Limonene anti-TMV activity and its mode of action.

The main component of orange peel essential oil is limonene. Limonene is a natural active monoterpene with multiple functions, such as antibacterial, antiseptic and antitumor activity, and has important development value in agriculture. This study found that limonene exhibited excellent anti-tobacco mosaic virus (TMV) bioactivity, with results showing that its protection activity, inactivation activity, and curative activity at 800 µg/mL were 84.93%, 59.28%, and 58.89%, respectively-significantly higher than those of chito-oligosaccharides. A direct effect of limonene on TMV particles was not observed, but limonene triggered the hypersensitive response (HR) in tobacco. Further determination of the induction activity of limonene against TMV demonstrated that it displayed good induction activity at 800 µg/mL, with a value of 60.59%. The results of physiological and biochemical experiments showed that at different treatment days, 800 µg/mL limonene induced the enhancement of defense enzymes activity in tobacco, including of SOD, CAT, POD, and PAL, which respectively increased by 3.2, 4.67, 4.12, and 2.33 times compared with the control (POD and SOD activities reached highest on the seventh day, and PAL and CAT activities reached highest on the fifth day). Limonene also enhanced the relative expression levels of pathogenesis related (PR) genes, including NPR1, PR1, and PR5, which were upregulated 3.84-fold, 1.86-fold and 1.71-fold, respectively. Limonene induced the accumulation of salicylic acid (SA), and increased the relative expression levels of genes related to SA biosynthesis (PAL) and reactive oxygen species (ROS) burst (RBOHB), which respectively increased by 2.76 times and 4.23 times higher than the control. Systemic acquired resistance (SAR) is an important plant immune defense against pathogen infection. The observed accumulation of SA, the enhancement of defense enzymes activity and the high-level expression of defense-related genes suggested that limonene may induce resistance to TMV in tobacco by activating SAR mediated by the SA signaling pathway. Furthermore, the experimental results demonstrated that the expression level of the chlorophyll biosynthesis gene POR1 was increased 1.72-fold compared to the control in tobacco treated with 800 µg/mL limonene, indicating that limonene treatment may increase chlorophyll content in tobacco. The results of pot experiment showed that 800 µg/mL limonene induced plant resistance against Sclerotinia sclerotiorum (33.33%), Phytophthora capsici (54.55%), Botrytis cinerea (50.00%). The bioassay results indicated that limonene provided broad-spectrum and long-lasting resistance to pathogen infection. Therefore, limonene has good development and utilization value, and is expected to be developed into a new botanical-derived anti-virus agent and plant immunity activator in addition to insecticides and fungicides.

Ursolic acid induces apoptosis and autophagy in oral cancer cells.

Oral squamous cell carcinoma (OSCC) is the fifth common cause of cancer mortality in Taiwan with high incidence and recurrence and needs new therapeutic strategies. In this study, ursolic acid (UA), a triterpenoid, was examined the antitumor potency in OSCC cells. Our results showed that UA inhibited the proliferation of OSCC cells in a dose- and time-dependent manner in both Ca922 and SCC2095 oral cancer cells. UA induced caspase-dependent apoptosis accompanied with the modulation of various biological biomarkers including downregulating Akt/mTOR/NF-κB signaling, ERK, and p38. In addition, UA inhibited angiogenesis as evidenced by abrogation of migration/invasion and blocking MMP-2 secretion in Ca922 cells. Interestingly, UA induced autophagy in OSCC cells, as manifested by LC3B-II conversion and increased p62 expression and accumulation of autophagosomes. Inhibition by autophagy inhibitor enhanced UA-mediated apoptosis in Ca922 cells. The experiment provides a rationale for using triterpenoid in the treatment of OSCC.

The role of professional commitment in improving nurses' professional capabilities and reducing their intention to leave: Two-wave surveys.

BACKGROUND: Social cognitive career theory (SCCT) can explain the mechanism underlying the formulation of nurse turnover intention. However, little is known about the role of professional commitment in such a mechanism. AIMS: The aim of this study was to explore how elements of SCCT have an impact on the three aspects of professional commitment and thus nurses' intention to leave the profession. DESIGN: This study used surveys to collect two-wave data. METHODS: The participants were sampled in all available units of a major medical centre in 2017. By using proportionate random sampling methods, we successfully followed up a representative sample of 524 full-time nurses. Most participants (98.1%) were female. Items came from Cunningham et al.'s Self-Efficacy Scale, Outcome Expectations Scale, Human Capital Scale and Vocational Interest Scale; Meyer et al.'s Professional Commitment Scale; and Teng et al.'s Turnover Intention Scale. Structural equation modelling was used to test the hypotheses. RESULTS: Self-efficacy was positively related to outcome expectation. Outcome expectation was positively related to career interest. Career interest was positively related to affective professional commitment. Human capital was positively related to normative professional commitment. Affective professional commitment was positively related to intention to improve professional capabilities, which was further negatively related to intention to leave the profession. CONCLUSION: Aspects of professional commitment are important process variables in the impact of self-efficacy and outcome expectation on nurses' turnover intention.

