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排序方式: 共有136条查询结果,搜索用时 187 毫秒
91.
AE Clarke S Bernatsky KH Costenbader MB Urowitz DD Gladman PR Fortin M Petri S Manzi DA Isenberg A Rahman D Wallace C Gordon C Peschken MA Dooley EM Ginzler C Aranow SM Edworthy O Nived S Jacobsen G Ruiz-Irastorza E Yelin SG Barr L Criswell G Sturfelt L Dreyer I Blanco L Gottesman CH Feldman R Ramsey-Goldman 《Arthritis research & therapy》2012,14(Z3):A16
92.
Eliana Alves Liliana Costa Carla MB Carvalho Jo?o PC Tomé Maria A Faustino Maria GPMS Neves Augusto C Tomé José AS Cavaleiro ?ngela Cunha Adelaide Almeida 《BMC microbiology》2009,9(1):70
Background
In recent times photodynamic antimicrobial therapy has been used to efficiently destroy Gram (+) and Gram (-) bacteria using cationic porphyrins as photosensitizers. There is an increasing interest in this approach, namely in the search of photosensitizers with adequate structural features for an efficient photoinactivation process. In this study we propose to compare the efficiency of seven cationic porphyrins differing in meso-substituent groups, charge number and charge distribution, on the photodynamic inactivation of a Gram (+) bacterium (Enterococcus faecalis) and of a Gram (-) bacterium (Escherichia coli). The present study complements our previous work on the search for photosensitizers that might be considered good candidates for the photoinactivation of a large spectrum of environmental microorganisms. 相似文献93.
Background
All eukaryotes with the exception of plants use an actomyosin ring to generate a constriction force at the site of cell division (cleavage furrow) during mitosis and meiosis. The structure and filament forming abilities located in the C-terminal or tail region of one of the main components, myosin II, are important for localising the molecule to the contractile ring (CR) during cytokinesis. However, it remains poorly understood how myosin II is recruited to the site of cell division and how this recruitment relates to myosin filament assembly. Significant conservation between species of the components involved in cytokinesis, including those of the CR, allows the use of easily genetically manipulated organisms, such as budding yeast (Saccharomyces cerevisiae), in the study of cytokinesis. Budding yeast has a single myosin II protein, named Myo1. Unlike most other class II myosins, the tail of Myo1 has an irregular coiled coil. In this report we use molecular genetics, biochemistry and live cell imaging to characterize the minimum localisation domain (MLD) of budding yeast Myo1. 相似文献94.
Ryanodine receptor (RyR)-gated Ca2+ stores have recently been identified in cochlear spiral ganglion neurons (SGN) and likely contribute to Ca2+ signalling associated with auditory neurotransmission. Here, we identify an ionotropic glutamate receptor signal transduction pathway which invokes RyR-gated Ca2+ stores in SGN via Ca2+-induced Ca2+ release (CICR). Ca2+ levels were recorded in SGN in situ within rat cochlear slices (postnatal day 0-17) using the Ca2+ indicator fluo-4. RyR-gated Ca2+ stores were confirmed by caffeine-induced increases in intracellular Ca2+ which were blocked by ryanodine (100 microM) and were independent of external Ca2+. Glutamate evoked comparable increases in intracellular Ca2+, but required the presence of external Ca2+. Ca2+ influx via the glutamate receptor was found to elicit CICR via RyR-gated Ca2+ stores, as shown by the inhibition of the response by prior depletion of the Ca2+ stores with caffeine, the SERCA inhibitor thapsigargin, or ryanodine. The glutamate analogue AMPA (alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid) elicited Ca2+ responses that could be inhibited by caffeine. Glutamate- and AMPA-mediated Ca2+ responses were eliminated with the AMPA/Kainate receptor antagonist DNQX (6,7-dinitroquinoxaline-2,3-dione). These data demonstrate functional coupling between somatic AMPA-type glutamate receptors and intracellular Ca(2+) stores via RyR-dependent CICR in primary auditory neurons. 相似文献
95.
