water level and water temperature change data can provide important theoretical significance and reference values. However, in some remote areas of China, the measurement data concerning water level change are mostly obtained by manual measurement. This measurement method not only wastes manpower, but also cannot ensure the accuracy and real-time nature of the data. Therefore, this paper carried out research and design on a fluviograph, based on the relationship between hydraulic pressure and water depth. In the paper, the fluviograph used ultra-small pressure sensors to complete the data acquisition of the water level, a STM32L011 single-chip microcomputer (STMicroelectronics, Geneva, Switzerland) to process the data, and LabVIEW software to display the final data. Additionally, the water level data record and water temperature information record can be fed back to the user and the manager. After laboratory testing, the water level variation error range of this fluviograph was 1-2 cm, and the water temperature error range was less than 1 °C, which indicates the accuracy of the metrical data. The results show that the fluviograph realizes the function of automatically recording the water level and water temperature of the monitoring point, and it improves the social production efficiency greatly.

6.
J Am Coll Nutr ; : 1-19, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31625814

RESUMO

Objective: Our objective was to synthesize both trial and observational studies and undertake a meta-analysis to explore the associations between calcium from dietary and supplemental intakes and cardiovascular disease (CVD) risks. Methods: Data sources were from PubMed, Cochrane Central, Scopus, and Web of Science, published from the inception dates up to March 2019. Randomized controlled trials (RCTs) and prospective cohort studies with data on dietary or supplemental intake of calcium, with or without vitamin D, and cardiovascular outcomes, were included. Results: Of the 1,212 identified studies, 26 prospective cohort studies and 16 RCTs were included. Results of cohort studies reveled that dietary calcium intakes (DCIs) ranging from 200 to 1500 mg/d did not affect the risk of CVD, coronary heart disease (CHD), and stroke (relative risk (RR) RR for CVD = 0.96, 95% CI, 0.87-1.05; RR for CHD = 0.98, 95% CI, 0.88-1.08; RR for stroke = 0.94, 95% CI, 0.85-1.04). Pooled RR of RCTs showed that the risk of CHD due to calcium supplements (CSs) increased 8% (RR = 1.08, 95% CI, 1.02-1.22; I2 = 0.0%) and increased 20% allocated to CSs alone (RR = 1.20, 95% CI, 1.08-1.33; I2 = 0.0%). CSs increased the risk of myocardial infarction (MI) by 14% (RR = 1.14, 95% CI, 1.05-1.25; I2 = 0.0%), and CSs alone increased the MI risk 21% (RR = 1.21, 95% CI, 1.08-1.35; I2 = 0.0%). Conclusions: We concluded that calcium intake from dietary sources do not adequately increase the risk of CVD including CHD and stroke, while calcium supplements might raise CHD risk, especially MI.

7.
Artigo em Inglês | MEDLINE | ID: mdl-31595612

RESUMO

Tremendous energy consumption is required for traditional artificial N2 fixation, leading to additional environmental pollution. Recently, new Li-N2 batteries have inextricably integrated energy storage with N2 fixation. In this work, graphene is introduced into Li-N2 batteries and enhances the cycling stability. However, the instability and hygroscopicity of the discharge product Li3 N lead to a rechargeable but irreversible system. Moreover, strong nonpolar N≡N covalent triple bonds with high ionization energies also cause low efficiency and irreversibility of Li-N2 batteries. In contrast, the modification with in situ generated Li3 N and LiOH restrained the loss and volume change of Li metal anodes during stripping and plating, thereby promoting the rechargeability of the Li-N2 batteries. The mechanistic study here will assist in the design of more stable Li-N2 batteries and create more versatile methods for N2 fixation.

