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921.
922.
Samia Aci-Sèche Norbert Garnier Stéphane Goffinont Daniel Genest Mélanie Spotheim-Maurizot Monique Genest 《European biophysics journal : EBJ》2010,39(10):1375-1384
The function of the E. coli lactose operon requires the binding of the tetrameric repressor protein to the operator DNA. We have previously shown that
γ-irradiation destabilises the repressor-operator complex because the repressor gradually loses its DNA-binding ability (Radiat
Res 170:604–612, 2008). It was suggested that the observed oxidation of tyrosine residues and the concomitant structural changes
of irradiated headpieces (DNA-binding domains of repressor monomers) could be responsible for the inactivation. To unravel
the mechanisms that lead to repressor-operator complex destabilisation when tyrosine oxidation occurs, we have compared by
molecular dynamic simulations two complexes: (1) the native complex formed by two headpieces and the operator DNA, and (2)
the damaged complex, in which all tyrosines are replaced by their oxidation product 3,4-dihydroxyphenylalanine (DOPA). On
a 20 ns time scale, MD results show effects consistent with complex destabilisation: increased flexibility, increased DNA
bending, modification of the hydrogen bond network, and decrease of the positive electrostatic potential at the protein surface
and of the global energy of DNA-protein interactions. 相似文献
923.
Stulova I Adamberg S Krisciunaite T Kampura M Blank L Laht TM 《Letters in applied microbiology》2010,51(6):683-690
Aims: The microbial quality of farm bulk‐tank raw milk produced in Estonia during years 2004–2007 was investigated. Methods and Results: Bulk‐tank milk samples were analysed for lactic acid bacteria count (LABC), psychrotrophic bacteria count (PBC), aerobic spore‐forming bacteria count (ASFBC), total bacterial counts using BactoScan and somatic cell count (SCC) using Fossomatic. Randomly selected psychrotrophic isolates were subjected to 16S–23S PCR‐ribotyping. LABC remained below 104 CFU ml?1 in most samples, while psychrotrophic micro‐organisms dominated in 60% of farms. PBC ranged from 4·2 × 102 to 6·4 × 104 CFU ml?1, and ASFBC varied from 5 to 836 CFU ml?1. Conclusions: In general, the microbiological quality of the farm bulk‐tank milk was good – more than 91% of samples contained <50 000 CFU ml?1, and SCC in the majority of samples did not exceed the internationally recommended limits. Genus Pseudomonas spp. was the dominating spoilage flora with Pseudomonas fluorescens as the prevailing species. Significance and Impact of the Study: Specific bacterial groups (LABC, PBC and ASFBC), not analysed routinely by dairies, were determined in bulk‐tank raw milk of numerous dairy farms during 4‐year period. Based on the survey, dairy plants can better control their supply chains and select farms (milk) for the production of specific products, i.e. milk with low PBC and high LABC for cheesemaking. 相似文献
924.
Alfred Barth Ivo Ponocny Elisabeth Ponocny‐Seliger Norbert Vana Robert Winker 《Bioelectromagnetics》2010,31(3):173-179
There is extensive literature on possible effects of extremely low‐frequency magnetic fields (ELF‐MFs) on human cognitive functions. However, due to methodological deficits (e.g., low statistical power, small sample sizes) findings have been inconsistent. In the current study we try to overcome these problems by carrying out a meta‐analysis. Literature research revealed 17 studies. Nine of these were included in the meta‐analysis because they fulfilled minimum requirements (e.g., at least single‐blind experimental study design and documentation of means and standard deviation of the dependent variables). All of the studies used a 50 Hz magnetic field exposure. Small but significant effect sizes could be detected in two cognitive dimensions: in the hard level of visual duration discrimination, task‐exposed subjects performed better than controls; at the intermediate level however, exposed subjects performed worse. Additionally, a significant improvement of correct responses was observed in the dimension of “flexibility” under exposure. However, due to the small number of studies per performance dimensions and the resulting instability of estimates, these findings have to be treated with extreme caution. Taken together, the results of the meta‐analysis provide little evidence that ELF‐MFs have any effects on cognitive functions. Bioelectromagnetics 31:173–179, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
925.
