Research progress in characterizing multiple-target mechanisms of novel anti-Alzheimer's dimers / 中国药理学通报

Alzheimer's disease ( AD ) is a complex disease caused by environmental and genetic factors. Therefore, one-drug-multiple-target compounds represent the most promising pharmacological approaches to preventing and treating this dis-ease. We have previously designed and synthesized bis( n)-Cog-nitin, novel anti-Alzheimer's dimers derived from tacrine. Bis ( n)-Cognitin have been proven to act on multiple important AD targets, including acetylcholinesterase, β-secretase, N-methyl-D-aspartic acid receptor and neuronal nitric oxide synthase, con-currently. Moreover, Bis(n)-Cognitin could inhibit β-amyloid-induced neurotoxicity, decrease glutamate-induced excitotoxici-ty, reduce oxidative stress, improve learning and memory, and protect against neuronal apoptosis in various in vitro and in vivo models, suggesting that bis ( n )-Cognitin are potential anti-AD drug candidates.

Water use by fast-growing Eucalyptus urophylla plantations in southern China.

Tree growth, water use, climate and soil water conditions were monitored over 12 months in two 3-4-year-old Eucalyptus urophylla S.T. Blake plantations on the Leizhou Peninsula of southern China. The Hetou plantation was established on a sandy soil of sedimentary origin with low water storage capacity, and the Jijia plantation was established on a clay soil formed on basalt. Sapwood area was approximately 50% higher at Jijia than at Hetou because of differences in plant spacing (1994 versus 1356 stems ha(-1)). Annual water use, assessed by heat pulse measurements, was 542 mm at Hetou and 559 mm at Jijia, with mean sap flux densities of 2772 and 1839 l m(-2) day(-1), respectively. Limitations to water use, imposed by climatic and soil factors, were quantified by analysis of daily canopy conductance in relation to daytime vapor pressure deficit (VPD) and soil water content. Similar annual water use at the two sites was a result of higher VPD and soil water availability at Hetou compensating for the greater sapwood area at Jijia. Potential annual water use in the absence of soil water limitation was estimated at 916 mm at Jijia and 815 mm at Hetou. Higher water availability during the dry season and early wet season at Hetou than at Jijia was the result of deep root systems. The results imply that water use by plantations on soils with high water availability and in areas of high VPD may be reduced by establishment at wider spacing. The environmental cost of water use by plantations must be weighed against their economic and environmental values to determine an appropriate mix of forestry, agriculture and other land uses in regions where water resources are limited.