8.
J Dermatol ; 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31646683

RESUMO

Acne keloidalis (AK) is one of the primary cicatricial alopecias and predominantly affects men of African descent. Reports in Asians are scant. This study aimed to retrospectively review the clinical and histopathological features of AK patients in southern Taiwan and identify the pathognomonic features of AK. There were 15 patients with histopathologically confirmed AK in National Cheng Kung University Hospital between 1988 and 2018. The median onset age was 24 years (range, 14-71). The male : female ratio was 14:1. In the acute stage of AK, the lymphocytic and neutrophilic peri-infundibular inflammatory infiltrates with microabscess formation and edema corresponded to the clinical finding of isolated papules or pustules. Subsequently, the inflammatory infiltrates involved the mid-dermis and the isthmus of hair follicles. The "spade sign", a thin and dilated space resembling the shape of a balloon or spade symbol of playing cards at the level of lower isthmus, was identified in eight biopsies from five patients and may be a pathognomonic sign in the subacute stage of AK. At the chronic stage, the segments of hair shafts remained in the upper to mid-dermis and induced chronic inflammation and extensive fibrosis, resulting in the clinical keloid-like appearance. The restriction of inflammation and fibrosis in the upper to mid-dermis was another unique and pathognomonic feature of AK.

9.
Plant Cell ; 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31615848

RESUMO

Under nutrient and energy-limiting conditions, plants up-regulate sophisticated catabolic pathways such as autophagy to remobilize nutrients and restore energy homeostasis. Autophagic flux is tightly regulated under these circumstances through the autophagy-related (ATG)-1 kinase complex, which relays upstream nutrient and energy signals to the downstream components that drive autophagy. Here, we investigated the role(s) of the Arabidopsis ATG1 kinase during autophagy through an analysis of a quadruple mutant deficient in all four ATG1 isoforms. These isoforms appear to act redundantly, including the plant-specific, truncated ATG1t variant, and like other well-characterized atg mutants, homozygous atg1abct plants display early leaf senescence and hypersensitivity to nitrogen and fixed-carbon starvation. Although the ATG1 kinase is essential for up-regulating autophagy under nitrogen deprivation and short-term carbon starvation, it did not stimulate autophagy under prolonged carbon starvation. Instead, an ATG1-independent response arose requiring the phosphatidylinositol-3-phosphate (PI3K) and Sucrose-Non-Fermenting Kinase (SnRK)-1 kinases, possibly through phosphorylation of the ATG6 subunit within the PI3K complex by the catalytic KIN10 subunit of SnRK1. Together, our data connect the ATG1 kinase to autophagy, and reveal that plants engage multiple pathways to activate autophagy during nutrient stress, which include the ATG1 route as well as an alternative route requiring SnRK1 and ATG6 signaling.

10.
J Infect Chemother ; 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31575500

RESUMO

Bacteremia is associated with high morbidity and mortality, which contribute substantially to health care costs. A beneficial influence of appropriate empirical antimicrobial therapy (EAT) on patient outcome is evidenced; However, the evidence highlighting a comparison of clinical manifestations and of the effects of inappropriate EAT between Gram-positive and Gram-negative bacteremia is insufficient. In a retrospective 6-year cohort study, the total 2053 adults (Gram-positive, 566; Gram-negative 1487) presenting with community-onset monomicrobial aerobes bacteremia were recruited. Inappropriate EAT was defined as the first dose of an appropriate antimicrobial agent not being administered within the first 24 h after blood cultures were drawn. Although the bacteremia severity (a Pitt bacteremia score) at onset, comorbidity severity (the McCabe-Johnson classification), and 28-day mortality rate were similar in the two groups. Furthermore, after adjustment of independent predictors of 28-day mortality respectively recognized by the multivariate regression model in Gram-negative and Gram-positive groups, the Kaplan-Meier curve and Cox regression analysis revealed a significant difference (adjust odds ratio [AOR], 2.68; P < 0.001) between appropriate and inappropriate EAT in the Gram-negative group, but not in the Gram-positive group (AOR, 1.54; P = 0.06). Conclusively, patients with Gram-positive and Gram-negative bacteremia exhibited the similar presentation in bacteremia severity, but a greater impact of inappropriate EAT on survival of patients with Gram-negative aerobe bacteremia was evidenced.