Christopher Blackburn Cynthia Barrett Jonathan L. Blank Frank J. Bruzzese Nancy Bump Lawrence R. Dick Paul Fleming Khristofer Garcia Paul Hales Zhigen Hu Matthew Jones Jane X. Liu Darshan S. Sappal Michael D. Sintchak Christopher Tsu Kenneth M. Gigstad 《Bioorganic & medicinal chemistry letters》2010,20(22):6581-6586
Starting from a tripeptide screening hit, a series of dipeptide inhibitors of the proteasome with Thr as the P3 residue has been optimized with the aid of crystal structures in complex with the β-5/6 active site of y20S. Derivative 25, (β5 IC50 = 7.4 nM) inhibits only the chymotryptic activity of the proteasome, shows cellular activity against targets in the UPS, and inhibits proliferation. 相似文献
926.
Norbert Gleicher Andrea Weghofer David H Barad 《Reproductive biology and endocrinology : RB&E》2010,8(1):64
Background
Follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) represent the two most frequently utilized laboratory tests in determining ovarian reserve (OR). This study determined the clinical significance of their concordance and discordance in female infertility patients.Methods
We investigated 366 consecutive infertility patients (350 reached IVF), excluding women with polycystic ovarian syndrome (PCOS). They were considered to have normal FSH and AMH if values fell within age-specific (as-) 95% confidence intervals (CI), and to suffer from diminished ovarian reserve (DOR) if FSH exceeded and/or AMH fell below those. The two hormones, thus, could be concordant (Group I), both normal (IA) or abnormal (IB), show normal AMH/abnormal FSH (Group II) or normal FSH/abnormal AMH (Group III). Oocyte yields, stratified for age categories, were then studied in each group as reflection of OR.Results
Oocyte yields significantly decreased from groups IA to II to III and IB. Predictive values of as-FSH/AMH patterns changed, however, at different ages. Except at very young and very old ages, normal as-AMH better predicted higher oocytes yields than normal as-FSH, though above age 42 years normal as-FSH predicts good oocyte yields even with abnormally low AMH. Under age 42 discrepancies between as- FSH and as-AMH remain similarly predictive of oocyte yields at all ages.Discussion
Concordances and discordances between as-FSH and as-AMH improve OR assessments and predictability of oocyte yields in IVF.927.
928.
929.
930.
Benjamin Krummel Alan Strassburg Martin Ernst Norbert Reiling Barbara Eker Heidrun Rath Robert Hoerster Waltraud Wappler Andrea Glaewe Volker Schoellhorn Giovanni Sotgiu Christoph Lange 《PloS one》2010,5(7)
Interferon (IFN)-γ release assays (IGRA) have improved tuberculosis contact tracing, but discrimination of recent from remote Mycobacterium tuberculosis contacts is not possible by IGRA alone. We present results of a tuberculosis contact investigation with a new early-secretory-antigenic-target (ESAT)-6 and culture-filtrate-protein (CFP)-10 specific interleukin (IL)-2 ELISpot in addition to ESAT-6 and CFP-10 specific IFN-γ ELISpot and tuberculin skin testing (TST). Results of the TST, IFN-γ ELISpot and IL-2 ELISpot were positive in 6/172 (3.4%), 7/167 (4.2%) and 6/196 (3.1%) of contacts, respectively. Close contact (≥100 hours) to the index case increased the risk of positive results in the IFN-γ ELISpot, TST, and IL-2 ELISpot by 40.8, 19.3, and 2.5 times, respectively. Individuals with a positive IFN-γ ELISpot/negative IL-2 ELISpot result had a median (IQR) duration of index case exposure of 568 hours (133_1000) compared to individuals with a positive IFN-γ ELISpot/positive IL-2 ELISpot result (median = 24 hours; 20_130; p-value = 0.047). Combination of a M. tuberculosis specific IFN-γ ELISpot with a M. tuberculosis specific IL-2 ELISpot significantly improved the identification of individuals with the highest risk of recent M. tuberculosis infection and is a promising method that should be explored to target tuberculosis preventive chemotherapy. 相似文献