High Throughput Screen Identifies Small Molecule Inhibitors Specific for Mycobacterium tuberculosis Phosphoserine Phosphatase

The emergence of drug-resistant strains of Mycobacterium tuberculosis makes identification and validation of newer drug targets a global priority. Phosphoserine phosphatase (PSP), a key essential metabolic enzyme involved in conversion of O-phospho-l-serine to l-serine, was characterized in this study. The M. tuberculosis genome harbors all enzymes involved in l-serine biosynthesis including two PSP homologs: Rv0505c (SerB1) and Rv3042c (SerB2). In the present study, we have biochemically characterized SerB2 enzyme and developed malachite green-based high throughput assay system to identify SerB2 inhibitors. We have identified 10 compounds that were structurally different from known PSP inhibitors, and few of these scaffolds were highly specific in their ability to inhibit SerB2 enzyme, were noncytotoxic against mammalian cell lines, and inhibited M. tuberculosis growth in vitro. Surface plasmon resonance experiments demonstrated the relative binding for these inhibitors. The two best hits identified in our screen, clorobiocin and rosaniline, were bactericidal in activity and killed intracellular bacteria in a dose-dependent manner. We have also identified amino acid residues critical for these SerB2-small molecule interactions. This is the first study where we validate that M. tuberculosis SerB2 is a druggable and suitable target to pursue for further high throughput assay system screening.     

培菲康联合乳杆菌治疗老年细菌性阴道病

目的 观察口服培菲康联合阴道用乳杆菌治疗老年细菌性阴道病的疗效。方法 选取2016年1月至2017年8月我院就诊的114例老年细菌性阴道病患者,随机分为联合治疗组、乳杆菌组和对照组各38例,联合治疗组给予口服培菲康联合阴道用乳杆菌活菌胶囊,乳杆菌组给予阴道用乳杆菌活菌胶囊,对照组给予阴道用甲硝唑栓。观察三组患者治疗效果、复发情况以及阴道pH的变化。结果 联合治疗组和乳杆菌组的治疗总有效率均明显高于对照组(χ2=4.290 3、4.069 9,均P<0.05),联合治疗组治疗有效的患者3、6个月内复发率均明显低于对照组(χ2=5.526 0、6.983 7,均P<0.05),联合治疗组治疗有效的患者6个月内复发率明显低于乳杆菌组(χ2=5.499 4,P<0.05),治疗6个月后联合治疗组阴道pH值明显低于乳杆菌组和对照组(t=3.736 1、4.353 8,均P<0.05)。结论 口服培菲康联合阴道用乳杆菌治疗老年细菌性阴道病,不仅能提高近期疗效,对于长期预防也有明显的效果。     

Light and electron microscopic study of the bacterial adhesion to termite flagellates applying lectin cytochemistry

