Study on Antibacterial and Quorum-Sensing Inhibition Activities of Cinnamomum camphora Leaf Essential Oil.

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.

Prediction of all-cause death and specific causes of death in patients with gastric cancer with liver metastasis: a Surveillance, Epidemiology, and End Results-based study.

BACKGROUND: Gastric cancer (GC), considered the fifth most prevalent malignancy, is the fourth leading cause of cancer death worldwide. This cancer is heterogeneous and invasive and often metastasizes to the liver. The survival of patients with GC, especially cancer-specific survival (CSS), is a matter of concern to their families and medical workers in clinical practice. However, efficient tools for early risk prediction are lacking. Thus, this study aimed to develop a nomogram for forecasting the overall survival (OS) and CSS of patients with GC with liver metastasis (GCLM) based on the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: Information on individuals with GCLM was acquired from the SEER database from January 2000 to December 2015. Patients' data were randomized into the train cohort and the test cohort. The independent factors for CSS and OS were determined by univariate and multivariate competing risk analyses and Cox proportional hazards analysis, and the nomograms for predicting CSS and OS were constructed. The receiver operating characteristic curve and calibration curve were used to measure the accuracy and calibration of nomograms. RESULTS: Our study included 4372 patients with GCLM, with 3060 patients in the train set and 1312 in the test set. The mean follow-up period was 12.31 months. The independent factors influencing the OS of patients with GCLM were age, bone metastasis, chemotherapy, grade, lung metastasis, stage, primary site, radiotherapy, surgical primary site, T stage, and tumor size. The concordance Index (C-index) of the constructed nomogram for OS were 0.718 (SE, 0.004) in the train set and 0.0.680 (SE, 0.006) in the test set. The independent factors affecting the CSS of patients with GCLM were age, chemotherapy, grade, lung metastasis, stage, radiotherapy, regional lymph node positive, surgical primary site, and total number of tumors. The C-index for the constructed nomogram for CSS were 0.696 (SE, 0.005) in the train set and 0.696 (SE, 0.008) in the test set. CONCLUSION: The constructed nomograms showed satisfactory performance in predicting the OS and CSS of patients with GCLM, which can help clinicians formulate follow-up and rehabilitation strategies conducive to survival. At the same time, it can provide more family and social support for high-risk groups.

The Role of MbEGS1 and MbEGS2 in Methyleugenol Biosynthesis by Melaleuca bracteata.

Many aromatic plant volatile compounds contain methyleugenol, which is an attractant for insect pollination and has antibacterial, antioxidant, and other properties. The essential oil of Melaleuca bracteata leaves contains 90.46% methyleugenol, which is an ideal material for studying the biosynthetic pathway of methyleugenol. Eugenol synthase (EGS) is one of the key enzymes involved in the synthesis of methyleugenol. We recently reported two eugenol synthase genes (MbEGS1 and MbEGS2) present in M. bracteata, where MbEGS1 and MbEGS2 were mainly expressed in flowers, followed by leaves, and had the lowest expression levels in stems. In this study, the functions of MbEGS1 and MbEGS2 in the biosynthesis of methyleugenol were investigated using transient gene expression technology and virus-induced gene silencing (VIGS) technology in M. bracteata. Here, in the MbEGSs genes overexpression group, the transcription levels of the MbEGS1 gene and MbEGS2 gene were increased 13.46 times and 12.47 times, respectively, while the methyleugenol levels increased 18.68% and 16.48%. We further verified the function of the MbEGSs genes by using VIGS, as the transcript levels of the MbEGS1 and MbEGS2 genes were downregulated by 79.48% and 90.35%, respectively, and the methyleugenol content in M. bracteata decreased by 28.04% and 19.45%, respectively. The results indicated that the MbEGS1 and MbEGS2 genes were involved in the biosynthesis of methyleugenol, and the transcript levels of the MbEGS1 and MbEGS2 genes correlated with the methyleugenol content in M. bracteata.

Analysis on Deflection of Projectile Penetrating into Composite Concrete Targets.

