Cultured human fibroblasts as a model for evaluation of potential in vivo toxicity of membrane damaging antibiotics

The toxic side effects of certain antimicrobial agents are probably related to their membrane damaging properties. Thus it should be possible to use measurement of membrane damage in vitro for evaluation of the potential toxicity in vivo of such antibiotics. We estimated the membrane damage induced in cultured human fibroblasts by anti-microbial agents, such as polyene antibiotics, sodium fusidate and polymyxin B as well as derivatives of some of these. Degree and character of membrane damage was determined on basis of leakage of three defined cytoplasmic markers from prelabelled cells after treatment with test substance.By comparing the minimal inhibitory concentrations against the target microbial cells (MIC) with the amounts needed to cause membrane damage of human cells (ED₅₀) a ‘therapeutic dose range’ was obtained (ED₅₀/MIC). The therapeutic dose range and the character of induced membrane damage were compared with the relative toxicities in vivo of each test substance. Highly toxic agents caused large functional ‘holes’ and/or showed a narrow therapeutic dose range, whereas less toxic substances induced smaller functional holes and/or had a larger therapeutic dose range. These parameters, evaluated in the presented model system, should be useful for an indication of potential toxicity in vivo.     

最小成本为目标函数时最优循环量的确定

由于超滤无相变,操作条件温和,能耗低等优点,使其在生物医药领域取得日益广泛的应用,尤其在价格昂贵的生物制品等热敏性生物活性物质的分离、浓缩和纯化中显示出极大优越性,已引起人们的广泛重视。然而,超滤优势的充分发挥受到许多因素的制约。在影响超滤的众多操作因素中,保留液循环量即膜面速度是其中最重要的因素之一,特别是当膜应用于中试或工业化生产后,最优循环量(膜面     

Traffic of botulinum toxins A and E in excitatory and inhibitory neurons

Botulinum neurotoxins (BoNTs), proteases specific for the SNARE proteins, are used to study the molecular machinery supporting exocytosis and are used to treat human diseases characterized by cholinergic hyperactivity. The recent extension of the use of BoNTs to central nervous system (CNS) pathologies prompted the study of their traffic in central neurons. We used fluorescent BoNT/A and BoNT/E to study the penetration, the translocation and the catalytic action of these toxins in excitatory and inhibitory neurons. We show that BoNT/A and BoNT/E, besides preferentially inhibiting synaptic vesicle recycling at glutamatergic relative to Gamma-aminobutyric acid (GABA)-ergic neurons, are more efficient in impairing the release of excitatory than inhibitory neurotransmitter from brain synaptosomes. This differential effect does not result from a defective penetration of the toxin in line with the presence of the BoNT/A receptor, synaptic vesicle protein 2 (SV2), in both types of neurons. Interestingly, exogenous expression of SNAP-25 in GABAergic neurons confers sensitivity to BoNT/A. These results indicate that the expression of the toxin substrate, and not the toxin penetration, most likely accounts for the distinct effects of the two neurotoxins at the two types of terminals and support the use of BoNTs for the therapy of CNS diseases caused by the altered activity of selected neuronal populations.     

金环蛇蛇毒对S180,EAC腹水癌细胞的细胞毒性作用

目的　探讨金环蛇毒对 S1 80 ,EAC腹水癌细胞的细胞毒性作用。　方法　采用小白鼠腹腔和皮下接种 S1 80 ,EAC腹水癌细胞造成小白鼠腹水模型后腹腔注射金环蛇毒。　结果　腹腔注射金环蛇毒 ,能抑制肿瘤细胞的生长 ,降低接种率。但不能完全控制腹水和癌细胞的生长。体外试验表明有明显的细胞毒作用。台酚蓝染色镜检可见死细胞显著增加 ,腹水图片检查给药后细胞膜破裂 ,纤维化坏死明显。　结论　能延长小白鼠存活时间。     

Intracellular solute gradients during osmotic water flow: An electron-microprobe analysis

Summary In an attempt to quantify possible intracellular water activity gradients during ADH-induced osmotic water flow, we employed energy dispersive X-ray microanalysis to thin, freezedried cryosections obtained from fresh, shock-frozen tissue of the toad urinary bladder. The sum of all detectable small ions (Na + K + Cl) in the cellular water space was taken as an index of the intracellular osmolarity. Presuming that all ions are osmotically active, they comprise about 90% of the cellular solutes. When the cells were exposed to dilute serosal medium, the reduction in the sum of the ions agreed well with the expected reduction in osmolarity. After inducing water flow by addition of ADH and dilution of the mucosal medium, all epithelial cells showed a fall in osmolarity. The change was more pronounced in granular cells than in basal or mitochondria-rich cells, consistent with the notion that granular cells represent the main transport pathway. Most significantly, intracellular osmolarity gradients, largely caused by an uneven distribution of K and Na, were detectable in granular cells. The gradients were not observed after ADH or mucosal dilution alone, or when the direction of transepithelial water flow was reversed. We conclude from these results that there is a significant cytoplasmic resistance to water flow which may lead to intracellular gradients of water activity. Concentration gradients of diffusible cations can be explained by a flow-induced Donnan-type distribution of fixed negative charges. With regard to transepithelial Na transport, the data suggest that ADH stimulates transport by increasing the Na permeability of the apical membranes of granular cells specifically.     

Clinical associations of serum interleukin-17 in systemic lupus erythematosus

Introduction

Serum interleukin (IL)-17 concentrations have been reported to be increased in systemic lupus erythematosus (SLE), but associations with clinical characteristics are not well understood. We characterized clinical associations of serum IL-17 in SLE.

