Gene SH3BGRL3 regulates acute myeloid leukemia progression through circRNA_0010984 based on competitive endogenous RNA mechanism.

Introduction: Acute myeloid leukemia (AML) is a malignant proliferative disease affecting the bone marrow hematopoietic system and has a poor long-term outcome. Exploring genes that affect the malignant proliferation of AML cells can facilitate the accurate diagnosis and treatment of AML. Studies have confirmed that circular RNA (circRNA) is positively correlated with its linear gene expression. Therefore, by exploring the effect of SH3BGRL3 on the malignant proliferation of leukemia, we further studied the role of circRNA produced by its exon cyclization in the occurrence and development of tumors. Methods: Genes with protein-coding function obtained from the TCGA database. we detected the expression of SH3BGRL3 and circRNA_0010984 by real-time quantitative polymerase chain reaction (qRT-PCR). We synthesized plasmid vectors and carried out cell experiments, including cell proliferation, cell cycle and cell differentiation by cell transfection. We also studied the transfection plasmid vector (PLVX-SHRNA2-PURO) combined with a drug (daunorubicin) to observe the therapeutic effect. The miR-375 binding site of circRNA_0010984 was queried using the circinteractome databases, and the relationship was validated by RNA immunoprecipitation and Dual-luciferase reporter assay. Finally, a protein-protein interaction network was constructed with a STRING database. GO and KEGG functional enrichment identified mRNA-related functions and signaling pathways regulated by miR-375. Results: We identified the related gene SH3BGRL3 in AML and explored the circRNA_0010984 produced by its cyclization. It has a certain effect on the disease progression. In addition, we verified the function of circRNA_0010984. We found that circSH3BGRL3 knockdown specifically inhibited the proliferation of AML cell lines and blocked the cell cycle. We then discussed the related molecular biological mechanisms. CircSH3BGRL3 acts as an endogenous sponge for miR-375 to isolate miR-375 and inhibits its activity, increases the expression of its target YAP1, and ultimately activates the Hippo signaling pathway involved in malignant tumor proliferation. Discussion: We found that SH3BGRL3 and circRNA_0010984 are important to AML. circRNA_0010984 was significantly up-regulated in AML and promoted cell proliferation by regulating miR-375 through molecular sponge action.

NDRG3 regulates imatinib resistance by promoting ß­catenin accumulation in the nucleus in chronic myelogenous leukemia.

Imatinib resistance in chronic myelogenous leukemia (CML) is a clinical problem. The present study examined the role of N­Myc downstream regulatory gene 3 (NDRG3) in imatinib resistance in CML. Quantitative PCR demonstrated that NDRG3 was highly expressed in patients with CML. Cell Counting Kit (CCK)­8 experiments proved that NDRG3 promoted the proliferation of K562 CML cells and enhanced imatinib resistance. Dual­luciferase assay showed that microRNA (miR)­204­5p inhibited expression of NDRG3 and immunofluorescence experiments showed that NDRG3 promoted accumulation of ß­catenin in the nucleus, thereby increasing the expression of downstream drug resistance­ and cell cycle­associated factors (c­Myc and MDR1). At the same time, cell proliferation experiments showed that ß­catenin played a role in cell proliferation and drug resistance. Co­transfection with small interfering (si)­ß­catenin partially reversed the effect of NDRG3. This finding indicated that NDRG3 plays an important role in imatinib resistance and miR­204­5p and ß­catenin are involved in the biological behavior of NDRG3. The present results provide theoretical support for overcoming drug resistance in CML.

A Novel Aging-Related Prognostic lncRNA Signature Correlated with Immune Cell Infiltration and Response to Immunotherapy in Breast Cancer.