Kathleen?MB?Vinette Kathleen?M?Gibney Roy?Proujansky Paul?T?FawcettEmail author 《BMC microbiology》2004,4(1):5
Background
Histology and/or culture are generally considered the gold standard for the detection of H. pylori infection. Especially in children, these tests may result in a false negative outcome because of patchy distribution of the organism in the stomach mucosa. We have developed a PCR assay utilizing nested primer pairs directed against a subunit of the H. pylori urease gene (ureA). As part of a prospective evaluation of diagnostic tests to aid in detecting H. pylori infection in children, the aim of this study was to compare our PCR and Western blot assays with results obtained from histologic examination of biopsy specimens, rapid urease tests, and an FDA approved serologic assay and published PCR results to determine if we could validate the assays for diagnostic use on our patient population.Results
Gastric biopsy specimens obtained from 101 pediatric patients were evaluated for the presence of H. pylori using histologic techniques, rapid urease (CLOtest) test and the PCR assay. Serum samples from each patient were assayed using both ELISA and Western Blot for antibodies to H. pylori. A total of 32 patients tested were positive by at least one of the methods evaluated. Thirteen patients had positive histology, 13 had a positive CLOtest, and 17 patients had positive H. pylori PCR. Out of the 13 CLO positive patients, 12 were positive by histologic analysis and all 13 were positive by PCR. Results of serologic tests on the same population did not correlate well with other assays. Twenty-eight patients showed serologic evidence of H. pylori infection, of which 9 were both CLO and histology positive and 12 were positive by PCR. Of the seropositive patients, 26 were ELISA positive, 13 were positive by Western blot, and 11 by both serologic methods.Conclusions
The results obtained suggest that our nested PCR assay has the specificity and sensitivity necessary for clinical application when compared to standard histologic examination and rapid urease test. In addition, we found the current commercially available approved ELISA method appears unable to accurately detect H. pylori in this population. The Western blot assay yielded better concordance with CLOtest and histology, but not as good as the nested PCR assay.96.
Using a combination of experimental and numerical approaches, we have tested two different approaches to calculating the sarcoplasmic reticulum (SR) Ca2+ release flux, which gives rise to cardiac muscle Ca2+ sparks. By using two-photon excited spot photolysis of DM-Nitrophen, known Ca2+ release flux time courses were generated to provide the first experimental validation of spark flux reconstruction algorithms. These artificial Ca2+ sparks show that it is possible to calculate the SR Ca2+ release waveform with reasonable accuracy, provided the flux equations reasonably reflect the properties of the experimental system. Within cardiac muscle cells, we show that Ca2+ flux reconstruction is complicated by the substantial dye binding to proteins, a factor that has not been adequately addressed in previous flux reconstruction algorithms. Furthermore, our numerical experiments suggest that the calculated time course of release flux inactivation based on conventional flux reconstruction algorithms is likely to be in error. We therefore developed novel algorithms based on an explicit dye binding scheme. When these algorithm were applied to evoked Ca2+ sparks in rat cardiac ventricular myocytes, the reconstructed Ca2+ release waveform peaked in ~5 ms and decayed with a halftime of approximately 5 ms. The peak flux magnitude was 7-12 pA, suggesting that sparks must arise from clusters of >15 ryanodine receptors. 相似文献
97.
W. J. Lederer M. B. Cannell N. M. Cohen J. R. Berlin 《Molecular and cellular biochemistry》1989,89(2):115-119
We have investigated the links between electrical excitation and contraction in mammalian heart muscle. Using isolated single cells from adult rat ventricle, a whole-cell voltage-clamp technique and quantitative fluorescence microscopy, we have measured simultaneously calcium current (Ica) and [Ca2+]i (with fura-2). We find that the voltage-dependence of Ica and the [Ca 2+]i-transient and the dependence of [Ca2+]i-transient on depolarization-duration cannot both be readily explained by a simple calcium-induced Ca-release (CICR) mechanism. Additionally, we find that when [Ca2+]i and [Na+]i are at their diastolic levels, activation of the Na-Ca exchange mechanism by depolarization does not measurably trigger the release of Ca2+i. Finally, measuring Ica in adult and neonatal rat heart cells and using the alkaloid ryanodine, we have carried out complementary experiments. These experiments show that there may be an action of ryanodine on Ica that is independent of [Ca2+]i and independent of a direct action of the alkaloid on the calcium channel itself. Along with experiments of others showing that ryanodine binds to the sarcoplasmic reticulum calcium-release channel/spanning protein complex, our data suggests a model to explain our findings. The model links the calcium channels responsible for Ica to the sarcoplasmic reticulum by means of one or more of the spanning protein(s). Information from the calcium channel can be communitated to the sarcoplasmic reticulum by this route and, presumably, information can move in the opposite direction from the sarcoplasmic reticulum to the calcium channel. 相似文献
98.