From an offensive point of view, increasing the impact velocity of the projectile is an effective way to enlarge its penetration depth. However, as the projectile penetrates the target, there often exists an angle of attack, the resultant force on the projectile is in a different direction from that of projectile velocity, which causes the deflection of the projectile, and thus the strike effect is greatly weakened. From the other perspective, the deflection of the projectile can contribute to proactive protection of key targets from damage caused by a deeper penetration which has been an important consideration for actual protective structure. Presently, investigations on the deflection mechanism of the impact projectile are relatively few, and there is especially a lack of more comprehensive theoretical and experimental studies. In this paper, the mechanism of projectile deflection when penetrating a composite concrete target is thoroughly analyzed. The composite concrete target composed of a concrete fixed target and multiple diamond-shaped moving targets, similar to the structural system for multi-layer overlay extension, showed better anti-penetration performance in practical protective structures. The analytical model of projectile deflection during penetrating the target is established through simultaneously resolving the dynamic equations for the projectile and moving target. Penetration tests of the composite concrete target plate impacted by a 76 mm projectile were conducted to examine the effectiveness of the analytical model, where impact velocity and point and the size of the moving target were considered. On this basis, the influences of impact velocity and point on the deflection of the projectile are disclosed, and the effects of parameters of moving target are discussed. These findings can provide significant references for optimization of advanced protective structures and improvement of their anti-penetration performance.

Numerical Simulation Study on Factors Influencing Anti-Explosion Performance of Steel Structure Protective Doors under Chemical Explosion Conditions.

To study the mechanical deformation characteristics and anti-explosion mechanisms of steel-structure protective doors under chemical explosion shock wave loads, numerical simulations of loads and door damage were carried out using the AUTODYN and LS-DYNA software based on model tuning with actual field test results. The finite element simulation results were compared with the test results to verify the accuracy of the simulation model and material parameters. A parametric analysis was carried out on the influencing factors of the anti-explosion performance of the beam-plate steel structure protective door under typical shock wave loads. The impact of the material strength and geometry of each part of the protective door on its anti-explosion performance was studied. The results showed that the protective door sustained a uniform shock wave load and that increasing the steel strength of the skeleton could significantly reduce the maximum response displacement of the protective door. The steel strength increase of the inner and outer panels had little or a negligible effect on the anti-explosion performance of the protective door. The geometric dimensions of different parts of the protective door had different effects on the anti-explosion performance. Increasing the skeleton height had the most significant effect on the anti-explosion performance. The skeleton's I-steel flange thickness and the inner and outer panel thicknesses had less significant effects.

Preservation of Litchi Fruit with Nanosilver Composite Particles (Ag-NP) and Resistance against Peronophythora litchi.

Litchi (Litchi chinensis Sonn.) is susceptible to infection by Peronophythora litchi post storage, which rapidly decreases the sensory and nutritional quality of the fruit. In this study, the effects of nanosilver (Ag-NP) solution treatment on the shelf life of litchi fruit and the inhibition of P. litchi were examined, and the underlying mechanisms were discussed. For investigations, we used one variety of litchi ('Feizixiao'), dipping it in different concentrations of Ag-NP solution after harvesting. Meanwhile, we treated P. litchi with different concentrations of Ag-NP solution. According to the data analysis, litchi treated with 400 µg/mL Ag-NPs and stored at 4 °C had the highest health rate and the lowest browning index among all the samples. In the same trend, treatment with 400 µg/mL Ag-NPs produced the best results for anthocyanin content, total soluble solids content, and titratable acidity content. Additionally, according to the results of the inhibition test, 800 µg/mL Ag-NP solution had a 94.97% inhibition rate against P. litchi. Within 2-10 h following exposure to 400 µg/mL Ag-NP solution, the contents of superoxide dismutase, peroxidase, and catalase in P. litchi gradually increased and peaked, followed by a gradual decline. At this time, the integrity of the cell membrane of P. litchi could be broken by Ag-NP solution, and the sporangia showed deformed germ tubes and abnormal shapes. Taken together, these results suggested that Ag-NP treatment inhibited respiration and P. litchi activity, which might attenuate litchi pericarp browning and prolong the shelf life of litchi. Accordingly, Ag-NPs could be used as an effective antistaling agent in litchi fruit and as an ecofriendly fungicide for the post-harvest control of litchi downy blight. This study provides new insights into the application of Ag-NP as an antistaling agent for fruit storage and as an ecofriendly fungicide.