11.
J Mater Chem B ; 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31608921

RESUMO

Identifying cancer at the cellular level during an early stage offers the hope of greatly improved outcomes for cancer patients. As potential cancer biomarkers, nitroreductase (NTR) and human quinine oxidoreductase 1 (hNQO1) are overexpressed in many type of cancer cells. Simultaneous detection of these two biomarkers would benefit diagnostic precision in related cancers without yielding false positive results. Herein, based on a dye generated in situ strategy, a dual-enzyme-responsive probe, CNN, was rationally designed and synthesized by installing p-nitrobenzene and trimethyl-locked quinone propionic acid groups, which are specific for NTR and hNQO1, respectively, into a single fluorophore. This probe is only activated in the presence of both NTR and hNQO1 and produces a large fluorescence response, enabling the detection of both endogenous NTR and hNQO1 activity in living cells. The imaging results indicate that the CNN probe differentiates cancer cells (HeLa, MDA-MB-231 and HepG2 cells) from normal liver HL-7702 cells owing to the existence of relatively high endogenous levels of both biomarkers in these cancer cells.

12.
Org Lett ; 21(20): 8323-8327, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31584285

RESUMO

A novel strategy to trap iminyl radicals with copper ions has been developed at room temperature, the resulted high-valent Cu(III) imine intermediate resets quickly to form nitrene and then to furnish a 2H-azirine. This protocol with dual copper/photoredox catalyst enables the selective imination of unactivated C-H bonds under mild conditions with a broader scope. Moreover, this method also uncovers a novel ring-expansion rearrangement from cyclobutyl oxime derivatives to give the α-acylamino cyclopentanones.

13.
Nat Commun ; 10(1): 4861, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31649241

RESUMO

Achieving the activation of drugs within cellular systems may provide targeted therapies. Here we construct a tumour-selective cascade activatable self-detained system (TCASS) and incorporate imaging probes and therapeutics. We show in different mouse models that the TCASS system accumulates in solid tumours. The molecules show enhanced accumulation in tumour regions via the effect of recognition induced self-assembly. Analysis of the molecular penetration in tumour tissue shows that in vivo self-assembly increases the penetration capability compared to typical soft or hard nanomaterials. Importantly, the in vivo self-assembled molecules exhibit a comparable clearance pathway to that of small molecules, which are excreted from organs of the reticuloendothelial system (liver and kidney), while are relatively slowly eliminated from tumour tissues. Finally, this system, combined with the NIR probe, shows high specificity and sensitivity for detecting bladder cancer in isolated intact patient bladders.

14.
Biomed Res Int ; 2019: 2457964, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31662971

RESUMO

Given the lack of research on the schoolchildren exposure to PM2.5-bound PHAs in northeast China, we investigated the effects of exposure to ambient benzo[b]fluoranthene (BbFA) and dibenz[a,h]anthracene (DahA) bound to PM2.5 on pulmonary ventilation dysfunction (PVD) and small airway dysfunction (SAD). PM2.5 samples at two schools (A and B) were collected, and the concentrations of PM2.5-bound 4-6-ring PAHs were analyzed. PVD and SAD were evaluated by pulmonary function tests in 306 students while urinary MDA and CRP levels were measured. The results confirmed that ambient PM2.5-bound 4-6-ring PHA levels were significantly higher and the PVD and SAD incidence in schools A and B were increased during the heating season. We found that PM2.5-bound BbFA, BkFA, BaP, and DahA levels were only correlated with SAD in schoolchildren; the correlation coefficients of BbFA and DahA were the highest effect estimates, possibly due to altered MDA levels. Therefore, this research enables us to better understand the effects of exposure to ambient PM2.5-bound PHAs on pulmonary function parameters. Our results also showed that identification of hazardous PM2.5-bound BbFA and DahA to health is crucial for preventing the respiratory-related diseases.