R. Q. Cannell R. K. Belford P. S. Blackwell G. Govi R. J. Thomson 《Plant and Soil》1985,85(3):361-373
Summary Winter oats were grown outdoors in lysimeters containing monoliths of a sandy loam soil. The soil was either freely-drained throughout the experiment or waterlogged to the soil surface from mid-January until mid-April. After the start of waterlogging the oxygen flux density decreased most rapidly nearer the soil surface and in the upper 50 cm declined to zero. At 80 cm depth the oxygen flux density at the end of the waterlogging still had not diminished to zero. While the soil was waterlogged root growth was negligible in the 20–50 cm zone of the soil profile, whereas below that depth root growth continued, reaching 95 cm by the end of the treatment. During the latter part of the waterlogging period root growth resumed in the upper 10 cm, and in the upper 2.5 cm was greater than in the freelydrained treatment.At the end of the waterlogging period, the total root length and shoot dry weights were 77 and 60% of those in the freely-drained treatment, tillering was restricted and leaf area index diminished. However, by anthesis, root length and shoot weights of the plants that had been waterlogged were only 10 and 12% less respectively than for the freely-drained plants. At harvest, total dry matter and grain yields were only 9% less, the latter largely through fewer grains per panicle. 相似文献
99.
Concepción Avila Antonio J. Márquez Purificación Pajuelo Martin E. Cannell Roger M. Wallsgrove Brian G. Forde 《Planta》1993,189(4):475-483
The NH2-terminal sequences of ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) purified from barley (Hordeum vulgare L.) and Chlamydomonas reinhardtii (Dangeard), and of a barley peptide, were determined and the barley sequences were used to design oligonucleotide primers for the polymerase chain reaction. A specific 1.3-kilobase (kb) cDNA fragment specifying the NH2-terminal one-third of the mature barley polypeptide, was amplified, cloned and sequenced. The NH2-terminus of plant Fd-GOGAT is highly conserved and homologous to the NH2-terminus of the heavy subunit of Escherichia coli NADPH-GOGAT. Based on sequence homologies, we tentatively identified the NH2-terminal region of Fd-GOGAT as the glutamine-amidotransferase domain, which is related to the corresponding domain of the purF-type amidotransferases. The Fd-GOGAT cDNA clone, and polyclonal antibodies raised against the barley enzyme, were used to analyse four Fd-GOGAT-deficient photorespiratory mutants. Three mutants (RPr 82/1, RPr 82/9 and RPr 84/82) had no detectable Fd-GOGAT protein in leaves, while the fourth (RPr 84/42) had a small amount of cross-reacting material. Hybridization to Northern blots of total leaf RNA revealed that both RPr 82/9 and RPr 84/82 were indistinguishable from the parental line (Maris Mink), having normal amounts of a 5.7-kb mRNA species. On the other hand, RPr 82/2 and RPr 84/42 each contained two distinct hybridizing RNA species, one of which was larger than 5.7 kb, the other smaller. Using a set of wheat-barley telosomic addition lines we have assigned the Fd-GOGAT structural locus to the short arm of chromosome 2.Abbreviations bp
kbase pairs
- cDNA
copy DNA
- Fd
ferredoxin
- GOGAT
glutamate synthase
- GAT
glutamine amidotransferase
- kb
kilobase
- PCR
polymerase chain reaction
C.A. was the holder of a Fleming award from the British Council and the Spanish Ministry of Education and Science. A.J.M. was for part of the work the recipient of a European Molecular Biology Organization postdoctoral fellowship. The research was also partly supported by contract no. BAP/O354/E of the Biotechnology Action Programme of the E.C., by an Acciones Integradas award (no. 40/125) from the British Council and the Spanish Ministry of Education and Science, by the Junta de Andalucia (to Group 3263) and by project PB91-0613 from DGICYT (Spain). We thank Daryl Pappin (Department of Biochemistry, University of Leeds) for amino-acid sequencing, and Martin Cornelius (Rothamsted Experimental Station, Harpenden, Herts., UK) for synthesis of oligonuleotides. 相似文献
100.