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Complexes of Zn(II), Cu(II) and Co(II) with either N-(2-methylpyridyl)-3-thienyl-alkyl-carboxamide or N-(2-pyridyl)-3-thienylalkyl-carboxamide groups have been prepared and characterized. Crystal structures of ten new complexes are reported and discussed. N-(2-Methylpyridyl)-3-thienyl-alkyl-carboxamide exhibits both uni- and bidentate behavior. With all ligands, bidentate complexation is through the carbonyl oxygen and pyridine nitrogen atoms (O, N) and the amide nitrogen atom remains protonated. The electrochemical behavior and the infrared spectra of selected complexes are discussed. 相似文献
85.
Lorin A Lins L Stroobant V Brasseur R Charloteaux B 《Biochemical and biophysical research communications》2007,355(3):649-653
In this study, we determined the minimal N-terminal fusion peptide of the gp30 of the bovine leukemia virus on the basis of the tilted peptide theory. We first used molecular modelling to predict that the gp30 minimal fusion peptide corresponds to the 15 first residues. Liposome lipid-mixing and leakage assays confirmed that the 15-residue long peptide induces fusion in vitro and that it is the shortest peptide inducing optimal fusion since longer peptides destabilize liposomes to the same extent but not shorter ones. The 15-residue long peptide can thus be considered as the minimal fusion peptide. The effect of mutations reported in the literature was also investigated. Interestingly, mutations related to glycoproteins unable to induce syncytia in cell-cell fusion assays correspond to peptides predicted as non-tilted. The relationship between obliquity and fusogenicity was also confirmed in vitro for one tilted and one non-tilted mutant peptide. 相似文献
86.
Nanostructured agglomerated vesicles encapsulating ciprofloxacin were evaluated for modulated delivery from the lungs in a healthy rabbit model. An aliphatic disulfide crosslinker, cleavable by cysteine was used to form cross-links between nanosized liposomes to form the agglomerates. The blood levels of drug after pulmonary instillation of free ciprofloxacin, liposomal ciprofloxacin, and the agglomerated liposomes encapsulating ciprofloxacin were evaluated. The liposomes and agglomerated vesicles showed extended release of drug into the blood over 24 hours, while the free ciprofloxacin did not. The agglomerates also allowed modulation of the drug release rate upon the introduction of cysteine into the lungs post-drug instillation; the cysteine-cleavable agglomerates accelerated their drug release rate, indicated by an increased level of drug in the blood. This technology holds promise for the post-administration modulation of antibiotic release, for the prevention and treatment of pulmonary and systemic infections. 相似文献
87.
Binder H 《European biophysics journal : EBJ》2007,36(4-5):265-279
The ordering and H-bonding characteristics of the hydration water of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)
were studied using polarized infrared spectroscopy by varying either the temperature or the relative humidity of the ambient
atmosphere of multibilayer samples. The OH-stretching band of lipid-bound water was interpreted by a simplified two-state
model of well-structured, low density “network” water and of less-structured dense “multimer” water. The IR-spectroscopic
data reflect a rather continuous change of the water properties with increasing distance from the membrane and with changing
temperature. Network and multimer water distribute across the whole polar interphase with changing composition and orientation.
Upon dehydration the fraction of network water increases from about 30 to 60%, a value which is similar to that in supercooled
water at −25°C. The highly ordered gel phase gives rise to an increased fraction of structured network water compared with
the liquid crystalline phase. The IR order parameter shows that the water dipoles rearrange from a more parallel towards a
more perpendicular orientation with respect to the membrane normal with progressive hydration.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献
88.
To overcome positional and methylation effects on transgene expression, we developed a universal cloning cassette for in vivo assessment of regulatory elements using the luciferase reporter gene and the CCCD camera. Monitoring luciferase expression pattern in live mice enables screening of large numbers of transgenic founders quickly and inexpensively. We demonstrate that in the engineered transgenic mice, the chicken beta-globin 5'HS4 insulator did not always provide the desirable expression pattern, and the Island Element, responsible for the demethylation of the surrounding DNA region, was not beneficial. Both tested liver-specific and developmentally regulated promoters exhibited the expected expression pattern in most transgenic founders. 相似文献
89.
Use of digital webcam images to track spring green-up in a deciduous broadleaf forest 总被引:6,自引:0,他引:6
Richardson AD Jenkins JP Braswell BH Hollinger DY Ollinger SV Smith ML 《Oecologia》2007,152(2):323-334
Understanding relationships between canopy structure and the seasonal dynamics of photosynthetic uptake of CO2 by forest canopies requires improved knowledge of canopy phenology at eddy covariance flux tower sites. We investigated whether
digital webcam images could be used to monitor the trajectory of spring green-up in a deciduous northern hardwood forest.
A standard, commercially available webcam was mounted at the top of the eddy covariance tower at the Bartlett AmeriFlux site.
Images were collected each day around midday. Red, green, and blue color channel brightness data for a 640 × 100-pixel region-of-interest
were extracted from each image. We evaluated the green-up signal extracted from webcam images against changes in the fraction
of incident photosynthetically active radiation that is absorbed by the canopy (f
APAR), a broadband normalized difference vegetation index (NDVI), and the light-saturated rate of canopy photosynthesis (A
max), inferred from eddy flux measurements. The relative brightness of the green channel (green %) was relatively stable through
the winter months. A steady rising trend in green % began around day 120 and continued through day 160, at which point a stable
plateau was reached. The relative brightness of the blue channel (blue %) also responded to spring green-up, although there
was more day-to-day variation in the signal because blue % was more sensitive to changes in the quality (spectral distribution)
of incident radiation. Seasonal changes in blue % were most similar to those in f
APAR and broadband NDVI, whereas changes in green % proceeded more slowly, and were drawn out over a longer period of time. Changes
in A
max lagged green-up by at least a week. We conclude that webcams offer an inexpensive means by which phenological changes in
the canopy state can be quantified. A network of cameras could offer a novel opportunity to implement a regional or national
phenology monitoring program. 相似文献
90.
Kubodera T Koyama Y Mori K 《Proceedings. Biological sciences / The Royal Society》2007,274(1613):1029-1034
Our newly developed underwater high definition video camera system took the first live images of adults of the mesopelagic large squid, Taningia danae, between 240 and 940 m deep off Ogasawara Islands, western North Pacific. The resulting footage includes attacking and bioluminescence behaviours, and reveals that T. danae is far from the sluggish neutrally buoyant deep-sea squid previously suspected. It can actively swim both forward and backward freely by flapping its large muscular triangular fins and changes direction quickly through bending its flexible body. It can attain speeds of 2-2.5 ms(-1) (7.2-9 km h(-1)) when attacking bait rigs. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They also emitted long and short glows separated by intervals while wandering around the double torch lights attached to the bait rig, suggestive of potential courtship behaviours during mating. 相似文献