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101.
Hill BC Becker L Anand V Kusmierczyk A Marcovina SM Rahman MN Gabel BR Jia Z Boffa MB Koschinsky ML 《Archives of biochemistry and biophysics》2003,412(2):186-195
Low-density lipoprotein (LDL) oxidation is stimulated by copper. Addition of a recombinant form of apolipoprotein(a) (apo(a); the distinguishing protein component of lipoprotein(a)) containing 17 plasminogen kringle IV-like domains (17K r-apo(a)) protects LDL against oxidation by copper. Protection is specific to apo(a) and is not achieved by plasminogen or serum albumin. When Cu(2+) is added to 17K r-apo(a), its intrinsic fluorescence is quenched in a concentration-dependent and saturable manner. Quenching is unchanged whether performed aerobically or anaerobically and is reversible by ethylenediaminetetraacetate, suggesting that it is due to equilibrium binding of Cu(2+) and not to oxidative destruction of tryptophan residues. The fluorescence change exhibits a sigmoid dependence on copper concentration, and time courses of quenching are complex. At copper concentrations below 10 microM there is little quenching, whereas above 10 microM quenching proceeds immediately as a double-exponential decay. The affinity and kinetics of copper binding to 17K r-apo(a) are diminished in the presence of the lysine analogue epsilon -aminocaproic acid. We propose that copper binding to the kringle domains of 17K is mediated by a His-X-His sequence that is located about 5A from the closest tryptophan residue of the lysine binding pocket. Copper binding may account for the natural resistance to copper-mediated oxidation of lipoprotein(a) relative to LDL that has been previously reported and for the protection afforded by apo(a) from copper-mediated oxidation of LDL that we describe in the present study. 相似文献
102.
Anna Amcheslavsky Mona?L. Wood Andriy?V. Yeromin Ian Parker J.?Alfredo Freites Douglas?J. Tobias Michael?D. Cahalan 《Biophysical journal》2015,108(2):237-246
Upon endoplasmic reticulum Ca2+ store depletion, Orai channels in the plasma membrane are activated directly by endoplasmic reticulum-resident STIM proteins to generate the Ca2+-selective, Ca2+ release-activated Ca2+ (CRAC) current. After the molecular identification of Orai, a plethora of functional and biochemical studies sought to compare Orai homologs, determine their stoichiometry, identify structural domains responsible for the biophysical fingerprint of the CRAC current, identify the physiological functions, and investigate Orai homologs as potential therapeutic targets. Subsequently, the solved crystal structure of Drosophila Orai (dOrai) substantiated many findings from structure-function studies, but also revealed an unexpected hexameric structure. In this review, we explore Orai channels as elucidated by functional and biochemical studies, analyze the dOrai crystal structure and its implications for Orai channel function, and present newly available information from molecular dynamics simulations that shed light on Orai channel gating and permeation. 相似文献
103.
To explore the feasibility of performing an epidemiologic study of female breast cancer and magnetic field (MF) exposures, we chose to study garment workers, who reportedly have some of the highest MF exposures. We collected personal exposure (PE, n = 48) and survey measurements (n = 77) near commercial sewing machines at three garment facilities and conducted a pilot interview among 25 garment workers asking about exposure duration, activities, and machine characteristics. MF levels were higher for older machines with alternating current (AC) than newer machines with direct current (DC) motors. MF levels were comparable for both idling and sewing activities. Most interviewed workers could describe duration of exposure and machine type (automatic/manual), but not other machine characteristics. Measurements were lower than previously reported for garment workers but were higher than exposures to most women. A historical exposure assessment can be conducted by linking duration of exposure with reconstructed exposure measurements but may be limited by the accuracy of work history data. 相似文献
104.
Mona Saleh Shaun Abbott Valérie Perron Caroline Lauzon Christopher Penney Boulos Zacharie 《Bioorganic & medicinal chemistry letters》2010,20(3):945-949
A series of 2-fluorophenyl-4,6-disubstituted [1,3,5]triazines (1) and (2) were synthesized and evaluated for their antimicrobial activity against three representative gram-positive bacteria and two fungi. The structure–activity relationship (SAR) demonstrates that the 3- or 4-fluorophenyl component attached directly to the triazine ring was essential for activity. Of these compounds, 14, 15, and 25 demonstrated significant activity against all selected organisms compared to control. These compounds were generally nontoxic and may prove useful as antimicrobial agents. 相似文献
105.
Spinosad is a bioinsecticide with a high degree of selective toxicity towards insects of different orders, but its toxicity
towards the two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is under debate. In this study, we compared the acaricidal properties of spinosad with the commercial
bioacaricide abamectin on the life stages of TSSM. Adulticide and ovicide bioassays were performed on a susceptible laboratory
strain using direct spraying of leaf disks with five rates of spinosad (20, 25, 30, 35 and 40 mg/l), five rates of abamectin
(0.125, 0.25, 0.5, 1 and 2.5 mg/l), sublethal concentrations or a combination of spinosad and abamectin. Both adulticidal
and ovicidal effects of spinosad against T. urticae in the laboratory were apparent, based on morality rates of the adults, reduction of female fecundity and death of offspring.
Abamectin was also found to significantly reduce female fecundity and killed offspring when applied directly on the eggs.