Breast cancer (BC) is among the most universal malignant tumors in women worldwide. Aging is a complex phenomenon, caused by a variety of factors, that plays a significant role in tumor development. Consequently, it is crucial to screen for prognostic aging-related long non-coding RNAs (lncRNAs) in BC. The BC samples from the breast-invasive carcinoma cohort were downloaded from The Cancer Genome Atlas (TCGA) database. The differential expression of aging-related lncRNAs (DEarlncRNAs) was screened by Pearson correlation analysis. Univariate Cox regression, LASSO-Cox analysis, and multivariate Cox analysis were performed to construct an aging-related lncRNA signature. The signature was validated in the GSE20685 dataset from the Gene Expression Omnibus (GEO) database. Subsequently, a nomogram was constructed to predict survival in BC patients. The accuracy of prediction performance was assessed through the time-dependent receiver operating characteristic (ROC) curves, Kaplan-Meier analysis, principal component analyses, decision curve analysis, calibration curve, and concordance index. Finally, differences in tumor mutational burden, tumor-infiltrating immune cells, and patients' response to chemotherapy and immunotherapy between the high- and low-risk score groups were explored. Analysis of the TCGA cohort revealed a six aging-related lncRNA signature consisting of MCF2L-AS1, USP30-AS1, OTUD6B-AS1, MAPT-AS1, PRR34-AS1, and DLGAP1-AS1. The time-dependent ROC curve proved the optimal predictability for prognosis in BC patients with areas under curves (AUCs) of 0.753, 0.772, and 0.722 in 1, 3, and 5 years, respectively. Patients in the low-risk group had better overall survival and significantly lower total tumor mutational burden. Meanwhile, the high-risk group had a lower proportion of tumor-killing immune cells. The low-risk group could benefit more from immunotherapy and some chemotherapeutics than the high-risk group. The aging-related lncRNA signature can provide new perspectives and methods for early BC diagnosis and therapeutic targets, especially tumor immunotherapy.

[Size Distribution and Source Appointment of Road Particles During Winter in Tianjin].

The significant role of traffic emissions mixed from various sources in urban air pollution has been widely recognized. However, the corresponding contributions to the roadside particle distribution are poorly understood due to the mixed impacts of various sources. Particle number concentrations of different sizes at the roadside in Nankai District of Tianjin were continuously monitored using a portable aerosol particle spectrometer during the morning rush hour (07:30-09:20) from Nov. 9, 2018 to Jan. 6, 2019. Characteristic and influencing factors of particle size distributions were discussed combined with temperature and relative humidity data, while potential sources of particles at the roadside were identified based on size distribution analysis. The results showed that the average total particle number concentrations were 502 cm-3, and the concentrations of the accumulation mode and coarse mode were 500 cm-3 and 2 cm-3, respectively. The distribution of number concentrations at the roadside was unimodal and primarily concentrated at 0.25-0.50 µm, with peak sizes at 0.28-0.30 µm. The same distribution trend of particle number concentration and difference in the concentration in the same segment size were observed at different periods. Vehicle activity level was the main influencing factor of road particulate matter concentration on different weekdays; the probability of the high value of road particulate matter concentration was reduced by a reasonable combination of the vehicle tail numbers. Temperature and relative humidity were both found to be positively correlated with the number concentration of particles. With the increase in temperature and relative humidity, the total and peak particle number concentration showed an overall upward trend. In addition, the peak particle size increased from 0.28-0.30 µm to 0.35-0.40 µm when relative humidity was higher than 80%. Three sources, including road dust, brake and tire wear, and the aging particles from vehicle exhaust, were identified using positive matrix factorization in this study. Road dust contributed 8.6% of the total number concentration, which mainly consisted of particles with sizes above 5.00 µm. Brake and tire wear contributed 2.8% of the total number concentration of particles with a size range of 0.80-4.00 µm. The aging particles from vehicle exhaust contributed the most (88.5%), with a peak at 0.25-0.65 µm. The sources of roadside particles were mainly related to vehicle activity, whereas temperature and relative humidity also affected the particle number size distribution.

Characteristics of PM2.5 in an Industrial City of Northern China: Mass Concentrations, Chemical Composition, Source Apportionment, and Health Risk Assessment.

