家兔腹泻生态疗法的实验观察

根据动物微生态学理论,将3株正常菌：嗜酸乳杆菌、两歧双歧杆菌、粪链球菌研制成复方生态制剂,对家免细菌性腹泻进行治疗试验。共治疗75例,治愈率为96．00％,比痢特灵对照组治愈率提高16．00％。该制剂价格低廉,无毒、副作用,使用安全可靠,是一种防治家免细菌性腹泻的较理想制剂。     

Selective response of various brain cell types during neurodegeneration induced by mild impairment of oxidative metabolism

Age-related neurodegenerative diseases are characterized by selective neuron loss, glial activation, inflammation and abnormalities in oxidative metabolism. Thiamine deficiency (TD) is a model of neurodegeneration induced by impairment of oxidative metabolism. TD produces a time-dependent, selective neuronal death in specific brain regions, while other cell types are either activated or unaffected. TD-induced neurodegeneration occurs first in a small, well-defined brain region, the submedial thalamic nucleus (SmTN). This discrete localization permits careful analysis of the relationship between neuronal loss and the response of other cell types. The temporal analysis of the changes in the region in combination with the use of transgenic mice permits testing of proposed mechanisms of how the interaction of neurons with other cell types produces neurodegeneration. Loss of neurons and elevation in markers of neurodegeneration are accompanied by changes in microglia including increased redox active iron, the induction of nitric oxide synthase (NOS) and hemeoxygenase-1, a marker of oxidative stress. Endothelial cells also show changes in early stages of TD including induction of intracellular adhesion molecule-1 (ICAM-1) and endothelial NOS. The number of degranulating mast cells also increases in early stages of TD. Alterations in astrocytes and neutrophils occur at later stages of TD. Studies with transgenic knockouts indicate that the endothelial cell changes are particularly important. We hypothesize that TD-induced abnormalities in oxidative metabolism promote release of neuronal inflammatory signals that activate microglia, astrocytes and endothelial cells. Although at early stages the responses of non-neuronal cells may be neuroprotective, at late phases they lead to entry of peripheral inflammatory cells into the brain and promote neurodegeneration.     

银杏叶提取物的微生物转化研究Ⅲ．转化产物的化学成分

为研究银杏叶提取物经微生物转化后的化学成分,采用微生物转化的方法对银杏叶提取物进行处理得到转化粗提物,采用硅胶、Sephadex^TM LH-20凝胶等色谱技术对转化粗提物进行分离纯化,通过波谱分析单体结构鉴定。结果发现,从银杏叶提取物的转化粗提物中分得5个化合物,分别为异鼠李素（isorhamnetin,1）、山奈酚（kaempferol,2）、斛皮素（quercefin,3）、山奈酚-3-O-α-L-鼠李糖苷（kaempferol-3-O-α-L-rhamnosid,4）、斛皮素-3-O-α-L-鼠李糖苷（quercetin-3-O-α-L-rhamnosid,5）。结果表明,这是首次用微生物转化的方法对银杏叶提取物进行处理。     

Structure-activity relationship analysis of a novel necroptosis inhibitor, Necrostatin-5

Necrostatin-5 (Nec-5) is a novel potent small-molecule inhibitor of necroptosis structurally distinct from previously described Necrostatin-1 (Nec-1), and therefore, represents a new direction for the inhibition of this cellular caspase-independent necrotic cell death mechanism. Here, we describe a series of structural modifications of Nec-5 and the structure-activity relationship (SAR) of Nec-5 series in inhibiting necroptosis.     

RGD targeted poly(L-glutamic acid)-cystamine-(Gd-DO3A) conjugate for detecting angiogenesis biomarker alpha(v) beta3 integrin with MRT, mapping

Cyclic Arg-Gly-Asp-D-Phe-Lys [c(RGDfK)] targeted poly(L-glutamic acid) (PGA)-(Gd-DO3A) conjugate with a biodegradable cystamine spacer was prepared and evaluated for in vivo detection of an angiogenesis biomarker, alpha(v)beta3 integrin, in neoplastic tissues with T1 mapping, a quantitative magnetic resonance imaging (MRI) technique. The binding activity of the c(RGDfK) containing conjugate was investigated using in vitro vitronectin assay with human prostate carcinoma DU145 cell line and Kaposi's sarcoma SLK cell line. The peptide c(RGDfK) and PGA-cystamine-(Gd-DO3A) conjugate were used as controls. The binding affinity of polymer bound c(RGDfK) was slightly lower than free c(RGDfK) peptide. The RGD targeted conjugate had higher binding affinity to the DU145 cells than the SLK cells, which was consistent to free c(RGDfK). The imaging of alpha(v)beta3 integrin with targeted PGA-cystamine-(Gd-DO3A) was evaluated in nude mice bearing DU145 and SLK xenografts at a dose of 5 micromol-Gd/kg. The targeted conjugate demonstrated higher in vivo binding affinity to the DU145 xenografts than the SLK xenografts, resulting in a significant decrease of T1 values of water protons in the periphery of the DU145 tumors as shown in the MR T1 maps. No significant decrease of T1 values was observed in the SLK tumor with the targeted conjugate and in both tumors with the non-targeted conjugate. The targeted polymeric Gd(III) chelate conjugate with a degradable spacer has the potential to be a new paradigm for safe and effective probes in molecular imaging with quantitative MR T1 mapping.     

