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51.
Matthew-Wood syndrome is caused by truncating mutations in the retinol-binding protein receptor gene STRA6 总被引:3,自引:0,他引:3 下载免费PDF全文
52.
Lozo J Jovcic B Kojic M Dalgalarrondo M Chobert JM Haertlé T Topisirovic L 《Current microbiology》2007,55(3):266-271
Screening the collection of natural isolates from semi-hard homemade cheese resulted in isolation and characterization of
strain Lactobacillus paracasei subsp. paracasei BGSJ2-8. The strain BGSJ2-8 harbors several important phenotypes, such as bacteriocin production, aggregation phenomenon,
and production of proteinase. Bacteriocin SJ was purified by three-step chromatography. Mass spectrometry established molecular
mass of the active peptide at 5372 Da. The auto-aggregation phenotype of wild-type (WT) strain was mediated by secreted aggregation-promoting
factor (protein of molecular mass > 200 kDa), probably acting in cooperation with other cell surface protein(s). Comparative
study of WT and its spontaneous nonaggregating derivative revealed that aggregation factor was responsible for the observed
differences in the bacteriocin and proteinase activities. Bacteriocin SJ activity and resistance to different stresses were
higher in the presence of aggregating factor. In contrast, proteinase activity was stronger in the nonaggregating derivative. 相似文献
53.
Fluorescent fructose derivatives for imaging breast cancer cells 总被引:1,自引:0,他引:1
Levi J Cheng Z Gheysens O Patel M Chan CT Wang Y Namavari M Gambhir SS 《Bioconjugate chemistry》2007,18(3):628-634
Breast cancer cells are known to overexpress Glut5, a sugar transporter responsible for the transfer of fructose across the cell membrane. Since Glut5 transporter is not significantly expressed in normal breast cells, fructose uptake can potentially be used to differentiate between normal and cancerous cells. Fructose was labeled with two fluorophores at the C-1 position: 7-nitro-1,2,3-benzadiazole (NBD) and Cy5.5. The labeling site was chosen on the basis of the presence and substrate specificity of the key proteins involved in the first steps of fructose metabolism. Using fluorescence microscopy, the uptake of the probes was studied in three breast cancer cell lines: MCF 7, MDA-MB-435, and MDA-MB-231. Both fluorescent fructose derivatives showed a very good uptake in all tested cell lines. The level of uptake was comparable to that of the corresponding glucose analogs, 2-NBDG and Cy5.5-DG. Significant uptake of 1-NBDF derivative was not observed in cells lacking Glut5 transporter, while the uptake of the 1-Cy5.5-DF derivative was independent of the presence of a fructose-specific transporter. While 1-NBDF showed Glut5-specific accumulation, the coupling of a large fluorophore such as Cy5.5 likely introduces big structural and electronic changes, leading to a fructose derivative that does not accurately describe the uptake of fructose in cells. 相似文献
54.
Stankovic S Soldo B Beric-Bjedov T Knezevic-Vukcevic J Simic D Lazarevic V 《Systematic and applied microbiology》2007,30(1):8-15
A collection of 212 gram-positive bacilli isolated from natural habitats was screened for the presence of intervening sequences (introns and intein-coding sequences) in the SPbeta prophage-related ribonucleotide reductase genes bnrdE and bnrdF. Three novel configurations were identified on the basis of the presence of (i) intervening sequences in bnrdE and bnrdF, and (ii) an ORF in the bnrdE-bnrdF spacer. Analysis of the cell wall genetic determinants as well as of the incorporation of radio-labelled glycerol into cell wall allowed newly and previously identified B. subtilis strains with different configurations of bnrdE/bnrdF intervening sequences to be assigned to one of two subspecies. Strains apparently belonging to the subsp. subtilis contain three intervening sequences many of which are associated with the putative homing endonuclease activity. Strains of the subsp. spizizenii contain only one or two ORF-less group I introns. Introns occupying bnrdF are confined to the subspecies subtilis. 相似文献
55.
Performance analysis of MPI collective operations 总被引:1,自引:0,他引:1
Jelena Pješivac-Grbović Thara Angskun George Bosilca Graham E. Fagg Edgar Gabriel Jack J. Dongarra 《Cluster computing》2007,10(2):127-143
Previous studies of application usage show that the performance of collective communications are critical for high-performance
computing. Despite active research in the field, both general and feasible solution to the optimization of collective communication
problem is still missing.