Urban and suburban PM2.5 samples were collected simultaneously during selected periods representing each season in 2019 in Zibo, China. Samples were analysed for water-soluble inorganic ions, carbon components, and elements. A chemical mass balance model and health risk assessment model were used to investigate the source contributions to PM2.5 and the human health risks posed by various pollution sources via the inhalation pathway. Almost 50% of the PM2.5 samples exceeded the secondary standard of China's air quality concentration limit (75 µg/m3, 24 h). Water-soluble inorganic ions were the main component of PM2.5 in Zibo, accounting for 50 ± 8% and 56 ± 11% of PM2.5 at the urban and suburban sites, respectively. OC and OC/EC decreased significantly in the past few years due to enhanced energy restructuring. Pearson correlation analysis showed that traffic emissions were the main source of heavy metals. The Cr(VI) concentrations were 1.53 and 1.92 ng/m3 for urban and suburban sites, respectively, exceeding the national ambient air quality standards limit of 0.025 ng/m3. Secondary inorganic aerosols, traffic emissions, and secondary organic aerosols were the dominant contributors to PM2.5 in Zibo, with the total contributions from these three sources accounting for approximately 80% of PM2.5 and the remaining 20% attributed to traffic emissions. The non-carcinogenic risks from crustal dust for children were 2.23 and 1.15 in urban and suburban areas, respectively, exceeding the safe limit of 1.0 in both locations, as was the case for adults in urban areas. Meanwhile, the carcinogenic risks were all below the safe limit, with the non-carcinogenic and carcinogenic risks from traffic emissions being just below the limits. Strict control of precursor emissions, such as SO2, NOx, and VOCs, is a good way to reduce PM2.5 pollution resulting from secondary aerosols. Traffic control, limiting or preventing outdoor activities, and wearing masks during haze episodes may be also helpful in reducing PM2.5 pollution and its non-carcinogenic and carcinogenic health impacts in Zibo.

Aircraft-based observation of gaseous pollutants in the lower troposphere over the Beijing-Tianjin-Hebei region.

To investigate the spatial and vertical distribution of atmospheric pollutants (SO2, NOx, CO and O3), aircraft-based measurements (model: Yun-12, 12 flights, 27 h total flight time) were conducted from near the surface up to 2400 m over the Beijing-Tianjin-Hebei (BTH) region between June 17th and July 22nd 2016. The results showed that high concentrations of primary gaseous pollutants (SO2, NOx, CO) were generally present in Beijing, Tianjin, Langfang and Tangshan areas, while high values of O3 frequently appeared in areas far from the city. The flights at noon and dusk measured higher O3 concentrations at 600 m and lower O3 concentrations at higher altitudes, implying a strong influence by photochemical production. Back trajectory analysis suggested that the high levels of gaseous pollutants, especially at 600 m, were associated with pollution sources transported from the southerly direction during the observation period. The first simultaneous vertical distribution measurements using aircraft and tethered balloon were conducted in Gaocun (a rural site between Beijing and Tianjin) on June 17th. The results indicated that an inversion layer at the top of the planetary boundary layer (PBL) significantly suppressed vertical exchange through the PBL and resulted in a "two-layer" vertical distribution of pollutants above and below the PBL. Additionally, a residual high O3 layer (79.9 ± 2.5 ppb, 500-1000 m) was observed above the PBL, and it contributed to the surface peak O3 level at noon through downward transport along with the opening up of the PBL. These results indicate that coupled effects of horizontal and vertical transport should be investigated in future studies to improve the chemical transport models used to study the vertical distribution and regional transport over the BTH region.

[Distribution Characteristics and Source Apportionment of Elements Bonded with PM2.5 and PM10 in Linyi].

To investigate the pollution characteristics and sources of elements bonded with PM2.5 and PM10 in Linyi, PM2.5 and PM10 sample collections were carried out simultaneously in Linyi from December 2016 to October 2017, and 23 elements were determined by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES), with the enrichment factor method and PMF employed to determine the source apportionment. The results indicated that the dominant elements in PM2.5 and PM10 were recognized as Si, Ca, Al, Fe, K, Na, and Mg, accounting for 92.93% and 94.61% of the total measured elements, respectively. The concentrations of 18 elements (excluding Ti, Ni, Mo, Cd, and Mg) were highest in winter and spring, and lowest in summer and autumn. Si, Al, Ca, K, and Na showed the highest levels in spring, mainly distributed in coarse particles; Cu, Zn, Pb, and Sb showed the highest levels in winter, mainly distributed in fine particles. The enrichment factor results showed that the enrichment of Cd, Sb, and Bi was significant, mainly originated by anthropogenic sources such as coal combustion, industrial production, and waste incineration. Based on the analysis results of PMF, coal, and copper smelting, municipal waste incineration, fugitive dust, vehicle emissions, and industrial sources were the main sources of elements in PM2.5, accounting for 22.64%, 7.49%, 41.22%, 14.71%, and 13.94%, respectively. For PM10, fugitive dust, coal and copper smelting, vehicle emissions, and industrial sources were the main sources of elements, contributing 55.47%, 19.80%, 7.48%, and 12.83%, respectively. Our results suggested that the main contributors to particulate matter pollution in Linyi during the sampling period were fugitive dust, and coal and copper smelting.