Summary Many of the flagellates inhabiting the hindgut of lower termites are associated with ectobiotic, rod-like bacteria or spirochetes. Different types of attachment sites are present. Electron dense material underlies, e.g., the plasma membrane ofJoenia annectens at the contact site, whereas other attachment sites do not show any visible specializations. The host cell's glycocalyx may, however, be reduced at the attachment sites as it is the case inDevescovina glabra. The thick glycocalyx ofStephanonympha nelumbium is not changed at the sites where bacterial rods attach, but spirochetes penetrate to a certain extent. Bacteria which colonize the extracellular surface structures ofMicrorhopalodina multinucleata express their own glycocalyx to mediate a contact. In this study we focussed on the examination of one common mode of interaction between bacteria and their host cells, i.e., adhesion via lectins and sugars. The sugar composition was analysed by light and electron microscopic labelling experiments using the lectins Con A, WGA and SBA. In general, only the posterior body surface ofJoenia which is colonized with bacteria is labelled. The demonstrated sugars are found in fibrous glycocalyx portions surrounding the attachment sites of the bacteria. Such glycocalyx fibres in combination with the electron dense material supporting the attachment sites seem to be the prerequisites for bacterial attachment. InD. glabra, however, a role for sugars in mediating the attachment could not be demonstrated. Removal of the ectobiotes using antibiotics revealed that the specialized contact sites ofJoenia are present in the absence of bacteria and thus possibly serve to attract bacteria. Nothing, however, remains of the former attachment sites in bacteria-freeDevescovina cells. Attachment sites in this case could be induced by bacterial contact. There is not one general mechanism for bacterial attachment to termite flagellates; rather, adhesion seems to follow different strategies.Abbreviations Con A concanavalin A - DAB 3,3-diaminobenzidine tetrahydrochloride - DAPI 4,6-diamidino-2-phenylindole - DIC differential interference contrast - FA formaldehyde - FITC fluorescein isothiocyanate - GA glutaraldehyde - PB Soerensen's phosphate buffer - PC phase contrast - pen/strep penicillin and streptomycin - SBA soybean agglutinin - SEM scanning electron microscope - TBS Tris buffer saline - TEM transmission electron microscope - WGA wheat germ agglutinin Dedicated to Prof. Dr. Dr. h.c. Eberhard Schnepf on the occasion of his retirement     

抗感青枯病番茄的内生细菌数量动态分析及其对青枯病的生物防治

对番茄内生细菌数量动态及其对青枯病的生物防治研究结果表明:番茄内生细菌可来源于种子内部。番茄不同生育期,内生细菌数量最多在成株期,其中抗病品种根、茎分别为24.3×104CFU/g鲜重和22.9×104CFU/g鲜重,感病品种根、茎分别为9.8×104CFU/g鲜重和13.4×104CFU/g鲜重。抗病品种中具有拮抗青枯菌的内生细菌菌株为17个,感病品种中7个。部分内生细菌具促进番茄种子萌发和防治番茄青枯病的作用,其中5R和3R内生菌株的防病效果分别达91.7%和81.3%。     

S100A14在乳腺癌不同分子亚型中表达的临床病理研究

目的:探讨S100钙结合蛋白A14(S100A14)在乳腺癌不同分子亚型中的表达及临床病理意义,为确定新的分子分型标志物提供参考依据。方法:254例乳腺癌石蜡组织来源于2013年1月16日至2014年5月22日在中南大学湘雅医学院附属肿瘤医院暨湖南省肿瘤医院进行乳腺癌根治术的患者。应用免疫组织化学方法检测S100A14在乳腺癌组织中的表达,分析其S100A14在不同分子亚型乳腺癌组织中表达及其与患者临床病理指标间的相关性,采用Kaplan-Meier法分析S100A14蛋白表达与乳腺癌患者预后的关系。结果:S100A14在ER+/PR+/HER2+型、ER+/PR+/HER2-型、ER-/PR-/HER2+型、ER-/PR-/HER2-型乳腺癌四种分子亚型中的阳性表达分别为38.5%、47.1%、75.5%、80.0%,以在ER-/PR-/HER2-型中表达最高,在ER+/PR+/HER2+型中表达最低,四组间的阳性表达比较差异有显著统计学意义(P0.01);S100A14的表达与乳腺癌患者术后肝转移呈正相关(r=0.134,P0.05),与ER、PR表达均呈负相关(r=-0.353,P0.01),而与ER+/PR+/HER2+型、ER+/PR+/HER2-型乳腺癌的临床病理特征无显著相关性(P0.05)。在ER-/PR-/HER2+型乳腺癌中,有腋窝淋巴结转移组患者的S100A14阳性表达率明显高于无腋窝淋巴结转移组,差异有统计学意义(P0.05);在ER-/PR-/HER2-型中,S100A14表达与术后肺转移呈负相关(r=-0.272, P=0.044)。结论:S100A14在不同分子亚型乳腺癌中表达存在差异,其表达与不同分子类型乳腺癌转移或复发有关,可能作为乳腺癌分子分型的候选标记物。     

