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1.
The study of water relaxation rates of solutions of melanins with paramagnetic metal ions provides a powerful tool for investigating the binding sites and for obtaining useful structural and dynamic information. The measure of 1H- and 2H-longitudinal and transverse relaxation rates at a single, high-magnetic field for H2O/D2O (80:20) solutions allows the determination of tau c, tau R, tau e, tau M, r, q, and Z (the outer sphere contribution to the overall relaxation rate) for Mn(II)-L-Dopa melanin system. 相似文献
2.
Domenico Osella Silvio Aime Danilo Boccardo Mario Castiglioni Luciano Milone 《Inorganica chimica acta》1985,100(1):97-105
The [Co2(CO)6(RC2R′)] complexes (R, R′ = H, Me, Et, Prn) react with molecular hydrogen under mild conditions of temperature and pressure, at low but appreciable rates. The effect of the steric hindrance of the substituents and the strength of the metalcarbon bonds are discussed. The kinetic data measured for [Co2(CO)6(HC2H)], suggest that both H2-coordination and CO-dissociation are involved in the rate-determining step of the overall hydrogenation process.The catalytic activity of [Co2(CO)6(HC2H)] in the homogeneous hydrogenation of acetylene is described. At low substrate/catalyst ratio the initial hydrogenation rate is equal, within experimental error, to that found for the stoichiometric reaction; on increasing the acetylene concentration, cyclotrimerization to benzene becomes the dominant process. Interestingly C4 hydrocarbons (mainly butadiene and 1-butene) are produced in measurable yield (?8%). The formation of these products is interpreted as the result of the hydrogenation of the elusive [Co2(CO)5(HC2H)2] complex, an unstable intermediate in the cyclotrimerization chain. 相似文献
3.
S. Aime Mauro Botta S. Geninatti Crich Giovanni B. Giovenzana Roberto Pagliarin Maurizio Piccinini Massimo Sisti Enzo Terreno 《Journal of biological inorganic chemistry》1997,2(4):470-479
A novel heptacoordinating ligand consisting of a thirteen-membered tetraazamacrocycle containing the pyridine ring and bearing
three methylenephosphonate groups (PCTP-[13]) has been synthesized. Its Gd(III) complex displays a remarkably high longitudinal
water proton relaxivity (7.7 mM–1 s–1 at 25 °C, 20 MHz and pH 7.5) which has been accounted for in terms of contributions arising from (1) one water molecule
bound to the metal ion, (2) hydrogen-bonded water molecules in the second coordination sphere, or (3) water molecules diffusing
near the paramagnetic chelate. Variable-temperature 17O-NMR transverse relaxation data indicate that the residence lifetime of the metal-bound water molecule is very short (8.0 ns
at 25 °C) with respect to the Gd(III) complexes currently considered as contrast agents for magnetic resonance imaging. Furthermore,
GdPCTP-[13] interacts with human serum albumin (HSA), likely through electrostatic forces. By comparing water proton relaxivity
data for the GdPCTP-[13]-HSA adduct, measured as a function of temperature and magnetic field strength, with those for the
analogous adduct with GdDOTP (a twelve-membered tetraaza macrocyclic tetramethylenephosphonate complex lacking a metal-bound
water molecule), it has been possible to propose a general picture accounting for the main determinants of the relaxation
enhancement observed when a paramagnetic Gd(III) complex is bound to HSA. Basically, the relaxation enhancement in these systems
arises from (1) water molecules in the hydration shell of the macromolecule and protein exchangeable protons which lie close
to the interaction site of the paramagnetic complex and (2) the metal bound water molecule(s). As far as the latter contribution
is concerned, the interaction with the protein causes an elongation of the residence lifetime of the metal-bound water molecule,
which limits, to some extent, the potential relaxivity enhancement expected upon the binding of the paramagnetic complex to
HSA.
Received: 27 January 1997 / Accepted: 12 May 1997 相似文献
4.
