中国梨木虱分泌物中氨基酸的分离与分析

利用离子交换色谱法分离了中国梨木虱分泌物中的氨基酸;利用毛细管气相色谱法对梨木虱分泌物中氨基酸的三氯乙酰了酯衍生物进行了分析。用标准样对照定性,内标法定量。分泌物中共检出13种氨基酸。     

Sugar‐Based Synthesis of Tamiflu and Its Inhibitory Effects on Cell Secretion

Tamiflu is currently the most effective drug for the treatment of influenza, but the insufficient supply and side‐effects of this drug demand urgent solutions. We present a practical synthesis of Tamiflu by using novel synthetic routes, cheap reagents, and the abundantly available starting material D ‐glucal. The strategy features a Claisen rearrangement of hexose to obtain the cyclohexene backbone and introduction of diamino groups through tandem intramolecular aziridination and ring opening. In addition, this synthetic protocol allows late‐stage functionalization for the flexible synthesis of Tamiflu analogues. By using the synthesized Tamiflu and its active metabolite (oseltamivir carboxylate), we investigated their influences on neuroendocrine PC12 cells in various aspects. It was discovered that oseltamivir carboxylate significantly inhibits the vesicular exocytosis (regulated secretion) of PC12 cells, and suggests a mechanism underlying the Tamiflu side‐effects, in particular its possible adverse influences on neurotransmitter release in the central nervous system.     

Dopamine promotes formation and secretion of non-fibrillar alpha-synuclein oligomers

Parkinson's disease (PD) is characterized by selective and progressive degeneration of dopamine (DA)-producing neurons in the substantia nigra pars compacta (SNpc) and by abnormal aggregation of α-synuclein. Previous studies have suggested that DA can interact with α-synuclein, thus modulating the aggregation process of this protein; this interaction may account for the selective vulnerability of DA neurons in patients with PD. However, the relationship between DA and α-synuclein, and the role in progressive degeneration of DA neurons remains elusive. We have shown that in the presence of DA, recombinant human α-synuclein produces non-fibrillar, SDS-resistant oligomers, while β-sheet-rich fibril formation is inhibited. Pharmacologic elevation of the cytoplasmic DA level increased the formation of SDS-resistant oligomers in DA-producing neuronal cells. DA promoted α-synuclein oligomerization in intracellular vesicles, but not in the cytosol. Furthermore, elevation of DA levels increased secretion of α-synuclein oligomers to the extracellular space, but the secretion of monomers was not changed. DA-induced secretion of α-synuclein oligomers may contribute to the progressive loss of the dopaminergic neuronal population and the pronounced neuroinflammation observed in the SNpc in patients with PD.     

Photochemical Behavior of Lysozyme-4-(2-pyridylazo)-resorcinol Polymolecular Complex and Its Analytical Applications

It was first found that 4-(2-pyridylazo)-resorcinol (PAR) can combine with lysozyme forming a polymolecular complex, with the molar ratio of 1:12 (lysozyme/PAR) in the medium of acetate buffer (pH 6.0). The fluorescence spectra suggested that PAR molecules may produce self-aggregation, and it was suggested that there are interactions between lysozyme and PAR possibly mainly on the cooperation of hydrophobic, electrostatic actions and chelate bond. The coordination complex of lysozyme-PAR can cause an enhanced resonance light scattering (RLS) signal with the scattering peak located at 521 nm. The increment of RLS intensity was linear with the concentration of lysozyme over the range from 1 ng mL^-1 to 30.0 μg mL^-1, with the limit of detection of 0.3 ng mL⁻¹ (3σ, n = 5). Effect of experimental conditions, including temperature, pH, concentration of PAR, and the ionic strength on RLS were also tested. The proposed RLS method was successfully applied to analyze lysozyme in hen egg white, human saliva and tear samples without any special pretreatment. Compared with other methods, the proposed procedure is of high sensitivity and selectivity.     

An elegant nano-injection machinery for sabotaging the host: Role of Type III secretion system in virulence of different human and animal pathogenic bacteria

Various Gram-negative bacteria possess a specialized membrane-bound protein secretion system known as the Type III secretion system (T3SS), which transports the bacterial effector proteins into the host cytosol thereby helping in bacterial pathogenesis. The T3SS has a special needle-like translocon that can sense the contact with the host cell membrane and translocate effectors. The export apparatus of T3SS recognizes these effector proteins bound to chaperones and translocates them into the host cell. Once in the host cell cytoplasm, these effector proteins result in modulation of the host system and promote bacterial localization and infection. Using molecular biology, bioinformatics, genetic techniques, electron microscopic studies, and mathematical modeling, the structure and function of the T3SS and the corresponding effector proteins in various bacteria have been studied. The strategies used by different human pathogenic bacteria to modulate the host system and thereby enhance their virulence mechanism using T3SS have also been well studied. Here we review the history, evolution, and general structure of the T3SS, highlighting the details of its comparison with the flagellar export machinery. Also, this article provides mechanistic details about the common role of T3SS in subversion and manipulation of host cellular processes. Additionally, this review describes specific T3SS apparatus and the role of their specific effectors in bacterial pathogenesis by considering several human and animal pathogenic bacteria.     