Structure of the O-polysaccharide of a serologically separate strain of Proteus mirabilis, TG 332, from a new proposed Proteus serogroup O50

The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Proteus mirabilis TG 332 strain. The following structure of the O-polysaccharide was determined by chemical methods along with NMR spectroscopy, including 2D COSY, TOCSY, ROESY and 1H, 13C HMQC experiments: [see equation in text]. The O-polysaccharide studied has a unique structure among Proteus O-antigens. Accordingly, P. mirabilis TG 332 is serologically separate, and we propose to classify this strain into a new Proteus serogroup, O50. The nature of minor epitopes that provide a cross-reactivity of P. mirabilis TG 332 O-antiserum with the LPS of P. mirabilis O30 and Proteus penneri 34 (O60) is discussed.     

Effect of light internsity on vesicle formation in Chlorobium

1. Chlorobium limicola forma sp. thiosulfatophilum was cultivated at 22 and 22000 lux. 2. The content of bchl d on a protein basis in the low light intensity cultures was about twice that of the high light intensity cultures. 3. After growth at 22 lux the red bchl d peak was at c. 743 nm, while at the higher intensity this peak was at c. 732 nm. 4. Electron microscopy of thin sections of Chlorobium revealed that vesicle size was greater at the low light intensity than at the high. 5. This was confirmed by sucrose density gradient centrifugation of differentially ¹⁴C-labelled vesicles from cultures grown at the two intensities. 6. The optimum temperature for growth was about 35°C. Incubation at the optimum temperature was particularly beneficial at high light intensity.Abbreviation bchl bacteriochlorophyll     

Structure-function studies of the Vitreoscilla hemoglobin D-region

The D-region connecting helices C and E of Vitreoscilla hemoglobin (VHb) appears disordered in the crystal structure. Six site-directed mutants in this region were made to investigate its possible functions. The mutant VHb's were analyzed using UV-visible and FTIR spectroscopy, using primarily the CO liganded forms, and their heme/protein ratios were determined. The results implicate Asp44, Arg47, and Glu49 as especially important in heme-globin interactions and ligand binding, and enabled construction of a model in which the D-region forms a loop that protrudes upward over the heme. Interactions between VHb (wild type and the D-region mutants) with the flavin domain of 2,4-DNT dioxygenase from Burkholderia were tested using bacterial two-hybrid screening. There was a correlation between the extent of the D-loop perturbation predicted for each mutant and the amount of the reduction in VHb-flavin domain interaction, suggesting that this region may be more generally involved in binding of VHb to flavoproteins.     

Physicochemical properties of bacterial glycopolymers in relation to bioactivity

An overview is given on the physicochemical properties of bacterial glycopolymers, i.e., pure oligo- and polysaccharides as well as glycolipids. Data from analysis of the chemical and physicochemical properties of various sugar polymers are summarized. Furthermore, data are presented on the thorough characterization of the most important class of bacterial glycopolymers, the lipopolysaccharides (LPS). These data comprise the chemical characterization, the gel to liquid crystalline phase transition behaviour of their acyl chains, the ultrastructural studies of their morphology, and the investigation of the types of aggregate structures present above the critical micellar concentration (CMC). Furthermore, the relevance of these data with respect to an understanding of the various biological effects elicited by LPS is discussed.     

Multilocus sequence typing (MLST) of Escherichia coli O78 strains

Strains of Escherichia coli serotype O78 are associated with many diseases, including invasive infections, in humans and farm animals. The clonal relationship between strains from different hosts is therefore important for assessing the risk of zoonotic infections. Here we propose a multilocus sequence typing scheme for E. coli, based on six housekeeping genes. Preliminary, but significant, results indicate that clonal division in E. coli O78 strains is host independent, and closely related clones reside in different hosts. There was a positive correlation between virulence and clonal origin.