15.
Artigo em Inglês | MEDLINE | ID: mdl-31628084

RESUMO

AIM: To clarify the gross anatomy structure of the check ligament of the palpebra superior in relation to congenital blepharoptosis operation. METHOD: Seven fixed and three fresh cadavers of Chinese adults (between 53 and 76 years old; 5 males and 5 females) were used. Gross dissection was performed on fourteen eyes in seven cadavers. In three fixed cadavers, six bulbus oculi received histological sections for immunohistochemical tests. RESULT: Below the levator upon the superior rectus, the check ligament described by Lockwood is found. It extends bilaterally and attaches to the orbital wall behind the inner and lateral canthus tendon. Between the inferior obliquus and the inferior rectus, we also found a sheath structure similar to the check ligament extending bilaterally to the orbital wall. These two structures form an annular fascial system surrounding the eyeball. The medial half of the fascial sheath is tenacious, and the immunohistochemical test proves that smooth muscle cells are found in this part. CONCLUSION: We call this whole fascial sheath surrounding the circumocular muscle the Extraocular Check Ligament System (ECLS), and it plays a restricting and checking role in the movement of the eyeball. Surgeons should be aware of the ECLS when performing ptosis or other blepharal surgery.

16.
BMC Nephrol ; 20(1): 363, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31590637

RESUMO

BACKGROUND: Patients receiving maintenance hemodialysis (HD) and peritoneal dialysis (PD) are frequently hospitalized. Reducing unplanned 30-day hospital readmissions is a key priority for improving the quality of health care. The purpose of this study was to assess the association between the Charlson Comorbidity Index (CCI), which has been used to evaluate multi-comorbidities status, and 30-day readmission in patients on HD and PD therapy. METHODS: The Hospital Quality Monitoring System (HQMS), a national administrative database for hospitalized patients in China was used to extract dialysis patients admitted from January 2013 to December 2015. The outcome was the unplanned readmission following the hospital discharge within 30 days. For patients with multiple hospitalizations, a single hospitalization was randomly selected as the index hospitalization. A cause-specific Cox proportional hazard model was utilized to assess the association of CCI with readmission within 30 days. RESULTS: Of the 124,721 patients included in the study, 19,893 patients (16.0%) were identified as experiencing unplanned readmissions within 30 days. Compared with patients without comorbidity (CCI = 2, scored for dialysis), the risk of 30-day readmission increased with elevated CCI score. The hazards ratio (HR) for those with CCI 3-4, 5-6 and > 6 was 1.01 (95% confidence interval [CI] 0.98-1.05), 1.09 (95% CI 1.05-1.14), and 1.14 (95% CI 1.09-1.20), respectively. CONCLUSIONS: Our study indicated that CCI was independently associated with the risk of 30-day readmission for patients receiving dialysis including HD and PD, and could be used for risk-stratification.

17.
Int J Biol Sci ; 15(10): 2156-2169, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31592233

RESUMO

Recently there has been an increasing interest in bioactive factors with robust osteogenic ability and angiogenesis function to repair bone defects. However, previously tested factors have not achieved satisfactory results due to low loading doses and a short protein half-life. Finding a validated stable substitute for these growth factors and apply it to the construction of porous scaffolds with the dual function of osteogenesis and angiogenesis is therefore vital for bone tissue regeneration engineering. Graphene oxide (GO) has attracted increasing attention due to its good biocompatibility, osteogenic, and angiogenic functions. This study aims to design a scaffold composed of mesoporous bioactive glasses (MBG) and GO to investigate whether the composite porous scaffold promotes local angiogenesis and bone healing. Our in vitro studies demonstrate that the MBG-GO scaffolds have better cytocompatibility and higher osteogenesis differentiation ability with rat bone marrow mesenchymal stem cells (rBMSCs) than the purely MBG scaffold. Moreover, MBG-GO scaffolds promote vascular ingrowth and, importantly, enhance bone repair at the defect site in a rat cranial defect model. The new bone was fully integrated not only with the periphery but also with the center of the scaffold. From these results, it is believed that the MBG-GO scaffolds possess excellent osteogenic-angiogenic properties which will make them appealing candidates for repairing bone defects. The novelty of this research is to provide a new material to treat bone defects in the clinic.

