Elevated NO2 damages the photosynthetic apparatus by inducing the accumulation of superoxide anions and peroxynitrite in tobacco seedling leaves.

This study aimed to further understand the toxicity of high concentrations of nitrogen dioxide (NO2) to plants, especially to plant photosynthesis. Tobacco plants in the six-leaf stage were exposed to 16.0 µL L-1 NO2 to determine the activities of photosystem II (PSII) and photosystem I (PSI) reaction centers, the blocking site of PSII electron transport, the degree of membrane peroxidation and the relative expression of PsbA, PsbO and PsaA genes in the third fully expanded leaves by using gas exchange and chlorophyll fluorescence techniques, biochemical and RT-PCR analysis. The results showed that 16.0 µL L-1 NO2 caused necrotic lesions to form on leaves and significantly increased the generation rate of superoxide anions (O2-) and the content of peroxynitrite (ONOO-) in leaves of tobacco seedling, leading to damage to cell membrane, chlorophyll content and net photosynthetic rate reduction, and photosynthetic apparatus destruction. Fumigation with 16.0 µL L-1 NO2 decreased the activity of PSII reaction center and oxygen evolution complex, and the relative expression of PabA in leaves of tobacco seedlings to inhibit the electron transport from the donor side to the receptor side of PSII, especially blocking the electron transport from QA to QB on the receptor side. The activity of the PSI reaction center and the relative expression of PsaA decreased, weakening the ability to accept electrons and inhibiting the electron transfer from PSII to PSI, which further increased the damage of PSII of tobacco seedling leaves caused by 16.0 µL L-1 NO2. Therefore, 16.0 µL L-1 NO2 leaded to the accumulation of O2- and ONOO-, which damaged the cell membrane and thylakoid membrane, inhibit the electron transport, and destroyed the photosynthetic apparatus in leaves of tobacco seedlings. The results from this study emphasized the importance of reducing the NO2 concentration in the atmosphere.

Reduction in thyroid dose from neck CT angiography with 64-slice spiral CT with automatic tube current modulation technique / 中华放射医学与防护杂志

Objective To assess the effectiveness of Z-axis automatic tube current modulation ( ATCM) technique with respect to dose reduction and image noise in the thyroid regional tissues during neck computed tomography angiography (CTA). Methods A total of 140 patients underwent neck CTA with 64-slice spiral CT, and were randomized into fixed-tube current group and ATCM group. Objective noise, CTDIw, DLP and mA of each group were recorded. Results The image qualities of all the patients were diagnostically acceptable, though the objective noise of neck in the ATCM group was higher than that in the group of fixed-tube current (P＜ 0.05 ). The radiation doses in the ATCM group [ CTDIw (35.99±1.31 ) mGy, DLP (11 121.39 ±5.51) mGy·cm] were significantly inferior to those in the group of fixed tube current [ CTDIw (43.22±1.42) mGy, DLP (1514.45±5.56) mGy·cm]. Conclusions Compared with fixedtube current technique, ATCM technique could significantly reduce the radiation dose in neck CT with diagnostic acceptability of the image quality.

Clinical analysis of 98 patients with gastric proximal cancer / 临床外科杂志

Objective To study the relation between th e administration of surgical operation for the stomach proximal tumor and the sa rvival time.Methods The operation pathes and ways were cho se according to the tumor＇s size, distance to the cardia and the general sitacet ion of the patients. The patients effected a radical cure were 84, among which , total stomach excision 31 cases , upper half stomach excision 42 cases , lower half stomach excision 11 cases; by abdomen incision 72 cases , by chest abdomen combination incision 8 cases, by chest incision 4 cases. These patients receiv ed routine FM chemotherapise after operation and were compared with 14 patients received only chemotherapies or failed to excision.Results 84 patients with stomach tumor effected a radical cure didn＇t occure death rel ation to operation . After 1,3,5 years following visit , the survival ratio o f 84 patients received surgical operation was 84,44 and 26 cases respectively, the 5 years survival ratio was 30.9%. 14 patients who did not recieve surgical o peration or failed to excision died within 3-11 months exclusively.Con clusions The stomach proximal tumor excision could prolong the pati ents survival time. The early tumor excision is more effective.