Pickering Gisele P.; Fellmann Nicole; Morio Beatrice; Ritz Patrick; Amonchot Aime; Vermorel Michel; Coudert Jean 《Journal of applied physiology》1997,83(4):1300-1306
Pickering, Gisèle P., Nicole Fellmann, BéatriceMorio, Patrick Ritz, Aimé Amonchot, Michel Vermorel, and JeanCoudert. Effects of endurance training on the cardiovascularsystem and water compartments in elderly subjects. J. Appl. Physiol. 83(4): 1300-1306, 1997.Theeffects of endurance training on the water compartments and thecardiovascular system were determined in 10 elderly subjects [age62 ± 2 yr, pretraining maximal oxygen consumption(O2 max)/kg = 25 ± 2 ml · min1 · kg1body wt]. They trained on a cycloergometer 3 times/wk for 16 wk(50-80%O2 max,then 80-85%O2 max). They werechecked at 8 wk, 16 wk, and 4 mo after detraining. Training improvedO2 max (+16%) andinduced plasma volume expansion (+11%). No change in total body water,extracellular fluid, interstitial and intracellular fluid volumes,fat-free mass, and body weight was detected in this small sample withtraining. Body fat mass decreased (2.1 ± 2.2 kg).Echocardiography at rest showed increased fractional shortening andejection fraction and decreased left ventricular end-systolic dimension(P < 0.05). Blood volume expansioncorrelates with cardiac contractility and has an impact on cardiacfunction. These improvements are precarious, however, and arecompletely lost after 4 mo of detraining, when elderly subjects losethe constraints and the social stimulation of the imposed protocol. 相似文献
5.
Mélanie Aye Carole Di Giorgio Isabelle Berque-Bestel Ahissan Aime Benoit P. Pichon Yves Jammes Philippe Barthélémy Michel De Méo 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2013,750(1-2):129-138
We proposed to evaluate the genotoxicity and mutagenicity of a new quantum dots (QDs) nanoplatform (QDsN), consisting of CdSe/ZnS core–shell QDs encapsulated by a natural fusogenic lipid (1,2-di-oleoyl-sn-glycero-3-phosphocholine (DOPC)) and functionalized by a nucleolipid N-[5′-(2′,3′-di-oleoyl) uridine]-N′,N′,N′-trimethylammoniumtosylate (DOTAU). This QDs nanoplatform may represent a new therapeutic tool for the diagnosis and treatment of human cancers. The genotoxic, mutagenic and clastogenic effects of QDsN were compared to those of cadmium chloride (CdCl2). Three assays were used: (1) the Salmonella/microsome assay with four tester strains, (2) the comet assay and (3) the micronucleus test on CHO cells. The contribution of simulated sunlight was studied in the three assays while oxidative events were only explored in the comet assay in aliquots pretreated with the antioxidant l-ergothioneine. We found that QDsN could enter CHO-K1 cells and accumulate in cytoplasmic vesicles. It was not mutagenic in the Salmonella/mutagenicity test whereas CdCl2 was weakly positive. In the dark, both the QDsN and CdCl2 similarly induced dose-dependent increases in single-strand breaks and micronuclei. Exposure to simulated sunlight significantly potentiated the genotoxic activities of both QDsN and CdCl2, but did not significantly increase micronucleus frequencies. l-Ergothioneine significantly reduced but did not completely suppress the DNA-damaging activity of QDsN and CdCl2. The present results clearly point to the genotoxic properties and the risk of long-term adverse effects of such a nanoplatform if used for human anticancer therapy and diagnosis in the future. 相似文献
6.
The genus Meira currently contains three recently described species of mite-associated basidiomycete yeasts from Israel and Japan and is placed in the Exobasidiomycetes (Ustilaginomycotina) Incertae sedis. A previously undescribed species of Meira was isolated from the phylloplane of a magnolia leaf in Louisiana, USA. Herein, we describe Meira miltonrushii sp. nov. and include phylogenetic analyses from three rDNA loci to resolve the placement of Meira. This study provides evidence that Meira belongs to the family Brachybasidiaceae in the Exobasidiales and supports the placement of another mite-associated yeast genus, Acaromyces, within Cryptobasidiaceae (Exobasidiales). We also examine sequences produced by numerous environmental studies that suggest Meira species can be found as endophytes of many plant species. To our knowledge, this is the first record of a member of the genus Meira in North America. 相似文献
7.
