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931.
Liu X Winrow VR Horrocks M Stevens CR 《Biochemical and biophysical research communications》2007,358(1):18-23
Abdominal aortic aneurysm (AAA) is commonly associated with atherosclerosis. Human AAA tissue displays cells undergoing all stages of apoptosis. Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis in tumour cells but not in normal cells. It has death receptors and decoy receptors. An inhibitor of TRAIL, osteoprotegerin (OPG), is involved in osteogenesis and vascular calcification. We investigated TRAIL and its receptors in AAA compared within normal aorta (NA). Both qualitative and quantitative analyses of calcification in AAA walls were determined using Von Kossa staining and pre-operation computer tomography (CT) scans. There was a significant difference in calcification level at different locations in the AAA wall (p <0.05). Apoptosis was confirmed in AAA by TUNEL assay. A significant difference in TRAIL and its receptor expression was observed between normal aortae and AAA (p<0.05). Significant differences were also observed between tissues displaying different extents of calcification for TRAIL mRNA (p<0.05) by RT-PCR examination and OPG protein (p<0.01) by protein blotting examination. We propose that this pattern of expression of TRAIL and its receptors may contribute to AAA formation and calcification in the AAA wall. 相似文献
932.
Research on dugong–seagrass interactions in Indonesia was done during the period 1990 until 2005 in respectively East Aru,
Maluku Province and East Kalimantan, Indonesia. This research investigated intensive rotational grazing by dugongs in intertidal
inshore Halodule univervis seagrass meadows, dugong movements in relation to these grazing swards, and analyses of parameters explaining the temporal
and spatial patterns of grazing in these meadows. In this paper, we report the findings of this long-term study. The patterns
of movement and the results of snorkelling surveys confirmed a practice of regular recropping of restricted grazing swards
by small feeding assemblages of dugongs. Dugong grazing showed a significant correlation with carbohydrate content of the
below-ground biomass and no significant relation with total N. The timing of dugong grazing in these intertidal meadows coincides
with high below-ground biomass and high carbohydrate content in the rhizomes of H. uninervis in the upper 0–4 cm sediment layer. Our findings support the hypothesis that temporal dugong grazing is ruled by carbohydrate
content in below-ground biomass. The mechanisms of rotational grazing in restricted grazing swards are not yet well understood,
and the maximisation of carbohydrates does not fully explain this phenomenon. Our research confirms that intertidal H. univervis seagrass meadows form a crucial resource for dugong survival. These relatively unknown biotopes need therefore more attention
in research and conservation programmes. 相似文献
933.
Photooxidation of wetland and riverine dissolved organic matter: altered copper complexation and organic composition 总被引:1,自引:0,他引:1
In natural waters, the uptake of transition metals such as copper (Cu) by aquatic biota depends on the activity of the free
cupric ion ({Cu2+}) rather than on total Cu concentration. Thus, an important ecological function of dissolved organic matter (DOM) in aquatic
ecosystems is Cu–DOM complexation, which greatly decreases the {Cu2+}. However, Cu bioavailability is greatly modified by source and environmental history of DOM because DOM affinity for Cu
varies by orders of magnitude among DOM sources; moreover, DOM is photochemically unstable. During 72-h irradiation experiments
at intensities approximating sunlight with DOM from a palustrine wetland and a third-order river, we investigated photooxidative
effects on DOM complexation of Cu as well as spectral and chemical changes in DOM that might explain altered Cu complexation.
Irradiation decreased Cu complexation by riverine DOM, but unexpectedly increased Cu complexation by wetland DOM, resulting
in 150% greater {Cu2+} in riverine DOM at the same dissolved organic carbon concentrations. The specific ultraviolet absorption (SUVa) and humic substances tracked photochemical changes in the conditional stability constants of Cu–DOM complexes, suggesting
that the aromaticity of DOM influences its affinity for Cu. Carbonyl concentration in 13C nuclear magnetic resonance spectra (13C-NMR) covaried directly with Cu binding-site densities in DOM. However, no aspect of Cu–DOM complexation consistently covaried
with fluorophores (i.e., the fluorescence index) or low molecular weight organic acids. Our results suggest that global increases
in UV radiation will affect Cu–DOM complexation and subsequent Cu toxicity depending on light regime as well as DOM source.
Handling editor: K. Martens 相似文献
934.
Paulina Bourosh Olga Bologa Nicolae Gerbeleu Maria Gdaniec 《Inorganica chimica acta》2007,360(10):3250-3254
Two complexes of gold of the compositions [Au(DMG)ClPy] (1) and [AuCl2Py2][AuCl4] · 2[AuCl3Py] (2), where H2DMG was dimethylglyoxime, were synthesized as the products of interaction of H[AuCl4] · 4H2O with H2DMG in the presence of pyridine and characterized by X-ray structural analysis. It was shown that depending on the synthetic conditions, the final product represents a molecular complex 1 or an ionic complex 2, in the latter one the charged and neutral species being combined via Au?Cl or Au?Au interactions. 相似文献
935.
