Novel hexacyclic camptothecin derivatives. Part 1: synthesis and cytotoxicity of camptothecins with an A-ring fused 1,3-oxazine ring

A novel series of A-ring modified hexacyclic camptothecin derivatives containing a 1,3-oxazine ring were first designed and synthesized. All of the hexacyclic camptothecins were assayed for in vitro cytotoxicity against nine human cancer cell lines. Among these compounds, 9b and 9c showed most potent cytotoxicity against several cell lines. Particularly, 9c was about 13-fold more potent than camptothecin, and about sixfold more potent than topotecan toward HEPG-2. Furthermore, it was also found that the N-alkyl substituted derivatives were more potent than the N-aryl and N-benzyl substituted compounds against most cell lines.     

Characteristics of an endophytic pyrene-degrading bacterium of Enterobacter sp. 12J1 from Allium macrostemon Bunge

One pyrene-degrading endophytic bacterium was isolated from plants grown in polycyclic aromatic hydrocarbon-contaminated soils and identified as Enterobacter sp. 12J1 based on the 16S rDNA gene sequence analysis. Heavy metal and antibiotic resistance, degradation of pyrene, solubilization of inorganic phosphate and cell surface hydrophobicity characteristics of the isolate were further characterized. The isolate was also evaluated for promoting plant growth of wheat and maize and pyrene removal from pyrene-amended soil in pot experiments. High-performance liquid chromatograph (HPLC) analysis showed that the degradation rate of pyrene (5 mg l⁻¹) by the endophytic bacterial strain 12J1 was 83.8% under 28 °C for 7 days. The Enterobacter sp. 12J1 could produce indole acetic acid (IAA), siderophore and solubilize inorganic phosphate. The Enterobacter sp. 12J1 also has a cell surface hydrophobicity. In the live bacterial inoculation experiment, an increase in pyrene removal varying from 60% to 107% was observed in the planted soils treated with 100 mg kg⁻¹ of pyrene compared with the unplanted soils. The rate of pyrene removal increased by 43–65% in the live bacterium-inoculated planted soils compared with the dead bacterium-inoculated planted soils. Although there were no significant differences in the total culturable bacterial numbers between live and dead bacterial inoculation, the numbers of pyrene-degrading bacteria were significantly greater in the live bacterium-inoculated planted or unplanted soils. The isolate could colonize the tissue (root and stem) interiors and rhizosphere soils of wheat and maize after root inoculation.     

2-Phenoxy-indan-1-one derivatives as acetylcholinesterase inhibitors: a study on the importance of modifications at the side chain on the activity

As a part of our project aimed at developing new agents of potential application in AD, a new series of 2-phenoxy-indan-1-one derivatives which possess alkylamine side chain were designed, synthesized, and evaluated for their inhibitory activity against AChE and BuChE. Most of the compounds were found to inhibit AChE in the nanomolar range. The optimum inhibitor 3g exhibited 34-fold increase in AChE inhibition than donepezil and displayed neuroprotective effect against H(2)O(2)-induced cell death.     

中西医结合救治毒蛇咬伤致急性呼吸衰竭的临床观察

目的 探讨中西医结合救治毒蛇咬伤致急性呼吸衰竭的治疗效果.方法 应用中西医结合的方法(机械通气、抗蛇毒血清结合中医中药)救治46例毒蛇咬伤致急性呼吸衰竭患者.结果 46例全部痊愈出院.结论 中西医结合治疗措施是救治毒蛇咬伤致急性呼吸衰竭的最有效方法.     

不同分子量壳聚糖对五种常见茵的抑制作用研究

体外抑菌法研究了六种不同相对分子量的壳聚糖对金黄色葡萄球菌、大肠杆菌、绿脓杆菌、白色念珠菌、变形杆菌的抑菌活性,并对壳聚糖的抑菌机理做了探讨.     

不同光质光对葡萄愈伤组织增殖和白藜芦醇含量的影响

研究不同光质影响‘黑比诺’种子诱导并继代10个月的葡萄愈伤组织增殖及白藜芦醇含量的结果表明：不同光质下愈伤组织的增殖顺序依次为黄光〉绿光〉红光〉蓝光〉白光;白藜芦醇的含量依次为白光〉黄光〉红光〉蓝光〉绿光：白藜芦醇的生产量是白光〉黄光〉红光〉蓝光〉绿光。     