PM2.5 source apportionment identified with total and soluble elements in positive matrix factorization.

Source apportionments of urban aerosols identified with positive matrix factorization (PMF) are sensitive to input variables. So far, total elements were frequently included as effective factors in PMF-based source apportionment. We investigated the advances to involve soluble parts of elements in the source apportionment with four data sets of PM2.5 composition observed at a coastal city (Qingdao) in northern China: water-soluble ions plus organic and elemental carbon (IC set), the IC set plus total elements (ICTE set), the IC set plus soluble elements (ICSE set), and the IC set plus both total elements and soluble elements (ICAE set). The apportionments of six sources, including secondary sulfate, secondary nitrate, secondary oxalate, sea salt, biomass burning and dust, were identified with the IC set. In comparison, pollutants from vehicle + coal combustion, ship emissions, waste incineration and industrial activities were also identified with the ICTE, ICSE, or ICAE sets. We found that the PMF solutions of the ICAE set could distinguish aged and fresh dust, and identify fly ash and aged pollutants from industrial sources. The profiles and corresponding time series of vehicle + coal combustion, secondary aerosols, ship emissions, sea salt, and biomass burning emissions identified with the four data sets were very similar, while discrepancies were encountered for waste incineration, dust, and industrial sources. These results indicate the benefits and potentials with total and soluble elements involved in PMF-based source apportionments.

Investigation of a haze-to-dust and dust swing process at a coastal city in northern China part I: Chemical composition and contributions of anthropogenic and natural sources.

The long retention of dust air masses in polluted areas, especially in winter, may efficiently change the physicochemical properties of aerosols, causing additional health and ecological effects. A large-scale haze-to-dust weather event occurred in the North China Plain (NCP) region during the autumn-to-winter transition period in 2018, affecting the coastal city Qingdao several times between Nov. 27th and Dec. 1st. To study the evolution of the pollution process, we analyzed the chemical characteristics of PM2.5 and PM10-2.5 and source apportionments of PM2.5 and PM10, The dust stagnated around NCP and moved out and back to the site, noted as dust swing process, promoting SO42- formation in PM2.5 and NO3- formation in PM10-2.5. Source apportionments were analyzed using the Positive Matrix Factorization (PMF) receptor model and weighted potential source contribution function (WPSCF). Before the dust invasion, Qingdao was influenced by severe haze; waste incineration and coal burning were the major contributors (~80 %) to PM2.5, and the source region was in the southwest of Shandong Province. During the initial dust event, mineral dust and the mixed factor of dust and sea salt were the major contributors (46.0 % of PM2.5 and 86.5 % of PM10). During the polluted dust period, the contributions of regional transported biomass burning (22.3 %), vehicle emissions (20.8 %), and secondary aerosols (33.8 %) to PM2.5 from the Beijing-Tianjin-Hebei region significantly increased. The secondary aerosols source was more regional than that of vehicle emissions and biomass burning and contributed considerably to PM10 (30.8 %) during the dust swing process. Our findings demonstrate that environmental managers should consider the possible adverse effects of winter dust on regional and local pollution.

[Clinical study on repairing subtotal perforation of tympanic membrane with cartilage island technique combined with palisade technique under otoscope].

Objective:To investigate the healing rate of subtotal perforation of tympanic membrane repaired by cartilage island technique combined with palisade cartilage technique under otoscope. Methods:A retrospective analysis was performed on 189 patients with chronic suppurative otitis media who were admitted to the Department of Otolaryngology and Head and Neck Surgery of Hunan Provincial People's Hospital from January 2018 to January 2020. The patients were divided into twogroups, in group onethere were 100 patients treated by senior surgeon, which were divided into two subgroups, Group A （68 cases） were treated with cartilage island technique alone, and Group B （32 cases） were treated with cartilage island technique combined with palisade cartilage technique. In group two there were 89 patients treated by junior surgeons, which were divided into two subgroups. In group C, 50 cases were treated with cartilage island technique alone, and in group D, 39 cases were treated with cartilage island technique combined with palisade cartilage technique. Results:The healing rate of tympanic membrane in group 1 was 96.0% （96/100）, and in group 2 was 87.6%（78/89）.There was statistically significant in group 1 and group 2（χ²=4.504, P=0.034）.The healing rate of tympanic membrane was 94.1% （64/68） in group A, 100%（32/32）in group B, 80.0%（40/50） in group C, and 97.4% （38/39） in group D. There was no statistically significant difference between group A and group B （χ²=1.961, P=0.161）, there was statistically significant difference between group C and group D （χ²=6.149, P=0.013）, and there was statistically significant difference between group A and group C（χ²=5.492, P=0.019）There was no statistical difference between group B and group D（χ²=0.832, P=0.362）. Conclusion:For beginners of tympanoplasty, the use of cartilage island technique combined with palisade cartilage technique in otoscope can significantly improve the success rate of tympanoplasty with subtotal tympanic perforation.