Interestingly, sublethal concentrations of spinosad reduced female fecundity stronger than abamectin. When a mixture of spinosad
and abamectin was applied at LC50, mortality was 74%, fecundity reduction was comparable to abamectin alone and egg hatching rate was lower than by either compound
alone. In conclusion, spinosad was more harmful than abamectin for TSSM life stages and the combined application is recommended. 相似文献
106.
Is microbial community composition in boreal forest soils determined by pH,C-to-N ratio,the trees,or all three? 总被引:11,自引:0,他引:11
In Fennoscandian boreal forests, soil pH and N supply generally increase downhill as a result of water transport of base cations
and N, respectively. Simultaneously, forest productivity increases, the understory changes from ericaceous dwarf shrubs to
tall herbs; in the soil, fungi decrease whereas bacteria increase. The composition of the soil microbial community is mainly
thought to be controlled by the pH and C-to-N ratio of the substrate. However, the latter also determines the N supply to
plants, the plant community composition, and should also affect plant allocation of C below ground to roots and a major functional
group of microbes, mycorrhizal fungi. We used phospholipid fatty acids (PLFAs) to analyze the potential importance of mycorrhizal
fungi by comparing the microbial community composition in a tree-girdling experiment, where tree belowground C allocation
was terminated, and in a long-term (34 years) N loading experiment, with the shifts across a natural pH and N supply gradient.
Both tree girdling and N loading caused a decline of ca. 45% of the fungal biomarker PLFA 18:2ω6,9, suggesting a common mechanism,
i.e., that N loading caused a decrease in the C supply to ectomycorrhizal fungi just as tree girdling did. The total abundance
of bacterial PLFAs did not respond to tree girdling or to N loading, in which cases the pH (of the mor layer) did not change
appreciably, but bacterial PLFAs increased considerably when pH increased across the natural gradient. Fungal biomass was
high only in acid soil (pH < 4.1) with a high C-to-N ratio (>38). According to a principal component analysis, the soil C-to-N
ratio was as good as predictor of microbial community structure as pH. Our study thus indicated the soil C-to-N ratio, and
the response of trees to this ratio, as important factors that together with soil pH influence soil microbial community composition. 相似文献
107.
Erdreich LS Van Kerkhove MD Scrafford CG Barraj L McNeely M Shum M Sheppard AR Kelsh M 《Radiation research》2007,168(2):253-261
Epidemiological studies of mobile phone use and risk of brain cancer have relied on self-reported use, years as a subscriber, and billing records as exposure surrogates without addressing the level of radiofrequency (RF) power output. The objective of this study was to measure environmental, behavioral and engineering factors affecting the RF power output of GSM mobile phones during operation. We estimated the RF-field exposure of volunteer subjects who made mobile phone calls using software-modified phones (SMPs) that recorded output power settings. Subjects recruited from three geographic areas in the U.S. were instructed to log information (place, time, etc.) for each call made and received during a 5-day period. The largest factor affecting energy output was study area, followed by user movement and location (inside or outside), use of a hands-free device, and urbanicity, although the two latter factors accounted for trivial parts of overall variance. Although some highly statistically significant differences were identified, the effects on average energy output rate were usually less than 50% and were generally comparable to the standard deviation. These results provide information applicable to improving the precision of exposure metrics for epidemiological studies of GSM mobile phones and may have broader application for other mobile phone systems and geographic locations. 相似文献
108.
Xiang MA Rybczynski PJ Patel M Chen RH McComsey DF Zhang HC Gunnet JW Look R Wang Y Minor LK Zhong HM Villani FJ Demarest KT Damiano BP Maryanoff BE 《Bioorganic & medicinal chemistry letters》2007,17(23):6623-6628
We have continued to explore spirobenzazepines as vasopressin receptor antagonists to follow up on RWJ-339489 (2), which had advanced into preclinical development. Further structural modifications were pursued to find a suitable backup compound for human clinical studies. Thus, we identified carboxylic acid derivative 3 (RWJ-676070; JNJ-17158063) as a potent, balanced vasopressin V(1a)/V(2) receptor antagonist with favorable properties for clinical development. Compound 3 is currently undergoing human clinical investigation. 相似文献
109.
Mona Hoppenrath Malte Elbrächter Hannelore Halliger Reinoud P. T. Koeman Alexander Krakhmalnyy Barbara Surek Katrin Erler Bernd Luckas 《Helgoland Marine Research》2007,61(3):157-165
Thecadinium yashimaense was recorded for the first time in France, Great Britain, The Netherlands, and Germany. The invasion and establishment of
the species in the German Bight was documented reliably and is presented here. The geographic expansion of the species from
the North Pacific to the North Atlantic Ocean is discussed. This bloom-forming, marine, sand-dwelling dinoflagellate was shown
to be non-toxic. Also Thecadinium kofoidii, the type species of the genus, was analyzed for potential toxin production and turned out to be non-toxic as well. 相似文献
110.
Hassan Mona M. Taha Rania A. Abd El-Aziz M. E. Shaaban Esam A. Ibrahim Eman A. 《Plant Cell, Tissue and Organ Culture》2022,148(1):73-80
Plant Cell, Tissue and Organ Culture (PCTOC) - Leaf chlorosis is often a problem in micropropagated Rubus idaeus, which makes successful acclimatization difficult. We found that... 相似文献