保幼激素的分子作用机制

蜕皮激素(ecdysteroids, Ecd)和保幼激素(juvenile hormone, JH)是调控昆虫发育和变态的两种最为重要的昆虫激素。尽管Ecd的分子作用机制已经相当明了,但是,因为迄今为止还没有成功地鉴定出JH受体,人们对JH的分子作用机制还了解甚少。本文从三个方面较为详尽地介绍了近年来JH分子作用机制的相关研究进展：1) JH和Ecd在分子水平上相互作用, JH可以通过改变或者抑制Ecd信号来调控昆虫的发育和变态;2) JH核受体的两个候选基因为Met和USP;3) JH还可以通过膜受体和蛋白激酶C传导信号。     

Color change as a potential behavioral strategy

Within species, color morphs may enhance camouflage, improve communication and/or confer reproductive advantage. However, in the male cichlid Astatotilapia burtoni, body color may also signal a behavioral strategy. A. burtoni live in a lek-like social system in Lake Tanganyika, Africa where bright blue or yellow territorial (T) males (together ~ 10–30% of the population) are reproductively capable and defend territories containing food with a spawning site. In contrast, non-territorial (NT) males are smaller, cryptically colored, shoal with females and have regressed gonads. Importantly, males switch between these social states depending on their success in aggressive encounters. Yellow and blue morphs were thought to be adaptations to particular habitats, but they co-exist both in nature and in the laboratory. Importantly, individual males can switch colors so we asked whether color influences behavioral and hormonal profiles. When pairing territorial males with opposite colored fish, yellow males became dominant over blue males significantly more frequently. Moreover, yellow T males had significantly higher levels of 11-ketotosterone than blue T males while only blue NT males had higher levels of the stress hormone cortisol compared to the other groups. Thus color differences alone predict dominance status and hormone profiles in T males. Since T males can and do change color, this suggests that A. burtoni may use color as a flexible behavioral strategy.     

Midge-inferred Holocene summer temperatures in Southeastern British Columbia,Canada

Using fossil midge stratigraphies, we inferred Holocene summer temperatures at three subalpine lakes in eastern British Columbia. The late-glacial sediment indicated cool conditions, with an abundance of Microspectra atrofasciata/radialis type fossils at Thunder Lake and Redmountain Lake, and Sergentia at Windy Lake. Sergentia and Tanytarsus lugens/Corynocera oliveri type were dominant in the early Holocene, together with Chironomus at Redmountain Lake. At Thunder and Windy lakes, the early Holocene was dominated by warm-adapted taxa such as Microtendipes. Quantitative midge-temperature inference models reconstruct a 4 to 8 °C rise in mean July air temperature for Windy and Thunder lakes at the Pleistocene/Holocene transition. Early-Holocene temperatures averaged 3 to 4 °C warmer than those extant today. In contrast, no long-term temperature trend was evident at Redmountain Lake. This site may not reflect actual trends in air temperature due to runoff from a persistent snow pack in the watershed. Comparison of midge and pollen data suggests an inverse relationship between summer temperature and precipitation through the middle to late Holocene.     

Restoration of mature etiolated cucumber hypocotyl cell wall susceptibility to expansin by pretreatment with fungal pectinases and EGTA in vitro

Mature plant cell walls lose their ability to expand and become unresponsive to expansin. This phenomenon is believed to be due to cross-linking of hemicellulose, pectin, or phenolic groups in the wall. By screening various hydrolytic enzymes, we found that pretreatment of nongrowing, heat-inactivated, basal cucumber (Cucumis sativus) hypocotyls with pectin lyase (Pel1) from Aspergillus japonicus could restore reconstituted exogenous expansin-induced extension in mature cell walls in vitro. Recombinant pectate lyase A (PelA) and polygalacturonase (PG) from Aspergillus spp. exhibited similar capacity to Pel1. Pel1, PelA, and PG also enhanced the reconstituted expansin-induced extension of the apical (elongating) segments of cucumber hypocotyls. However, the effective concentrations of PelA and PG for enhancing the reconstituted expansin-induced extension were greater in the apical segments than in the basal segments, whereas Pel1 behaved in the opposite manner. These data are consistent with distribution of more methyl-esterified pectin in cell walls of the apical segments and less esterified pectin in the basal segments. Associated with the degree of esterification of pectin, more calcium was found in cell walls of basal segments compared to apical segments. Pretreatment of the calcium chelator EGTA could also restore mature cell walls' susceptibility to expansin by removing calcium from mature cell walls. Because recombinant pectinases do not hydrolyze other wall polysaccharides, and endoglucanase, xylanase, and protease cannot restore the mature wall's extensibility, we can conclude that the pectin network, especially calcium-pectate bridges, may be the primary factor that determines cucumber hypocotyl mature cell walls' unresponsiveness to expansin.