Vertical distribution of volatile organic compounds conducted by tethered balloon in the Beijing-Tianjin-Hebei region of China.

Volatile organic compounds (VOCs) as precursors of ozone and secondary organic aerosols can cause adverse effects on the environment and human health. However, knowledge of the VOC vertical profile in the lower troposphere of major Chinese cities is poorly understood. In this study, tethered balloon flights were conducted over the juncture of Beijing-Tianjin-Hebei in China during the winter of 2016. Thirty-six vertical air samples were collected on selected heavy and light pollution days at altitudes of 50-1000 meters above ground level. On average, the concentration of total VOCs (TVOCs) at 50-100 m was 4.9 times higher than at 900-1000 m (46.9 ppbV vs. 8.0 ppbV). TVOC concentrations changed rapidly from altitudes of 50-100 to 401-500 m, with an average decrease of 72%. With further altitude increase, the TVOC concentration gradually decreased. The xylene/benzene ratios of 34/36 air samples were lower than 1.1, and the benzene/toluene ratios of 34/36 samples were higher than 0.4, indicating the occurrence of aged air mass during the sampling period. Alkenes contributed most in terms of both OH loss rate (39%-71%) and ozone formation potential (40%-72%), followed by aromatics (6%-38%). Finally, the main factors affecting the vertical distributions of VOCs were local source emission and negative dispersion conditions on polluted days. These data could advance our scientific understanding of VOC vertical distribution.

Chemical characteristics of road dust PM2.5 fraction in oasis cities at the margin of Tarim Basin.

In order to understand the compositions characteristics of particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) fraction in road dust (RD2.5) of oasis cities on the edge of Tarim Basin, 30 road dust (RD) samples were collected in Kashi, Cele, and Yutian in the spring, 2018, and RD2.5 was collected using the resuspension approach. Eight water-soluble ions, 39 trace elements and 8 fractions of carbon-containing species in PM2.5 were analyzed. Ca2+ and Ca were the most abundant ions and elements in RD2.5 (7.1% and 9.5%). Cl- in RD2.5 was affected not only by attributed to saline-alkali soils in oasis cities of the Tarim Basin and dust from Taklimakan Desert but also by human activities. Moreover, the organic carbon/elemental carbon (OC/EC) ratio indicated that carbon components in RD2.5 in Cele town mainly come from fossil fuel combustion, while those in Yutian and Kashi mainly come from biomass combustion. It is noteworthy that high Ca in RD2.5 was seriously affected by anthropogenic emissions, and high Na and K contents in RD2.5 could be derived from soil and desert dust. It was estimated that Cd, Tl, Sn and Cr were emitted from anthropogenic emissions using the enrichment factor. The coefficients of divergence (COD) result indicated that the influence of local emission on road dust emission is greater than that of long-distance transmission. This study is the first time to comprehensively analyze the chemical characteristics of road dust in oasis cities, and the results provides the sources of road dust at the margin of Tarim Basin.

Chemical Characteristics of Atmospheric PM10 and PM2.5 at a Rural Site of Lijiang City, China.

Emissions from biomass burning are very serious in Southeast Asia and South Asia in April. In order to explore the effect of long-range transport of biomass emissions from the Indochina Peninsula in Southwest China during the period of the southeast monsoon season and to find out the main pollution sources in local atmospheric PM2.5, a field campaign was conducted from 6-26 April 2011 in Lijiang, China. Twenty-four-hour PM10 and PM2.5 filter samples were collected, and inorganic ions, elements, and carbonaceous components (including organic carbon (OC) and elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs)) were measured. The monthly mean mass concentrations of particulate matter (PM) were 40.4 and 14.4 µg/m3 for PM10 and PM2.5, respectively. The monthly mean concentrations of OC and EC in PM10 were 6.2 and 1.6 µg/m3, respectively. The weekly mean concentrations of ∑PAHs and ∑NPAHs were 11.9 ng/m3 and 289 pg/m3, respectively, in atmospheric PM10 of Lijiang. The diagnostic ratios of PAH and NPAH isomers were used to analyze the sources of PAHs and NPAHs in PM10. The ratios of Benz(a)anthracene/(Chrysene+Benz(a)anthracen), Fluoranthene/(Fluoranthene+Pyrene) and Indeno(1,2,3-cd)pyrene/(Benzo(g,h,i)perylene+Indeno(1,2,3-cd)pyrene) were 0.45 ± 0.04, 0.61 ± 0.01, and 0.53 ± 0.03, respectively, indicating the contribution from coal combustion and biomass burning. The 1-nitropyrene/Pyrene (1-NP/Pyr) ratio was 0.004 ± 0.001, suggesting that the contribution to NPAHs mainly came from coal combustion. Sulfate was the most prominent inorganic ionic species, with monthly mean levels of 2.28 and 1.39 µg/m3 in PM10 and PM2.5, respectively. The monthly mean mass ratios of NO3-/SO42- were 0.40 and 0.23 in PM10 and PM2.5, respectively, indicating that the contribution of atmospheric anions from coal combustion sources was much more important than that from other sources. Based on the relatively high SO42- concentrations and low NO3-/SO42- ratios, combined with the data analysis of isomer ratios of PAHs and NPAHs, we can conclude that coal combustion, traffic, and dust were the major contributors to local atmospheric PM in Lijiang city, while biomass burning may also have contributed to local atmospheric PM in Lijiang city to some degree.