A computational proposal for designing structured RNA pools for in vitro selection of RNAs

Although in vitro selection technology is a versatile experimental tool for discovering novel synthetic RNA molecules, finding complex RNA molecules is difficult because most RNAs identified from random sequence pools are simple motifs, consistent with recent computational analysis of such sequence pools. Thus, enriching in vitro selection pools with complex structures could increase the probability of discovering novel RNAs. Here we develop an approach for engineering sequence pools that links RNA sequence space regions with corresponding structural distributions via a "mixing matrix" approach combined with a graph theory analysis. We define five classes of mixing matrices motivated by covariance mutations in RNA; these constructs define nucleotide transition rates and are applied to chosen starting sequences to yield specific nonrandom pools. We examine the coverage of sequence space as a function of the mixing matrix and starting sequence via clustering analysis. We show that, in contrast to random sequences, which are associated only with a local region of sequence space, our designed pools, including a structured pool for GTP aptamers, can target specific motifs. It follows that experimental synthesis of designed pools can benefit from using optimized starting sequences, mixing matrices, and pool fractions associated with each of our constructed pools as a guide. Automation of our approach could provide practical tools for pool design applications for in vitro selection of RNAs and related problems.     

RagPools: RNA-As-Graph-Pools--a web server for assisting the design of structured RNA pools for in vitro selection

SUMMARY: Our RNA-As-Graph-Pools (RagPools) web server offers a theoretical companion tool for RNA in vitro selection and related problems. Specifically, it suggests how to construct RNA sequence/structure pools with user-specified properties and assists in analyzing resulting distributions. This utility follows our recently developed approach for engineering sequence pools that links RNA sequence space regions with corresponding structural distributions via a 'mixing matrix' approach combined with a graph theory analysis of RNA secondary-structure space; the mixing matrix specifies nucleotide transition rates, and graph theory links sequences to simple graphical objects representing RNA motifs. The companion RagPools web server ('Designer' component) provides optimized starting sequences, mixing matrices and associated weights in response to a user-specified target pool structure distribution. In addition, RagPools ('Analyzer' component) analyzes the motif distribution of pools generated from user-specified starting sequences and mixing matrices. Thus, RagPools serves as a guide to researchers who aim to synthesize RNA pools with desired properties and/or experiment in silico with various designs by our approach. AVAILABILITY: The web server is accessible on the web at http://rubin2.biomath.nyu.edu     

Enantiomeric separation of imidazolinone herbicides using chiral high-performance liquid chromatography

Chiral high-performance liquid chromatography (HPLC) is one of the most powerful tools to prepare enantiopure standards of chiral compounds. In this study, the enantiomeric separation of imidazolinone herbicides, i.e., imazethapyr, imazapyr, and imazaquin, was investigated using chiral HPLC. The enantioselectivity of Chiralpak AS, Chiralpak AD, Chiralcel OD, and Chiralcel OJ columns for the three analytes was compared under similar chromatographic conditions. Chiralcel OJ column showed the best chiral resolving capacity among the test columns. The resolved enantiomers were distinguished by their signs of circular dichroism detected at 275 nm and their structures confirmed with LC-mass spectrometric analysis. Factors affecting the chiral separation of imidazolinones on Chiralcel OJ column were characterized. Ethanol acted as a better polar modifier than the other alcohols including 2-propanol, 1-butanol, and 1-pentanol. Although the acidic modifier in the mobile phase did not influence chiral recognition, it was necessary for reducing the retention time of enantiomers and suppressing their peak tailing. Thermodynamic evaluation suggests that enantiomeric separation of imidazolinones on Chiralcel OJ column is an enthalpy-driven process from 10 to 40 degrees C. This study also shows that small amounts of pure enantiomers of imidazolinones may be obtained by using the analytical chiral HPLC approach.     

Crystal structure of the Leishmania major phosphodiesterase LmjPDEB1 and insight into the design of the parasite-selective inhibitors

Human leishmaniasis is a major public health problem in many countries, but chemotherapy is in an unsatisfactory state. Leishmania major phosphodiesterases (LmjPDEs) have been shown to play important roles in cell proliferation and apoptosis of the parasite. Thus LmjPDE inhibitors may potentially represent a novel class of drugs for the treatment of leishmaniasis. Reported here are the kinetic characterization of the LmjPDEB1 catalytic domain and its crystal structure as a complex with 3-isobutyl-1-methylxanthine (IBMX) at 1.55 A resolution. The structure of LmjPDEB1 is similar to that of human PDEs. IBMX stacks against the conserved phenylalanine and forms a hydrogen bond with the invariant glutamine, in a pattern common to most inhibitors bound to human PDEs. However, an extensive structural comparison reveals subtle, but significant differences between the active sites of LmjPDEB1 and human PDEs. In addition, a pocket next to the inhibitor binding site is found to be unique to LmjPDEB1. This pocket is isolated by two gating residues in human PDE families, but constitutes a natural expansion of the inhibitor binding pocket in LmjPDEB1. The structure particularity might be useful for the development of parasite-selective inhibitors for the treatment of leishmaniasis.