[Research on alien invasive plants in Jingzhou County, Hunan Province, China]. / æ¹–å—çœé–å·žåŽ¿å¤–æ¥å ¥ä¾µæ¤ç‰©ç ”ç©¶.

Harm from alien invasive plants is increasing in Jingzhou County, Hunan Province. Based on a one-year field investigation and available literature, we investigated species composition, origin, flora, degree of harm and distribution pattern of invasive plants in the county. The results showed that there were 34 invasive plant species from 27 genera and 16 families in this County. The dominant invasive species belonged to Asteraceae (8 species) and Amaranthaceae (6 species), which accounted for 23.5% and 17.7%, respectively. The majority of invasive plants originated from South America (45.7%) and North America (30.4%). Tropical flora showed a significantly higher representation than temperate flora, signifying robust tropical characteristics amongst the invasive plant population. Based on hazard level classification, we recognized four types as malicious invasion (Level 1): Alternanthera philoxeroides, Erigeron annuus, E. canadensis, and Xanthium chinense. In addition, five types were classified as severe invasion (Level 2), eight types as local invasion (Level 3), fifteen types as general invasion (Level 4), while two types were still under observation (Level 5). The pattern of distribution demonstrated that invasive plants in Jingzhou County mostly spread along the verges of transportation roads, in human settlements, and in a few areas of water flow. The higher levels of invasion damage were principally concentrated in the central part of Jingzhou County.

Lesion human leukocyte antigen-E is associated with favourable prognosis for patients with oesophageal squamous cell carcinoma.

OBJECTIVE: To investigate the clinical significance of human leukocyte antigen (HLA)-E levels in oesophageal squamous cell carcinoma (ESCC). METHODS: The levels of HLA-E immunostaining in ESCC lesions and 47 corresponding adjacent normal tissues were measured using immunohistochemistry. The correlation between the levels of immunostaining and clinical parameters was analysed. RESULTS: This study analysed 110 paraffin-embedded primary tumour lesions and 47 case-controlled paracancerous tissues that were surgically resected from 110 patients with ESCC. Positive immunostaining for HLA-E was observed in 88.2% (97 of 110) of ESCC lesions and 29.8% (14 of 47) of normal oesophageal tissues. There was no correlation between HLA-E immunostaining in ESCC lesions and clinicopathological characteristics such as lymph node metastasis, tumour-node-metastasis stage and differentiation grade. Kaplan-Meier survival analysis revealed a significantly better prognosis in patients with higher levels of HLA-E immunostaining than in those with lower levels of HLA-E immunostaining; overall survival was 28.6 months (95% confidence interval [CI], 23.2, 34.0) versus 15.3 months (95% CI, 11.5, 19.1), respectively. Furthermore, multivariate analysis showed that the HLA-E level was an independent prognostic factor in patients with ESCC. CONCLUSION: A higher level of HLA-E immunostaining was associated with favourable survival in patients with ESCC.

Rpb3 promotes hepatocellular carcinoma through its N-terminus.

The expression of RNA polymerase II subunit 3 (Rpb3) was found frequent up-regulation in Hepatocellular carcinoma (HCC) tumors. Significant associations could also be drawn between increased expressions of Rpb3 and advance HCC staging and shorter disease-free survival of patients. Overexpression of Rpb3 increased HCC cell proliferation, migratory rate and tumor growth in nude mice, whereas suppression of Rpb3 using shRNA inhibited these effects. For mechanism study, we found that Rpb3 bound directly to Snail, downregulated E-cadherin, induced HCC cells epithelial-mesenchymal transition (EMT). In particular, N-terminus of Rpb3 blocked Rpb3 binding to Snail, inhibited Rpb3-high-expression HCC cells proliferation, migration, tumor growth in nude mice, and also inhibited DEN-induced liver tumorigenesis. Furthermore, N-terminus of Rpb3 did not inhibit normal liver cells or Rpb3-low-expression HCC cells proliferation. These findings suggest that N-terminus of Rpb3 selectively inhibits Rpb3-high-expression HCC cells proliferation. N-terminus of Rpb3 may be useful in treating patients diagnosed with Rpb3-high-expression HCC.

[Studies of ozone formation potentials for benzene and ethylbenzene using a smog chamber and model simulation].

