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961.
962.
Davide Antoniani Paola Bocci Anna Maciąg Nadia Raffaelli Paolo Landini 《Applied microbiology and biotechnology》2010,85(4):1095-1104
In Gram-negative bacteria, production of bis-(3′,5′)-cyclic diguanylic acid (c-di-GMP) by diguanylate cyclases (DGCs) is the
main trigger for production of extracellular polysaccharides and for biofilm formation. Mutants affected in c-di-GMP biosynthesis
are impaired in biofilm formation, thus making DGCs interesting targets for new antimicrobial agents with anti-biofilm activity.
In this report, we describe a strategy for the screening for DGC inhibitors consisting of a combination of three microbiological
assays. The primary assay utilizes an Escherichia coli strain overexpressing the adrA gene, encoding the DGC protein AdrA, and relies on detection of AdrA-dependent cellulose production as red colony phenotype
on solid medium supplemented with the dye Congo red (CR). Presence of DGC inhibitors blocking AdrA activity would result in
a white phenotype on CR medium. The CR assay can be performed in 96-well microtiter plates, making it suitable for high-throughput
screenings. To confirm specific inhibition of c-di-GMP biosynthesis, chemical compounds positive in the CR assay are tested
for their ability to inhibit biofilm formation and in a reporter gene assay which monitors expression of curli-encoding genes
as a function of DGC activity. Screening of a chemical library using the described approach allowed us to identify sulfathiazole,
an antimetabolite drug, as an inhibitor of c-di-GMP biosynthesis. Sulfathiazole probably affects c-di-GMP biosynthesis in
an indirect fashion rather than by binding to DGCs; however, sulfathiazole represents the first example of drug able to affect
biofilm formation by interfering with c-di-GMP metabolism. 相似文献
963.
Silvia Rocchiccioli Lorenzo Citti Claudia Boccardi Nadia Ucciferri Lorena Tedeschi Caterina Lande Maria Giovanna Trivella Antonella Cecchettini 《Proteome science》2010,8(1):15
Background
The use of chromatography coupled with mass spectrometry (MS) analysis is a powerful approach to identify proteins, owing to its capacity to fractionate molecules according to different chemical features. The first protein expression map of vascular smooth muscle cells (VSMC) was published in 2001 and since then other papers have been produced. The most detailed two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) map was presented by Mayr et al who identified 235 proteins, corresponding to the 154 most abundant unique proteins in mouse aortic VSMC. A chromatographic approach aimed at fractionating the VSMC proteome has never been used before. 相似文献964.
In the present study, we purified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) which is involved in cellular energy production and has important housekeeping functions, from the ciliate Tetrahymena thermophila using a three-step procedure. The enzyme was purified ~68 folds by ammonium sulfate precipitation, followed by two steps of column chromatography (DEAE-cellulose and Mono-S). The purified enzyme is a homotetramer with a molecular weight of ~120 kDa. Isoelectric focusing analysis showed the presence of only one basic GAPDH isoform with an isoelectric point of 8.8. Western blot analysis showed a single 32-kDa band corresponding to the enzyme subunit using a monospecific polyclonal antibody against the T. thermophila GAPDH. The maximum of enzyme activity occurred at pH 8.0 and at 30-35°C. The apparent K(m) values for both NAD(+) and D-glyceraldehyde-3-phosphate were 0.102 ± 0.012 and 0.360 ± 0.018 mM, respectively. The maximal velocity (V(max)) was 39.40 ± 2.95 U/mg. The T. thermophila GAPDH is inhibited by oxidative and nitrosative stress reagents. 相似文献
965.
966.
Nesrine Zahed Karim Hosni Nadia Ben Brahim Monem Kallel Houcine Sebei 《Acta Physiologiae Plantarum》2010,32(6):1221-1227
Gas chromatography-flame ionisation detection (GC-FID) and gas chromatography–mass spectrometry (GC–MS) analyses of the essential
oils of leaves and fruits of the ornamental Shinus molle L. were reported and their allelopathic effect on wheat (Triticum aestivum L.) was evaluated. Qualitative and quantitative differences between fruit and leaf oils were observed. Both oils were rich
in monoterpene hydrocarbons and the major constituents were limonene and β-phellendrene (35.9–65.4%), α-phellendrene (24.3–20.1%),
myrcene (12.8–7.7%) and α-pinene (5.9–1.7%) for fruits and leaves, respectively. Both essential oils showed a dose-dependent
allelopathic activity on wheat germination and radicle elongation with leaf oil being the more phytotoxic. 相似文献
967.
Shoukri MM Donner A Dessouky NA Subhani S Al-Joufan M Al-Omrani A Al-Mohanna F Al Halees ZY 《The international journal of biostatistics》2010,6(1):Article 3
Family studies are widely used for research into genetic and environmental influences on human traits. In this paper, we establish statistical methodology for the estimation of a new measure of sib similarity with respect to dichotomous traits measured on each member of within family sib-pair. We call this parameter "excess risk." For inference problems involving a single sample, we construct a large sample confidence interval on the concerned parameter. It has long been suspected that consanguinity is a risk factor for many genetic defects. Therefore, we establish a procedure to test the significance of the difference between excess risk parameters in a sample of consanguineous marriages and another sample of non-consanguineous marriages. We apply the methodology to data from a hospital-based congenital heart defects registry in Saudi Arabia, a population in which consanguinity is quite common. 相似文献
968.
Somatic and motor components of action simulation 总被引:1,自引:0,他引:1
Seminal studies in monkeys report that the viewing of actions performed by other individuals activates frontal and parietal cortical areas typically involved in action planning and execution. That mirroring actions might rely on both motor and somatosensory components is suggested by reports that action observation and execution increase neural activity in motor and in somatosensory areas. This occurs not only during observation of naturalistic movements but also during the viewing of biomechanically impossible movements that tap the afferent component of action, possibly by eliciting strong somatic feelings in the onlooker. Although somatosensory feedback is inherently linked to action execution, information on the possible causative role of frontal and parietal cortices in simulating motor and sensory action components is lacking. By combining low-frequency repetitive and single-pulse transcranial magnetic stimulation, we found that virtual lesions of ventral premotor cortex (vPMc) and primary somatosensory cortex (S1) suppressed mirror motor facilitation contingent upon observation of possible and impossible movements, respectively. In contrast, virtual lesions of primary motor cortex did not influence mirror motor facilitation. The reported double dissociation suggests that vPMc and S1 play an active, differential role in simulating efferent and afferent components of observed actions. 相似文献
969.
Nadia G Elhefnawy 《Diagnostic pathology》2011,6(1):1-3
Background
Special stains, such as reticulin stain and CD34 immunostain, are very helpful in the diagnosis of well differentiated hepatocellular carcinoma (HCC). Most studies have shown that absent or decreased reticulin stain or an abnormal reticulin pattern with widened trabeculae is reliable for the diagnosis of well-differentiated HCC.Case report
We report here two cases of well differentiated HCC with an unusual reticulin staining pattern. A strongly positive reticulin network was preserved within the tumor, which surrounded individual tumor cells in a monolayered trabecular pattern. At the same time, an increased CD34 stain was present in the tumor.Conclusions
This unusual reticulin pattern represents part of the diverse reticulin staining patterns seen in HCC. Although this staining pattern is rare, it should be recognized when diagnosing well-differentiated HCC in small samples such as cellblock of fine needle aspiration or small core biopsies. 相似文献970.