Structural characterization of lipidic systems under nonequilibrium conditions

This review covers recent studies on the characterization of the dynamics of lipidic nanostructures formed via self-assembly processes. The focus is placed on two main topics: First, an overview of advanced experimental small-angle X-ray scattering (SAXS) setups combined with various sample manipulation techniques including, for instance, stop-flow mixing or rapid temperature-jump perturbation is given. Second, our recent synchrotron SAXS findings on the dynamic structural response of gold nanoparticle-loaded vesicles upon exposure to an ultraviolet light source, the impact of rapidly mixing negatively charged vesicles with calcium ions, and in?situ hydration-induced formation of inverted-type liquid-crystalline phases loaded with the local anesthetic bupivacaine are summarized. These in?situ time-resolved experiments allow real-time monitoring of the dynamics of the structural changes and the possible formation of intermediate states in the millisecond to second range. The need for investigating self-assembled systems, mainly stimuli-responsive drug nanocarriers, under nonequilibrium conditions is discussed. For pharmaceutically relevant applications, it is essential to combine these investigations with appropriate in?vitro and in?vivo studies.     

Intranuclear dynamics of chromosome 6 in nurse cells of <Emphasis Type="Italic">Calliphora erythrocephala</Emphasis> Mg. (Diptera: Calliphoridae)

Intranuclear dynamics of chromosome 6 in nurse cell nuclei of Calliphora erythrocephala Mg. (Diptera: Calliphoridae) was studied. The 3D FISH method was used for the first time to study chromosome territories in highly polyploid nuclei whose chromosomes undergo morphological changes. A considerable change in the intranuclear location of chromosome 6 and a morphological alteration of the chromosome territory in the course of chromatin polytenization were revealed.     

Acetaminophen-induced antinociception via central 5-HT(2A) receptors.

Acetaminophen is one of the most widely used analgesic drugs. Although the mechanism of analgesic action of acetaminophen is still not known, the involvement of the central serotonin (5-hydroxytryptamine: 5-HT) system is one possibility. In the present study, we examined the antinociceptive effect of acute and chronic intraperitoneally (i.p.) administered acetaminophen by tail flick latency measurements in the rat. A significantly increased tail flick latency was observed in acute and 15-day acetaminophen-treated rats, but not in 30-day acetaminophen-treated rats, at a dose of 400 mg/kg/day. To investigate the plasticity of receptors at postsynaptic membrane, we conducted a series of experiments by radioligand binding method on frontal cortex and brainstem membrane. The technique involved radioligand binding with [phenyl-4-³H]spiperone and ketanserin for studying 5-HT_2A receptor characteristics. A significant decrease in the maximum number of 5-HT_2A binding sites (B_max) was demonstrated in all treatment groups with acetaminophen 300 and 400 mg/kg on frontal cortex membrane, whereas the value of the dissociation equilibrium constant (K_d) remained unchanged. The down-regulation of 5-HT_2A binding sites in frontal cortex was of a lesser magnitude after 30 days of treatment and the tail flick latency was as in the control animals. These results suggest that down-regulation of 5-HT_2A receptor in response to 5-HT release is a major step in the mechanism underlying analgesia produced by this agent. On the contrary, chronic use of acetaminophen may result in 5-HT depletion, which in turn produces re-adaptation of postsynaptic 5-HT_2A receptors. These data provide further evidence for a central 5-HT-dependent antinociceptive effect of acetaminophen.     

人乳汁中microRNA的稳定性研究

为了研究人乳汁中的microRNAs(miRNAs)在体外储存状态下的稳定性。本研究采用模拟体外乳汁储存条件,对乳汁进行室温孵育24h,反复冻融6次,100℃孵育10min,以及模拟体内消化环境(RNA酶A/T137℃孵育1h)的处理条件,通过实时荧光定量PCR(qRT-PCR)方法检测处理前后乳汁中9个内源性免疫相关和1个外源性人工合成miRNA的相对表达量变化差异。研究结果显示:处理前后乳汁中内源性miRNAs和外源性miRNA均显著性降解(p<0.01)。内源性miRNAs降解为初始量的25%～70%之间,而外源性miRNA则急剧降解至初始量的0.06%～0.96%。我们的实验表明人乳汁中内源性的miRNAs较外源性miRNAs在体外不同环境下具有更强的稳定性。     

西鄂尔多斯4种荒漠植物光合作用特征与差异性

植物对光能的高效吸收、传递和转换机理是光合作用的核心。为了厘清西鄂尔多斯地区4种荒漠植物光合生理生态适应性和生境适宜性,运用LI-6800光合作用测定系统对四合木(Tetraena mongolica)、霸王(Sarcozygium xanthoxylon)、沙冬青(Ammopiptanthus mongolicus)和白刺(Nitraria tangutorum)进行光合作用日变化进行了测定。研究结果表明:(1) 4种荒漠植物的光合作用日变化的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO_2浓度(Ci)均表现出明显的分异;(2)净光合速率均呈"双峰"曲线的变化趋势,4种荒漠植物的净光合速率(Pn)依次排序为四合木(4.37μmol m~(-2) s~(-1))霸王(3.58μmol m~(-2) s~(-1))沙冬青(2.63μmol m~(-2) s~(-1))和白刺(2.26μmol m~(-2) s~(-1))。说明四合木和近缘种霸王比其他二种荒漠植物具有较强的光合生理生态适应性与生境适宜性;(3)从影响光合作用的有关生理生态因子来看,净光合速率与气孔导度与蒸腾速率、水分利用效率呈现明显的正相关性,与微气象因子大气相对湿度(RH)的相关性不明显;(4)水分因子是限制4种荒漠植物生长的重要因素之一。该研究以期为我国西北荒漠区珍稀濒危植物的保护提供案例借鉴与理论依据。