Ozone formation potentials from irradiations of benzene-NO(x) and ethylbenzene-NO(x) systems under the conditions of different VOC/NO(x) ratios and RH were investigated using a characterized chamber and model simulation. The repeatability of the smog chamber experiment shows that for two sets of ethylbenzene-NO(x) irradiations with similar initial concentrations and reaction conditions, such as temperature, relative humidity and relative light intensity, the largest difference in O3 between two experiments is only 4% during the whole experimental run. On the basis of smog chamber experiments, ozone formation of photo-oxidation of benzene and ethylbenzene was simulated in terms of the master chemical mechanism (MCM). The peak ozone values for benzene and ethylbenzene simulated by MCM are higher than the chamber data, and the difference between the MCM-simulated results and chamber data increases with increasing RH. Under the conditions of sunlight irradiations, with benzene and ethylbenzene concentrations being in the range of (10-50) x 10(-9) and NO(x) concentrations in the range of (10-100) x 10(-9), the 6 h ozone contributions of benzene and ethylbenzene were obtained to be (3.1-33) x 10(-9) and (2.6-122) x 10(-9), whereas the peak O3 contributions of benzene and ethylbenzene were (3.5-54) x 10(-9) and (3.8-164) x 10(-9), respectively. The MCM-simulated maximum incremental reactivity (MIR) values for benzene and ethylbenzene were 0.25/C and 0.97/C (per carbon), respectively. The maximum ozone reactivity (MOR) values for these two species were obtained to be 0.73/C and 1.03/C, respectively. The MOR value of benzene from MCM is much higher than that obtained by carter from SAPRC, indicating that SAPRC may underestimate the ozone formation potential of benzene.

[Smog chamber simulation of ozone formation from atmospheric photooxidation of propane].

Atmospheric photochemical reactions of propane and NO, were simulated with a self-made smog chamber. The effects of relative humidity (RH) and [C3H8]0/[NOx]0 ratio on ozone formation were studied. The results showed that both the maximum ozone concentration and the maximum value of incremental reactivity (IRmax) of propane decreased linearly with increasing RH. Under lower RH conditions, the occurrence time of peak ozone concentration was about 22 h after the beginning of reaction, and IRmax varied from 0.0231 to 0.0391, while under higher RH conditions the occurrence time of peak ozone concentration was 16 h, and IRmax ranged from 0.0172 to 0.0320. During the 20 h of reaction, within the first 12 h RH did not significantly affect the yield of acetone, whereas after 12 h the lower RH condition could lead to relatively greater amount of acetone. During the first 4-20 h of experiments, acetone concentrations ranged from 153 x 10(-9) to 364 x 10(-9) at 17% RH and from 167 x 10(-9) to 302 x 10(-9) at 62% RH, respectively. Maximum ozone concentrations decreased with increasing [C3H8]0/[NOx]0 ratio and a better negative linear relationship between them was obtained under the lower RH conditions. The smog chamber data and the results from simulation of the C3H8-NOx reactions using the sub-mechanism of MCM were compared, and a significant deviation was found between these two results.

[Characterization of photochemical smog chamber and initial experiments].

A self-made new indoor environmental chamber facility for the study of atmospheric processes leading to the formation of ozone and secondary organic aerosols has been introduced and characterized. The characterization experiments include the measurements of wall effects for reactive species and the determination of chamber dependent * OH radical sources by CO-NO(x) irradiation experiments. Preliminary ethene-NO(x) and benzene-NO(x) experiments were conducted as well. The results of characterization experiments show that the wall effects for O3 and NO2 in a new reactor are not obvious. Relative humidity has a great effect on the wall losses in the old reactor, especially for O3. In the old reactor, the rate constant for O3 wall losses is obtained to be 1.0 x 10(-5) s(-1) (RH = 5%) and 4.0 x10(-5) s(-1) (RH = 91%), whereas for NO2, it is 1.0 x 10(-6) s(-1) (RH = 5%) and 0.6 x 10(-6) s(-1) (RH = 75%). The value for k(NO2 --> HONO) determined by CO-NO(x) irradiation experiments is (4.2-5.2) x 10(-5) s(-1) and (2.3-2.5) x 10(-5) s(-1) at RH = 5% and RH 75% -77%, respectively. The average *OH concentration is estimated to be (2.1 +/- 0.4) x 10(6) molecules/cm3 by using a reaction rate coefficient of CO and * OH. The sensitivity of chamber dependent auxiliary reactions to the O3 formation is discussed. Results show that NO2 --> HONO has the greatest impact on the O3 formation during the initial stage, N2O5 + H2O --> 2HNO3 has a minus effect to maximum O3 concentration, and that the wall losses of both O3 and NO2 have little impact on the O3 formation. The results from the ethene-NO(x) and benzene-NO(x) experiments are in good agreement with those from the MCM simulation, which reflects that the facility for the study of the formation of secondary pollution of ozone and secondary organic aerosols is reliable. This demonstrates that our facility can be further used in the deep-going study of chemical processes in the atmosphere.