18.
Sci Rep ; 9(1): 14500, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601858

RESUMO

Bacteremia is associated with high morbidity and mortality, but the utility and optimal timing of follow-up blood cultures (FUBCs) remain undefined. To assess the optimal timing of FUBCs related to appropriate antibiotic therapy (AAT), adults with community-onset bacteremia and FUBCs after bacteremia onset were retrospectively studied during the 6-year period in two hospitals. Based on the time gap between the initiation of AAT and FUBC sampling, 1,247 eligible patients were categorized as FUBCs prior to AAT (65 patients, 5.2%), 0-3 days (202, 16.2%), 3.1-6 days (470, 37.7%), 6.1-9 days (299, 24.0%), and ≥9 days (211, 16.9%) after AAT. The prognostic impact of the growth of the same bacteria in FUBCs on 30-day mortality was evidenced only in patients with FUBCs at 3.1-6 days after AAT (adjusted odds ratio [AOR], 3.75; P < 0.001), not in those with FUBCs prior to AAT (AOR, 2.86; P = 0.25), 0-3 days (AOR, 0.39; P = 0.08), 6.1-9 days (AOR, 2.19; P = 0.32), and ≥9 days (AOR, 0.41; P = 0.41) of AAT, after adjusting independent factors of 30-day mortality recognized by the multivariable regression in each category. Conclusively, persistent bacteremia in FUBCs added prognostic significance in the management of adults with community-onset bacteremia after 3.1-6 days of AAT.

19.
Elife ; 82019 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-31625906

RESUMO

Medial and lateral hypothalamic loci are known to suppress and enhance appetite, respectively, but the dynamics and functional significance of their interaction have yet to be explored. Here we report that, in larval zebrafish, primarily serotonergic neurons of the ventromedial caudal hypothalamus (cH) become increasingly active during food deprivation, whereas activity in the lateral hypothalamus (LH) is reduced. Exposure to food sensory and consummatory cues reverses the activity patterns of these two nuclei, consistent with their representation of opposing internal hunger states. Baseline activity is restored as food-deprived animals return to satiety via voracious feeding. The antagonistic relationship and functional importance of cH and LH activity patterns were confirmed by targeted stimulation and ablation of cH neurons. Collectively, the data allow us to propose a model in which these hypothalamic nuclei regulate different phases of hunger and satiety and coordinate energy balance via antagonistic control of distinct behavioral outputs.

20.
Molecules ; 24(20)2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31640286

RESUMO

Many essential oils (EOs) regulate the quorum-sensing (QS) system of pathogens and inhibit the virulence expression. Interference with QS can potentially reduce bacterial multidrug resistance and aid the biological control of bacterial disease. In the present work, the antibacterial and anti-QS activities of Cinnamomum camphora leaf EO were investigated. A total of 23 chemical components with relative levels ≥0.11%, including a large number of terpene compounds, were identified in C. camphora leaf EO by gas chromatography-mass spectrometry (GC-MS). The principal component was linalool, followed by eucalyptol, with relative levels of 51.57% and 22.07%, respectively. The minimum inhibitory concentration (MIC) and antibacterial activity of C. camphora EO were examined, and P. aeruginosa and E. coli ATCC25922 showed the highest and lowest sensitivity to C. camphora EO, respectively. Tests of QS inhibitory activity revealed that C. camphora EO significantly decreased the production of violacein and biofilm biomass in C. violaceum, with the maximum inhibition rates of 63% and 77.64%, respectively, and inhibited the biofilm formation and swarming movement, independent of affecting the growth of C. violaceum. Addition of C. camphora EO also resulted in downregulation of the expression of the acyl-homoserine lactones (AHL) synthesis gene (cviI) and transcription regulator (cviR), and inhibited the expression of QS-regulated virulence genes, including vioA, vioB, vioC, vioD, vioE, lasA, lasB, pilE3, and hmsHNFR. Collectively, the prominent antibacterial activity and anti-QS activities clearly support that C. camphora EO acts as a potential antibacterial agent and QS inhibitor in the prevention of bacterial contamination.

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