三维激光扫描技术获取高精度DTM的应用研究

基于离心分离技术研制了微小力测试平台，测 试到蚂蚁在光滑玻璃上的水平吸附力可达40倍身体重量. 用扫描电子显微镜观察 了蚂蚁足的形态. 分析结果表明分泌液对吸附是很重要的，排除掉真空力、静电力等吸附机 制后，推断吸附力主要来源于由分泌液产生的垂直于表面方向的毛细作用力和平行 方向的黏性力. 用ANSYS分析表明垫子表面微褶皱可迅速排出液体. 这些研究可进 一步揭开昆虫的吸附机制.     

In vivo sweat film layer thickness measured with Fourier-domain optical coherence tomography (FD-OCT)

While human sweat secretion is accepted as a mechanism by which the body cools off, excessive sweating (hyperhidrosis) is now appreciated as a medical condition and the primary site for diagnosis is the palm of the hand. We propose sweat film layer thickness as a potential clinical diagnostic parameter when screening for excessive sweating. In this preliminary study we demonstrate the usefulness of Fourier-domain optical coherence tomography (FD-OCT) for measurement of sweat film thickness in vivo with micron-scale resolution on the hand of a human volunteer. FD-OCT has a superior image acquisition time and identification of active sweat glands, ducts and pores is also possible.     

中药复方和某种植物分泌液对脂质过氧化的抑制作用

利用发光测量法,研究了中药复方、植物分泌液(SL)和植物分泌液复方(SLIV)对Fe2+-亚麻油酸-BSA(牛血清白蛋白)和Fe2+-脑勺浆两个离体体系产生的脂质过氧化(LPO)有抑制作用,抑制程度与用药浓度有关.将中药复方应用于辐照模型,结果表明7Gy的γ射线辐照后小白鼠全血硒谷胱甘肽过氧化物酶(SeGSH-Px)活性降低,恢复缓慢,脑组织脂质过氧化加剧,而事先喂饲中药复方能显著提高SeGSH-Px水平,加速其活力恢复,增强脑组织抗氧化能力;将SL和SLIV应用于脑缺血重灌模型,结果显示沙土鼠脑缺血重灌后全血SeGSH-Px活力下降,血浆MDA上升,SeGSH-Px/MDA值降低,脑组织抗氧化能力下降,而事先喂饲SL、SLIV上述结果正相反,能明显提高机体的抗LPO能力.     

A scanning and transmission electron microscopic study of the development of the surface structure of neuroepithelial bodies in the mouse lung

Neuroepithelial bodies (NEBs) are groups of neuroepithelial (NE) cells that are localized on mounds on the bronchiolar epithelium of the lung. The present study examined NEBs in mice ranging in age from 2 days before birth to 80 days after birth. The position and surface architecture of NEBs was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In foetal mice, 2 days before birth, NEBs were distinguished from the rest of the bronchiolar epithelium by a slight elevation of non-ciliated Clara-like cells arranged in a cobbestone-like pattern. The exposed surface of the NEB was identified by small protrusions with regular microvilli intermittenly located at the base of deep clefts between the Clara-like cells. The surface of the Clara-like cells had fewer and smaller microvilli and could be easily distinguished from the apical surface of the NEB. Before birth, the surface of all of the apical cells was covered by regularly placed microville, however after birth some of the more prominently positional apical cells revealed a bare patch at the centre of the portion of apical cell exposed to the lumen of the lung. As the mice aged there was an increase in the number of apical cell protusions observed with centrally positioned bare patches. These two morphologically distinct surfaces of apical cells may have separate specialized functions. The exposed surfaces of apical cells were often observed in pairs and this feature has been observed in various sensory organs providing support for chemoreceptive function. However small bright spheres resembling vesicles were frequently observed on the lumenal surface of apical cells of the centrally placed bare patch. Transmission electron microscopy confirmed the presence of vesicles on the surface of apical cells and due to their location these vesicles were thought to contain a substance secreted into the lumen of the lung by apical cells. The significance of the bare region on the apical cells is not clear in terms of the proposed chemoreceptive function usually attributed to NEBs. It may be possible that the morphological changes observed in apical cells after birth are more appropriate for secretion of than for chemoreception. This is supported by the observation in the present study of vesicles lying on the lumenal surface of the bare region of the apical cell, however the mechanism for secretion of whoel vesicles is not clear and requires further investigation.     

Dendropsophin 1, a novel antimicrobial peptide from the skin secretion of the endemic Colombian frog Dendropsophus columbianus

In efforts to find new antimicrobial peptides (AMPs), we studied the skin secretion of the endemic Colombian frog Dendropsophus columbianus belonging to a genus that has not been investigated previously. From HPLC-fractionated secretion, we identified one peptide with slightly antibacterial activity. Its peptide sequence showed no sequence similarity to current annotated peptides. We named this novel peptide dendropsophin 1 (Dc1). Afterward, two analogues were designed (Dc1.1 and Dc1.2) to improve the cationic and amphipathic features. Then, their antiproliferative and cytotoxic properties were evaluated against several pathogens including bacteria, fungi, protozoa and also mammalian cells. Dc1 and its two analogues exhibited moderate antibacterial activities and no hemolytic and cytotoxic effects on mammalian cells. Analogue Dc1.2 showed slightly improved antibacterial properties. Their secondary structures were characterised using CD spectroscopy and Dc1.2 displayed a higher α-helix content and thermal stability compared to Dc1 and Dc1.1 in hydrophobic experimental conditions.