Different magnitude of resistance to nondepolarizing muscle relaxants in the denervated mouse skeletal muscle.

AIM: To test the hypothesis that different magnitude of resistance of denervated skeletal muscle to nondepolarizing muscle relaxants (NDMRs) is related to their varying potencies at epsilon-AChR and gamma-AChR. METHODS: Both innervated and denervated mouse muscle cells, and human embryonic kidney 293 (HEK293) cells expressing epsilon-AChR or gamma-AChR were used. The effects of NDMRs on nAChR were explored using whole-cell patch clamp technique. RESULTS: NDMRs vecuronium (VEC), atracurium (ATR) and rocuronium (ROC) produced reversible, dose-dependent inhibition on the currents induced by 30 micromol/L acetylcholine both in innervated and denervated skeletal muscle cells. Compared to those obtained in innervated skeletal muscle cells, denervation shifted the concentration-response curves rightward and significantly increased the 50% inhibitory concentration (IC(50)) values (VEC: from 11.2 to 39.2 nmol/L, P<0.01; ATR: from 24.4 to 129.0 nmol/L, P<0.01; ROC: from 37.9 to 101.4 nmol/L, P<0.01). In HEK293 cell expression system, ATR was less potent at gamma-AChR than epsilon-AChR (IC(50) values: 35.9 vs 22.3 nmol/L, P<0.01), VEC was equipotent at both receptor subtypes (IC(50) values: 9.9 vs 10.2 nmol/L, P>0.05), while ROC was more potent at gamma-AChR than epsilon-AChR (IC(50) values: 22.3 vs 33.5 nmol/L, P<0.05). CONCLUSION: Magnitude differences of resistance to different NDMRs caused by denervation are associated with distinct potencies of NDMRs at nAChR subtypes.

[Study of the "weekend effect" of O3, NOx and other pollutants in summer of Beijing].

The data of O3, NOx (NO and NO2), CO and SO2 observed at Beijing 325m meteorological tower from June 25 to July 7, 2000 and from July 26 to August 22, 2000 are used to analyze the difference of pollutant concentrations on weekends and weekdays, and its causes. Results show that except SO2, the correlations of O3, NOx, NO, NO2 and CO concentrations between weekends and weekdays are very significant,since they all pass the t-test significance level at alpha = 0.05. The correlation coefficients (R) are 0.99, 0.61, 0.56, 0.80 and 0.61 for O3, NOx, NO, NO2 and CO3, respectively. Weekend NO, and CO concentrations are lower than weekday concentrations in rush hours (06:00-08:00), and the mean deviations for NOx and CO concentrations are -28% and -9%, respectively. The regression coefficient of O3 concentrations between weekends and weekdays is 1.25 +/- 0.02. Furthermore, the maximum 1-h average O3 concentration and maximum 8-h average O3 concentration on weekends are 23% and 26% higher than those on weekdays, respectively, indicating an obvious O3 "weekend effect".

[Smog chamber simulation of atmospheric photochemical reactions of acetylene and NO(x)].

A series of characteristic experiments were conducted in a self-made photochemical smog chamber, which was used to simulate atmospheric photochemical reactions of acetylene and NO(x) under room temperature of (20 +/- 1) degrees C. The effect of acetylene and NO(x) on ozone production by photochemical reactions was discussed. The wall decay of O3 and NO2 were determined, which were 5.80 x 10(-6) s(-1) and 2.41 x 10(-6) s(-1), respectively. Such decay should be omitted relative to O3 and NO2 in simulative experiments. The effective light intensity for a single black lamp of 40 W was determined to be 0.64 x 10(-3) s(-1), which was expressed by the photolysis rate of NO2. The effect of different light intensity, initial concentrations of acetylene and NO(x) on O3 production was discussed after correction of background O3 from purified air. The incremental reactivity (IR) of acetylene were calculated. For four different experiments, the maximum values of IR are 1.76 x 10(-2), 2.68 x 10(-2), 2.04 x 10(-2) and 2.84 x 10(-2), respectively. It is found that there are close relationships between IR and initial acetylene concentrations, and between IR and irradiation intensity, and that there is no significant relation between IR and initial NO(x) concentrations.