In this paper, we analyze and attempt to improve intra-cluster collective communication in the context of the widely deployed
MPI programming paradigm by extending accepted models of point-to-point communication, such as Hockney, LogP/LogGP, and PLogP,
to collective operations. We compare the predictions from models against the experimentally gathered data and using these
results, construct optimal decision function for broadcast collective. We quantitatively compare the quality of the model-based
decision functions to the experimentally-optimal one. Additionally, in this work, we also introduce a new form of an optimized
tree-based broadcast algorithm, splitted-binary.
Our results show that all of the models can provide useful insights into various aspects of the different algorithms as well
as their relative performance. Still, based on our findings, we believe that the complete reliance on models would not yield
optimal results. In addition, our experimental results have identified the gap parameter as being the most critical for accurate
modeling of both the classical point-to-point-based pipeline and our extensions to fan-out topologies.
相似文献
Jack J. DongarraEmail: |
56.
Radović Jelena Suručić Relja Niketić Marjan Kundaković-Vasović Tatjana 《Molecular and cellular biochemistry》2022,477(7):1893-1903
Molecular and Cellular Biochemistry - Alchemilla viridiflora Rothm., Rosaceae is a herbaceous plant widespread in central Greece, Bulgaria, North Macedonia and Serbia with Kosovo. Liquid... 相似文献
57.
Matthew C. Clifton Michael J. Simon Satchal K. Erramilli Huide Zhang Jelena Zaitseva Mark A. Hermodson Cynthia V. Stauffacher 《The Journal of biological chemistry》2015,290(9):5555-5565
Bacterial ATP-binding cassette (ABC) importers are primary active transporters that are critical for nutrient uptake. Based on structural and functional studies, ABC importers can be divided into two distinct classes, type I and type II. Type I importers follow a strict alternating access mechanism that is driven by the presence of the substrate. Type II importers accept substrates in a nucleotide-free state, with hydrolysis driving an inward facing conformation. The ribose transporter in Escherichia coli is a tripartite complex consisting of a cytoplasmic ATP-binding cassette protein, RbsA, with fused nucleotide binding domains; a transmembrane domain homodimer, RbsC2; and a periplasmic substrate binding protein, RbsB. To investigate the transport mechanism of the complex RbsABC2, we probed intersubunit interactions by varying the presence of the substrate ribose and the hydrolysis cofactors, ATP/ADP and Mg2+. We were able to purify a full complex, RbsABC2, in the presence of stable, transition state mimics (ATP, Mg2+, and VO4); a RbsAC complex in the presence of ADP and Mg2+; and a heretofore unobserved RbsBC complex in the absence of cofactors. The presence of excess ribose also destabilized complex formation between RbsB and RbsC. These observations suggest that RbsABC2 shares functional traits with both type I and type II importers, as well as possessing unique features, and employs a distinct mechanism relative to other ABC transporters. 相似文献
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The aim of this study was to investigate the influence of experimental conditions on levothyroxine sodium release from two
immediate-release tablet formulations which narrowly passed the standard requirements for bioequivalence studies. The in vivo study was conducted as randomised, single-dose, two-way cross-over pharmacokinetic study in 24 healthy subjects. The in vitro study was performed using various dissolution media, and obtained dissolution profiles were compared using the similarity
factor value. Drug solubility in different media was also determined. The in vivo results showed narrowly passing bioequivalence. Considering that levothyroxine sodium is classified as Class III drug according
to the Biopharmaceutics Classification System, drug bioavailability will be less sensitive to the variation in its dissolution
characteristics and it can be assumed that the differences observed in vitro in some of investigated media probably do not have significant influence on the absorption process, as long as rapid and
complete dissolution exists. The study results indicate that the current regulatory criteria for the value of similarity factor
in comparative dissolution testing, as well as request for very rapid dissolution (more than 85% of drug dissolved in 15 min),
are very restricted for immediate-release dosage forms containing highly soluble drug substance and need further investigation.
The obtained results also add to the existing debate on the appropriateness of the current bioequivalence standards for levothyroxine
sodium products. 相似文献