Jena R. Hickey Janet Nackoney Nathan P. Nibbelink Stephen Blake Aime Bonyenge Sally Coxe Jef Dupain Maurice Emetshu Takeshi Furuichi Falk Grossmann Patrick Guislain John Hart Chie Hashimoto Bernard Ikembelo Omari Ilambu Bila-Isia Inogwabini Innocent Liengola Albert Lotana Lokasola Alain Lushimba Fiona Maisels Joel Masselink Valentin Mbenzo Norbert Mbangia Mulavwa Pascal Naky Nicolas Mwanza Ndunda Pele Nkumu Valentin Omasombo Gay Edwards Reinartz Robert Rose Tetsuya Sakamaki Samantha Strindberg Hiroyuki Takemoto Ashley Vosper Hjalmar S. Kühl 《Biodiversity and Conservation》2013,22(13-14):3085-3104
Habitat loss and hunting threaten bonobos (Pan paniscus), Endangered (IUCN) great apes endemic to lowland rainforests of the Democratic Republic of Congo. Conservation planning requires a current, data-driven, rangewide map of probable bonobo distribution and an understanding of key attributes of areas used by bonobos. We present a rangewide suitability model for bonobos based on a maximum entropy algorithm in which data associated with locations of bonobo nests helped predict suitable conditions across the species’ entire range. We systematically evaluated available biotic and abiotic factors, including a bonobo-specific forest fragmentation layer (forest edge density), and produced a final model revealing the importance of simple threat-based factors in a data poor environment. We confronted the issue of survey bias in presence-only models and devised a novel evaluation approach applicable to other taxa by comparing models built with data from geographically distinct sub-regions that had higher survey effort. The model’s classification accuracy was high (AUC = 0.82). Distance from agriculture and forest edge density best predicted bonobo occurrence with bonobo nests more likely to occur farther from agriculture and in areas of lower edge density. These results suggest that bonobos either avoid areas of higher human activity, fragmented forests, or both, and that humans reduce the effective habitat of bonobos. The model results contribute to an increased understanding of threats to bonobo populations, as well as help identify priority areas for future surveys and determine core bonobo protection areas. 相似文献
8.
9.
Amy?Y.?RossmanEmail author M.?Cathie Aime David?F.?Farr Lisa?A.?Castlebury Kristin?R.?Peterson Robert?Leahy 《Mycological Progress》2004,3(4):275-290
The coelomycetous genera Chaetomella and Pilidium were determined to be closely related to each other, yet are recognized as distinct genera based on both morphological observations
and rDNA sequence analyses. Analyses of the SSU and LSU of the nuclear ribosomal RNA genes suggest that Chaetomella and Pilidium along with Sphaerographium tenuirostrum and Synchaetomella lunatospora constitute a distinct lineage within the ascomycetes that is allied with the Leotiomycetes. Chaetomella and Pilidium both produce black pycnidia generally opening by a raphe, acropleurogenous conidiogenous cells, and non-septate, hyaline,
usually fusiform to falcate, rarely ellipsoid, conidia. Pycnidia of Pilidium are smooth while those of Chaetomella have setae of various types. A Hainesia sporodochial synanamorph was observed in cultures of C. oblonga and C. raphigera similar to H. lythri, the synanamorph of P. concavum. Specimens of C. oblonga, type species of Chaetomella, C. acutiseta, C. circinoseta, C. raphigera, Pilidium acerinum, type species of Pilidium, and P. concavum were examined. Diagnoses and illustrations are provided for these species along with a key to the accepted species in both
genera.
Mention of trade names or commercial products in this article is solely for the purpose of providing specific information
and does not imply recommendation or endorsement by the U.S. Department of Agriculture. 相似文献
10.