Tiddo J. Mooibroek 《Inorganica chimica acta》2007,360(1):381-404
Supramolecular chemistry is a topical field of contemporary research whose current tremendous progress is aided by the development of crystal structure determination and theoretical studies, both resulting from considerable advances in computer science. Consequently, supramolecular interactions are more easily appraised, and even the weakest ones, such as anion-π contacts, can nowadays be investigated. The present paper gives an account on the different types of interactions encountered by the supramolecular chemist, with an emphasis on the remarkable 1,3,5-triazine ring which can experience all of them, namely coordination bonds, hydrogen bonding, electrostatic and charge-transfer attractions, and aromatic-stacking interactions. Indeed, a thorough search in the Cambridge Structure Database clearly shows that this simple 1,3,5-triazine synthon can be involved in all the categories of supramolecular interactions aforementioned. 相似文献
936.
Soma Sen Samiran Mitra David L. Hughes Georgina Rosair Cdric Desplanches 《Inorganica chimica acta》2007,360(15):4085-4092
Two new dicyanamide bridged 1D polynuclear copper(II) complexes [Cu(L1){μ1,5-N(CN)2}]n (1) [L1H = C6H5C(O)NHNC(CH3)C5H4N] and [Cu(L2){μ1,5-N(CN)2}]n (2) [L2H=C6H5C(O)CHC(CH3)NCH2CH2N(CH3)2] have been synthesised and structures of both the complexes and their crystal packing arrangements have been established by X-ray crystallography. For complex 1, a tridentate hydrazone ligand (L1H) obtained by the condensation of benzhydrazide and 2-acetylpyridine is used, whereas a tridentate Schiff base (L2H) derived from benzoylacetone and 2-dimethylaminoethylamine is employed for the preparation of complex 2. Variable temperature magnetic susceptibility measurement studies indicate there are weak antiferromagnetic interactions with J values −0.10 and −1.41 cm−1 for 1 and 2, respectively. 相似文献
937.
Dionysia Papagiannopoulou Ioannis Pirmettis Dimitri Komiotis Dimitra Benaki Aris Terzis 《Inorganica chimica acta》2007,360(11):3597-3602
Neutral, hexacoordinated “3 + 2” mixed ligand oxorhenium (1) and oxotechnetium (2) complexes of the general formula MO[SNO][NN], where M = Re or 99Tc, SNO is 2-mercaptoethyl-N-glycine and NN is 2,2′-bipyridine (bpy), were synthesized by simultaneous action of the tridentate SNO and the bidentate NN ligand on ReOCl3(PPh3)2 or 99TcO-gluconate precursors in a 1:1:1 molar ratio. Both complexes were characterized by elemental analysis, IR and NMR spectroscopy. X-ray structure determination of rhenium complex 1 revealed a distorted octahedral coordination geometry where the SNO donor atoms of the tridentate ligand and one bpy nitrogen atom occupy the equatorial positions of the octahedron, whereas the second bpy nitrogen atom and the oxo-group fill the apical positions. 相似文献
938.
Five cadmium halides with N-donor ligands were synthesized under the hydrothermal conditions and characterized by X-ray single-crystal diffraction. The isostructural [CdX2(2,2′-bpy)] (X = I 1, Br 2, bpy = bipyridine) (1) possess 3-D supramolecular network structures based on 1-D zigzag-type CdX2 chains extended by bpy molecules via non-covalent C-H?X hydrogen-bonded interactions. The 3-D porous [CdBr2(pip)] (pip = piperazine) (3) is formed through a linkage of 1-D zigzag-type CdBr2 chains by pip bridges. The heteronuclear dimetal-iodo cluster [Cu(phen)2CdI4] (phen = phenanthroline) (4) consists of a trigonal bipyramidal Cu(II) center and a tetrahedral Cd(II) center linked by a μ2-I bridge. The ionic [Co(dien)2][CdI4] (dien = diethylenetriamine) (5) comprises an octahedral cation and a tetrahedral anion. 相似文献
939.
This paper reports two tetranuclear manganese clusters, namely, [Mn4O2(O2CCH3)4(O3PC6H11)2(phen)2] (1) and [Mn4O2(O2CPh)4 (O3PC6H11)2(bpy)2] (2). Both contain a butterfly-like [Mn4(μ3-O)2]8+ core. The neighboring Mn atoms within the core are bridged by the carboxylate groups, forming approximately a plane. The phosphonate ligands locate above and below the plane, and cap on top of the Mn3O triangles by using its three phosphonate oxygen atoms. The magnetic measurements of complexes 1 and 2 reveal that dominant antiferromagnetic interactions are propagated between the magnetic centers. 相似文献
940.
Dennis Hasselquist ?rjan ?stman Jonas Waldenstr?m Staffan Bensch 《Journal of Ornithology》2007,148(4):401-409
We studied the prevalence and intensity of the haemosporidian blood parasite Haemoproteus payevskyi in great reed warblers at Lake Kvismaren (6 years) and Lake Segersj? (3 years) in Sweden. Based on microscopic inspection
of slides from 282 adult birds, 20.6% showed infection of H. payevskyi in circulating red blood cells in at least 1 year. For parasite prevalence, there was no difference between years, sex, and
age classes. However, parasite intensity was higher in females than in males, and this was most pronounced in 1-year-old birds.
Individuals scored to carry parasites in year
n
were more likely to show parasite infection year
n + 1 than birds scored to be parasite-free in year
n
. None of 99 juvenile birds examined at the breeding site in late summer, 4–9 weeks after hatching, showed infection of H. payevskyi. Parasite intensity in infected adult birds decreased in the course of the breeding season and no new or relapse infections
were observed during this period. Thus, our data imply that in the great reed warbler, a long-distance migrant to tropical
Africa, transmission of H. payevskyi occurs on wintering sites or at stopover sites during migration. 相似文献