[Characterization of PM10 and PM2.5 Source Profiles for Emissions from Nonmetal Mineral Products Manufacturing Processes].

In view of the insufficient source profiles for emissions from nonmetal mineral products manufacturing processes in China, a dilution sampling system was used to collect PM10 and PM2.5 samples from glassmaking, ceramics, and firebrick manufacturing sources between February and June of 2017. The characteristics of 50 chemical components in the samples were studied to identify source profiles. The results showed that the dominant composition of particulate matter in glassmaking plant profiles was Na, with percentages ranging from 9.2% to 18.5%. Ceramics profiles were enriched in Al, Si, Ca, and Fe, with percentages ranging from 1.7% to 8.7%. Refractory brick and shale manufacturing process profiles were characterized by high abundances of SO42- (36.9%-48.1%) and NH4+ (7.7%-17.0%). Chemical components in the source profiles varied with the different fuel types and desulfurization, denitrification, and dedusting methods. The coefficients of divergence (CD) between PM2.5 and PM10 from the same process were similar except for the results from the shale manufacturing process (CD values>0.3), thus indicating that the elements profiles of PM2.5 might be similar to those in PM10. Profiles of the same particle size from different processes were significantly different from one another, with CD values ranging from 0.42 to 0.76. The CD values for float glass and medicinal glass, and the CD values for the two ceramic enterprises were relatively small. The distributions of weighted differences (R/U ratios) were used to compare the differences of components between the source profiles, and results showed that the identified components for glass manufacturing, ceramic manufacturing, fireproof bricks, and page rock bricks were Na and As, Al and Ti, NO3- and NH4+, and SO42- and NH4+, respectively.

[Emission Characteristics of Exhaust PM and Its Carbonaceous Components from China â ¢ to China â £ Diesel Vehicles in Shenyang].

Diesel vehicles were the primary source of atmospheric particulate matter (PM) emitted by motor vehicles. To study the emission factors and carbon components of PM2.5 and PM10 from diesel vehicles in Shenyang, exhaust PM samples were collected from 15 diesel vehicles including small, medium, and large passenger vehicles, and light, medium, and heavy-duty trucks under China Ⅲ and China Ⅳ emission standards. This was undertaken using a dilution channel sampling system, and the carbon components were also analyzed. The results showed that the average distance-based PM2.5 and PM10 emission factors for diesel vehicles under China Ⅲ were (0.193±0.092) g·km-1 and (0.338±0.305) g·km-1, respectively, and for China Ⅳ were (0.085±0.038) g·km-1 and (0.100±0.042) g·km-1, respectively. This shows that the PM emission factors decreased significantly with the improvement of emission standards. Under the same emission standards, emission factors increased with the increase of vehicle passenger volume or cargo capacity. TC (total carbon) was the main component of the emissions from diesel vehicles. The mass fraction of TC under China Ⅳ (23%-48%) was significantly lower than under China Ⅲ (29%-70%). The mass fraction of elemental carbon (EC) for all types of diesel vehicles was greater than organic carbon (OC). The OC/EC value was 0.70±0.29, and the OC/EC value for diesel vehicles under China Ⅳ was lower than under China Ⅲ. The total mileage of passenger vehicles was significantly higher than that of trucks, resulting in higher fuel consumption. The mass fraction of OC and EC in passenger vehicles was higher than for trucks under the same emission standards. EC2 (elemental carbon which was measured at temperatures of 700℃) was the highest carbon content of diesel vehicles under China Ⅲ and China Ⅳ emission standards, which can be used in the identification of diesel vehicles in source apportionment studies.

