An efficient, practical synthesis of 2-methoxyestradiol

An efficient and practical scheme to synthesize 2-methoxyestradiol has been developed. The key step was the copper-mediated methoxylation using ethyl acetate as a co-catalyst to introduce a methoxyl group. These synthetic procedures of four steps from 17β-estradiol as starting material gave 2-methoxyestradiol with a 61% overall yield.     

墨红鲜花香气(头香)成分分析

利用 XAD-4憎水性吸附树脂采集墨红头香,以毛细管气相色谱双柱保留指数和 GC/MS/DS 联用方法鉴定头香的化学成份。共分离鉴定或初步鉴定了45种组份,其中含量较大的有乙酸芳樟酯(14.98%),柠檬烯(12.07%),甲基苯甲醚(9.88%),香茅醇(4.82%),乙酸巳酯(3.98%),β-石竹烯(4.55%),芳樟醇(3.18%),正巳醇(3.17%)等.     

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and vitamin E (VE). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger than VE. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger than VE (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems. The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.     

Inhibited enzyme electrodes. Part 3: A sensor for low levels of H2S and HCN

It is shown that an inhibited enzyme electrode, using cytochrome oxidase, will respond to H₂S, HCN and azide ion. For all three inhibitors the kinetics of the inhibition and recovery processes have been analysed using the theoretical model presented previously (Albery et al., 1990a). Rearrangement of the differential equation describing inhibition and the development of the necessary software has enabled us to obtain values of the concentration of inhibitor in a matter of seconds after exposure of the sensor. The sensor will measure concentrations of H₂S down to 1 ppm in the gas phase and concentrations of HCN and azide ion down to 0·4 μmol dm⁻³ in the solution     

电刺激猫小脑顶核对动脉血压和肾交感神经放电的影响

在38只麻醉及人工呼吸的猫,观察到电刺激小脑顶核嘴侧部能引起动脉血压显著升高;肾交感神经放电于刺激期间显著增加。去缓冲神经对刺激顶核所引起的血压反应的幅度和肾交感神经放电均无明显影响,但可明显延长血压反应升高相以及血压恢复期的时间。静脉注射氯庄定引起血压降低、心率减慢及肾交感神经放电的抑制,并能减弱刺激顶核引起的血压反应,但增强了刺激顶核引起的肾神经放电的变化。电解损毁延髓腹外侧面引起血压降低及肾交感神经放电的抑制,然而无论单侧还是双侧损毁延髓腹外侧面都不能阻断刺激顶核所引起的血压和肾交感神经放电的反应。以上结果表明,电刺激顶核能引起明显的心血管反应,其反应的下行性通路可能不通过延髓腹外侧面。     

Occurrence of rye (Secale cereale) 350-family DNA sequences inAgropyron and otherTriticeae

Evidence is presented that in the R and P genomes (Secale cereale andAgropyron cristatum, respectively) of theTriticeae there exist closely related 350-family DNA sequences in the terminal heterochromatin. This observation is compared to the relationships between these two genomes derived from a comparison of theNor and5 S DNA loci as well as the available data on morphological characters, chromosome pairing, and isozyme studies. It is concluded that the R and P genomes are not closely related and that the common presence of very similar 350-family DNA sequences reflects the parallel amplification of this family of DNA sequences.     

Frequent duplication and deletion events in the 5S RNA genes and the associated spacer regions of theTriticeae

The 5 S DNA units from 15 grasses in theTriticeae were analysed at the DNA sequence level. Four units carried duplications near the 3-end of the 5 S RNA gene with 3 of the duplications centred on the same base pairs as a duplication previously reported byGerlach & Dyer. The fourth duplication was located 3 downstream from the gene, in the spacer region. Apparent deletions were very frequent when units of the different grasses were compared and it was clear that these deletions did not extend into a 75 bp spacer region upstream from the 5 S RNA gene. This 75 bp region also tended to be more conserved between the grasses as compared to the high level of sequence change in the rest of the spacer region. — Phenetic relationships were established between the grasses using the sequence data. The relationships were generally consistent with the data from other parameters and, in addition, showed that two Australian grasses were closely related to the other Northern hemisphere genera examined. The data concerning the Australian grasses is discussed in relation to the isolated nature of Australia.