Characterization of the pharmacokinetic disposition of levofloxacin in stallions after intravenous and intramuscular administration

The target of the present study was to investigate the plasma disposition kinetics of levofloxacin in stallions (n = 6) following a single intravenous (i.v.) bolus or intramuscular (i.m.) injection at a dose rate of 4 mg/kg bwt, using a two‐phase crossover design with 15 days as an interval period. Plasma samples were collected at appropriate times during a 48‐h administration interval, and were analyzed using a microbiological assay method. The plasma levofloxacin disposition was best fitted to a two‐compartment open model after i.v. dosing. The half‐lives of distribution and elimination were 0.21 ± 0.13 and 2.58 ± 0.51 h, respectively. The volume of distribution at steady‐state was 0.81 ± 0.26 L/kg, the total body clearance (Cl_tot) was 0.21 ± 0.18 L/h/kg, and the areas under the concentration–time curves (AUCs) were 18.79 ± 4.57 μg.h/mL. Following i.m. administration, the mean t_1/2el and AUC values were 2.94 ± 0.78 h and 17.21 ± 4.36 μg.h/mL. The bioavailability was high (91.76% ± 12.68%), with a peak plasma mean concentration (C_max) of 2.85 ± 0.89 μg/mL attained at 1.56 ± 0.71 h (T_max). The in vitro protein binding percentage was 27.84%. Calculation of efficacy predictors showed that levofloxacin might have a good therapeutic profile against Gram‐negative and Gram‐positive bacteria, with an MIC ≤ 0.1 μg/mL.     

基质分散固相萃取-QuEChERS耦合HPLC法测定棉花叶片中吡虫啉及其相关代谢物

建立了QuEChERS前处理的棉花叶片中吡虫啉及其代谢物含量的高效液相色谱（HPLC）分析方法。在QuEChERS前处理方法的基础上,确定了乙腈作为提取剂,盐析材料为1.00 g氯化钠、4.00 g无水硫酸镁、0.50 g柠檬酸二钠和1.00 g柠檬酸钠,净化材料为25 mg的N-丙基乙二胺（PSA）,在2%乙腈-甲醇∶水=3∶7条件下HPLC法进行定量测定。结果表明：棉花叶片中的吡虫啉及其4种代谢物吡虫啉脲、烯式吡虫啉、吡虫啉胍和6-氯烟酸的平均加标回收率为92.84%~110.90%,相对标准偏差（RSD）在0.15%~6.99%之间,检出限（LOD）分别为0.0044、0.042、0.0011、0.091 mg·kg^-1和0.0066 mg·kg^-1,定量限（LOQ）分别为0.015、0.19、0.0059、0.036 mg·kg^-1和0.028 mg·kg^-1。该分析方法前处理简便、快速、准确,可为棉花叶片中吡虫啉及其代谢物残留的测定提供参考。     

重金属单一污染对龙须草生长与生理生化特性的影响

试验研究了不同处理水平下Cd、Pb、Cu、Zn、As单一污染对龙须草生长和生理生化特性的影响。结果表明:龙须草地下部对重金属的抗性大干地上部,种植龙须草的污染土壤中Cd、Pb、Cu的土壤临界值可分别设定为10mg／kg、300mg／kg和100mg／kg;龙须草叶绿素含量随重金属处理浓度的增加呈先升后降趋势,但其总叶绿素含量和叶绿素a／b值均低于对照;龙须草SOD活性随Zn、As单一污染处理浓度的增加呈先升后降趋势,而随其他3种重金属处理浓度的增加呈下降趋势;龙须草CAT和POD的活性随As处理浓度的增加呈上升趋势,而随其他4种重金属处理浓度的增加呈先升后降趋势。     

Solar wind outflow and the chromospheric magnetic network

Observations of outflow velocities in coronal holes (regions of open coronal magnetic field) have recently been obtained with the Solar and Heliospheric Observatory (SOHO) spacecraft. Velocity maps of Ne7+ from its bright resonance line at 770 angstroms, formed at the base of the corona, show a relationship between outflow velocity and chromospheric magnetic network structure, suggesting that the solar wind is rooted at its base to this structure, emanating from localized regions along boundaries and boundary intersections of magnetic network cells. This apparent relation to the chromospheric magnetic network and the relatively large outflow velocity signatures will improve understanding of the complex structure and dynamics at the base of the corona and the source region of the solar wind.     

Physiochemical factors affecting the salt tolerance of Echinochloa crus-galli Beauv. var. formosensis Ohwi

The effects of NaCl-induced stress on physiochemical factors such as inorganic cations, proline, malondialdehyde (MDA) and polyamines were investigated in the gramineous weed, Echinochloa crus-galli Beauv. var. formosensis Ohwi ( E. crus-galli ) and rice ( Oryza sativa L. cv. Nipponbare). Growth inhibition at the 2nd leaf stage under salt stress was more severe in rice than in E. crus-galli . Water content in the 2nd leaves was also more severely decreased in rice, indicating that E. crus-galli was more salt-tolerant. After NaCl treatment, Na⁺ accumulated in the 2nd leaves of both plant species but not in their roots. Proline accumulation in the 2nd leaves was significantly higher in salt stressed E. crus-galli than in rice, suggesting the significance of proline production in the salt tolerance of this weed. Content of MDA of the rice increased more greatly with NaCl treatment than that in E. crus-galli . NaCl treatment affected polyamine metabolism of both plant species, but the response of each plant to salt stress was somewhat different, especially in the leaves. Leaf putrescine and spermidine contents were high in non-stressed plants in salt-sensitive rice, although rather lower in E. crus-galli in response to NaCl concentrations. These results indicate that an increase in proline and changes in polyamines relates to the salt tolerance of E. crus-galli .     

寒地水稻品质育种研究

针对目前黑龙江省水稻品质育种的现状,指出了黑龙江省水稻品质育种存在的问题,虽然大多数品种的直链淀粉含量、胶稠度、食味已达到国家二级优质米标准,但距离国家一级优质米标准还有一定差距。提出在坚持高产的前提下提高品质,黑龙江省的水稻品质育种要有所突破,需要在品质育种的基础理论研究上进行进一步探讨,在实现种质创新、育成优质超级稻品种和取得产量性状突破的基础上,使黑龙江省水稻品质育种再上一个新台阶。     

玉米铁微营养生物有效性与生物强化的研究进展

综述了玉米子粒中铁的分析方法、生物有效性及其影响因素、铁生物强化的传统与分子育种途径的研究进展,并对HarvestPlus项目与组织作了概略的介绍。