A seriously sand storm mixed air-polluted area in the margin of Tarim Basin: Temporal-spatial distribution and potential sources.

In order to analyze the temporal-spatial distribution characteristics of PM2.5, PM10, SO2, NO2, CO and O3 in five cities and the potential sources of PM10 in southern Xinjiang during 2016, we collected one year officially released data for analysis. The average PM10, PM2.5, SO2, NO2, O3 and CO concentrations were 289 ±â€¯363, 99 ±â€¯106, 17 ±â€¯9, 29 ±â€¯11, 65 ±â€¯25 µg m-3 and 1.3 ±â€¯0.6 mg m-3 in southern Xinjiang in 2016, respectively. The air pollutants presented distinct seasonal and spatial distribution characteristics. During sandstorm process, the particulate matters (PM) concentrations increased abruptly, with the PM10 and PM2.5 maximum concentrations exceeding 1000 and 500 µg m-3 in each city. The backward trajectory results showed that the air masses in Akesu, Kurla, Hotan, Kashi and Atushi were mainly from the Bayingol Mongolian Autonomous Prefecture, Kyrgyzstan, Kizilesu Kirgiz Autonomous Prefecture and Taklimakan Desert (TD). In addition, TD was the main potential contributor to ambient PM10 in five cities during the dust season (DS), with a weighted potential source contribution function (WPSCF) > 0.9. While the trajectories of air masses from TD, Bayingol Mongolian Autonomous Prefecture, Urumqi-Changji Area and local emission were potential sources contributing to PM2.5 in these five cities during DS, with a WPSCF > 0.7. Moreover, the high weighted concentration weighted trajectory (WCWT) values were distributed in the Tarim basin, with PM10 > 700 µg m-3, however, the local emission and long distance transport contributed to the PM2.5 > 160 µg m-3 for five cities. This study comprehensively analyzes the pollution characteristics of air pollutants in five important cities in the southern margin of the Tarim Basin for the first time, and will provide an important reference basis for the prevention and control of air pollution in southern Xinjiang.

Emission factors of polycyclic aromatic hydrocarbons from domestic coal combustion in China.

Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons (PAHs) are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4-ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.

[Effect of astragalus injection on U937 leukemia cells proliferation and apoptosis and relevant molecular mechanisms].

OBJECTIVE: To study the effect of astragalus injection on U937 leukemia cells proliferation and apoptosis and relevant molecular mechanisms. METHODS: Leukemia cell line U937 cells were treated with different concentrations of astragalus (62.5, 125, 250, 500, 1 000 µg/mL). The U937 cells without astragalus treatment were used as the control group. The ability of cell proliferation was measured by MTT method. Flow cytometry was used to explore cell apoptosis. The cell morphology changes were observed under a fluorescent microscope by dyeing Hoechst33258. mRNA expression of c-myc and p27 in U937 cells which was exposed in 1 000 µg/mL astragalus after 0, 12, 24 and 48 hours was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Various concentrations of astragalus injection inhibited U937 cell proliferation effectively compared with the control group (P<0.05). They also induced U937 cells apoptosis and the apoptosis rate reached to (63 ± 4)% in the 1 000 µg/mL astragalus treatment group. mRNA expression level of c-myc was gradually declined and p27 mRNA expression was gradually increased with astragalus treatment time (P<0.01). CONCLUSIONS: Astragalus injection may inhibit proliferation and induce apoptosis of leukemia cell line U937 in vitro. This contributes to down-regulation of c-myc expression and up-regulation of p27 expression.

Theoretical study on the reaction mechanism of ozone addition to the double bonds of keto-limonene.

The reaction mechanism of ozone (O3) addition to the double bonds of gas phase keto-limonene was investigated using ab initio methods. Two different possibilities for O3 addition to the double bond were considered and two corresponding van der Waals complexes (Complex 1 and Complex 2) were found for 1-endo and 2-endo. The rate constants were calculated using the transition state theory at the CCSD(T)/6-31G(d) + CF//B3LYP/6-31G(d,p) level. The high-pressure limit of the total rate constant at 298 K was 3.51 x 10(-16) cm3/(molecule x sec), which was in a good agreement with the experimental data.