Methods

We quantified IL-17 in serum samples from 98 SLE patients studied cross-sectionally, and in 246 samples from 75 of these patients followed longitudinally over two years. Disease activity was recorded using the SLE Disease Activity Index (SLEDAI)-2k. Serum IL-6, migration inhibitory factor (MIF), and B cell activating factor of the tumour necrosis factor family (BAFF) were also measured in these samples.

Results

Serum IL-17 levels were significantly higher in SLE patients compared to healthy donors (P <0.0001). No correlation was observed between serum IL-17 and SLEDAI-2k, at baseline or during longitudinal follow-up. However, we observed that SLEDAI-2k was positively correlated with IL-17/IL-6 ratio. Serum IL-17 was significantly increased in SLE patients with central nervous system (CNS) disease (P = 0.0298). A strong correlation was observed between serum IL-17 and IL-6 (r = 0.62, P <0.0001), and this relationship was observed regardless of disease activity and persisted when integrating cytokine levels over the period observed (r = 0.66, P <0.0001). A strong correlation of serum IL-17 was also observed with serum BAFF (r = 0.64, P <0.0001), and MIF (r = 0.36, P = 0.0016).

Conclusions

Serum IL-17 concentration correlates poorly with SLE disease activity but is significantly elevated in patients with CNS disease. IL-17/IL-6 ratio may be more useful than IL-17 or IL-6 alone to characterize Th17-driven disease, such as SLE. The association of other cytokines with serum IL-17 suggests that IL-17 may drive activation of diverse immune pathways in SLE.     

白色麝香霉挥发性有机化合物的抗菌活性和组成分析

采用核糖体RNA转录间隔区(internal transcribed spacer of ribosomal RNA,ITS r RNA)、RNA聚合酶II(RNA polymerase II,rpb2)和β-维管蛋白(beta-tubulin,tub1)基因系统发育分析法,鉴定了一株分离自浙江庆元的麝香霉ZJQY709,鉴定结果表明该菌为白色麝香霉Muscodor albus。生长速率法测定结果显示该菌株最适生长温度为22–28℃。二分格培养皿对峙培养法测定该菌挥发性有机化合物的抑菌活性,结果表明其挥发性有机化合物对灰葡萄孢菌和立枯丝核菌的生长抑制作用较强,而对尖孢镰刀菌和终极腐霉的抑制作用较弱。固相微萃取/气质联用法分析该菌产生的挥发性有机化合物,结果显示其挥发性有机化合物成分复杂,主要气体成分为2-甲基丙酸、乙酸-2-甲基丙酯和1-丁醇-2-甲基乙酸。     

苦参凝集素的分离纯化及部分性质研究

从苦参 (SophoraflavescensAit.)根浸出液经硫酸铵分级 ,得苦参凝集素 (SFL)粗品 ,再经DEAE_Sepharose、SephadexG_1 5 0和HPLC层析 ,获得具有强凝集活性的SFL样品 ,用PAGE和SDS_PAGE检测均为单一蛋白染色带。SDS_PAGE显示SFL分子仅有一条肽链 ,SephadexG_1 0 0和SDS_PAGE测得其分子量均为 32kD。当SFL浓度为 0 .97μg/mL时能凝集兔红细胞 ,无血型专一性 ,其凝血活性可被甘露糖和果糖抑制 ,麦芽糖和葡萄糖有弱的抑制作用 ,凝集素分子含有 2 .89%的中性糖 ;当SFL量为 6 2 μg时 ,对棉花枯萎病菌 (FusariumvasinfectumAtk .)、小麦赤霉病菌(Gibberllasaubinetii (Mont.)Sacc .)和水稻稻瘟病菌 (PiriculariaoryzaeCav)菌丝体的生长发育有明显地抑制作用。用Edman法在蛋白测序仪上测出SFL的N端肽链 30个氨基酸的排列顺序为 :T/A/VDXLXFTFSDFDP NGEDLLFQGDAHVTSNN。     

家兔外膝体神经元回路的研究

家兔的视觉系统有其特色,其外膝体的解剖和生理特性与猫的情况有所不同。本文综述了家兔外膝体神经元回路研究的进展,特别是关于返回抑制回路的组成和机能意义为研究进展,并以此为例说明丘脑-大脑皮层的复杂相关关系。     

Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists; however, their distributions are rarely determined in tandem. Here we have examined the vertical distribution of AOA and anammox bacteria through the Arabian Sea oxygen minimum zone (OMZ), one of the most intense and vertically exaggerated OMZs in the global ocean, using a unique combination of intact polar lipid (IPL) and gene-based analyses, at both DNA and RNA levels. To screen for AOA-specific IPLs, we developed a high-performance liquid chromatography/mass spectrometry/mass spectrometry method targeting hexose-phosphohexose (HPH) crenarchaeol, a common IPL of cultivated AOA. HPH-crenarchaeol showed highest abundances in the upper OMZ transition zone at oxygen concentrations of ca. 5 μ, coincident with peaks in both thaumarchaeotal 16S rDNA and amoA gene abundances and gene expression. In contrast, concentrations of anammox-specific IPLs peaked within the core of the OMZ at 600 m, where oxygen reached the lowest concentrations, and coincided with peak anammox 16S rDNA and the hydrazine oxidoreductase (hzo) gene abundances and their expression. Taken together, the data reveal a unique depth distribution of abundant AOA and anammox bacteria and the segregation of their respective niches by >400 m, suggesting no direct coupling of their metabolisms at the time and site of sampling in the Arabian Sea OMZ.