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排序方式: 共有735条查询结果,搜索用时 31 毫秒
181.
Raúl Chiozzone Ricardo González Donatella Armentano Juan Faus 《Inorganica chimica acta》2006,359(7):2194-2200
The reaction of K2[ReX6] (X = Cl, Br) with oxalic acid and triethylamine in dimethylformamide solution yields the substituted complexes [ReX4(ox)]2− and cis-[ReX2(ox)2]2−, which can be obtained separately depending on the amount of added amine. The crystal structures of (PPh4)2[ReBr4(ox)], cis-(PPh4)2[ReBr2(ox)2] and cis-(AsPh4)2[ReCl2(ox)2] have been determined by single-crystal X-ray diffraction. The anionic complexes are octahedral with only slight distortions. The direct isolation of the pure complexes as well as the formation of only the cis isomers - without the presence of trans isomers and/or [Re(ox)3]2− - is probably due to the kinetic inertness of Re(IV)-X bonds, which increases with the number of oxalato ligands bound to the metal ion. 相似文献
182.
Antimicrobial peptides (AMPs) are evolutionarily old components of innate immunity found in all living pluricellular organisms. Interestingly, some organisms express families of AMPs with only a slight variation among their members, possibly to increase their spectrum of activity. Despite the growing body of knowledge about their biological activity and mode of action on bacteria, only a few of them have been tested on Leishmania, a worldwide spread protozoan pathogen, and the parameters contributing to this activity are yet to be determined. We report on the anti-Leishmania activity and mode of action of bombinins H2 and H4 isolated from the skin secretion of the frog Bombina variegata. H4, the most active, is the first natural AMP of animal origin with a single L- to D-amino acid isomerization. Membrane depolarization and membrane permeation assays, as well as electron microscopy, suggest that the lethal mechanism involves plasma membrane permeation and/or disruption. To better understand the enhanced activity of H4, we determined the peptide's structure in membranes mimicking those of mammals, bacteria, and Leishmania by using ATR-FTIR and CD spectroscopies and assessed their membrane binding by using surface plasmon resonance. The data reveal that (i) H2 but not H4 partially aggregates in membranes mimicking those of Leishmania, (ii) H2 is slightly more helical than H4 in all membranes, and (iii) H4 binds the Leishmania model membrane approximately 5-fold better than H2. This study highlights the importance of a single alpha-amino acid epimerization as a tool used by nature to modulate the activity of AMPs. In addition, our findings suggest bombinins H as potential templates for the development of new drugs with a new mode of action against Leishmania. 相似文献
183.
Brisinda D Caristo ME Fenici R 《American journal of physiology. Heart and circulatory physiology》2006,291(1):H368-H378
Magnetocardiography (MCG) is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps in intact rats by means of MCG mapping. Twenty-four adult Wistar rats (12 male and 12 female) were studied, under anesthesia, with the same unshielded 36-channel MCG instrumentation used for clinical recordings. Two sets of measurements were obtained from each animal: 1) at 5 mo of age (297.5 +/- 21 g body wt) and 2) at 14 mo of age (516.8 +/- 180 g body wt). RR and PR intervals, QRS segment, and QTpeak, QTend, JTpeak, JTend, and Tpeak-end were measured from MCG waveforms. MCG imaging was automatically obtained as MF maps and as inverse localization of cardiac sources with equivalent current dipole and effective magnetic dipole models. After 300 s of continuous recording were averaged, the signal-to-noise ratio was adequate for study of atrial and ventricular MF maps and for three-dimensional localization of the underlying cardiac sources. Clear-cut age-related differences in VR duration were demonstrated by significantly longer QTend, JTend, and Tpeak-end in older Wistar rats. Reproducible multisite noninvasive cardiac mapping of anesthetized rats is simpler with MCG methodology than with ECG recording. In addition, MCG mapping provides new information based on quantitative analysis of MF and equivalent sources. In this study, statistically significant age-dependent variations in VR intervals were found. 相似文献
184.
185.
Roberto Della Pergola Luigi Garlaschelli Carlo Manassero Donatella Strumolo Emanuela Grigiotti 《Inorganica chimica acta》2009,362(2):331-338
The reaction between [Fe2Ir2(CO)12]2− and diphenylacetylene in refluxing CH3CN yields the substituted cluster [Fe2Ir2(CO)10(PhC2Ph)]2− (1). In the crystals, the four metal atoms define a butterfly arrangement whose Ir-Ir hinge is parallel to the acetylenic C2 unit. The neutral triangular cluster [FeIr2(CO)9(PhC2Ph)] (2) is obtained by the treatment of 1 with acids at room temperature; in this 48 valence electrons species, the C-C and the Ir-Ir bonds are also parallel, in the coordination mode.The cluster [Fe2Rh(CO)10]− reacts with diphenylacetylene in refluxing THF yielding [Fe2Rh(CO)8(PhC2Ph)]− (3). In this 46 C.V.E.’s cluster, the C2 unit is perpendicular to the Fe-Fe edge, exemplifying the bonding mode. According to 13C NMR spectra, the structure of the three clusters is maintained in solution. Electrochemical investigations show that the one-electron oxidation of [Fe2Ir2(CO)10(L)]2− (L = 2CO, PhC2Ph) as well as the one-electron reduction of [Fe2Rh(CO)8(PhC2Ph)]− only generates the respective short lived products. 相似文献
186.
Emanuele Brambilla Pisoni Roberto Raccanelli Giovanni Dotelli Donatella Botta Paco Melià 《The International Journal of Life Cycle Assessment》2009,14(3):248-256
Background, aim, and scope Many recent studies on waste management have described in detail the potential impacts of recycling and final treatment of
municipal waste. In public debates, the attention has also been focused on the choice of final disposal technologies (e.g.
landfilling vs. incineration). However, a comprehensive assessment of the impacts of waste collection and transport was still
lacking. In the present study, we use LCA to evaluate the potential impact of the provincial waste management plan of Varese
(northern Italy). Particular attention is devoted to the estimation of environmental impacts generated during waste transport.
Materials and methods A detailed Life Cycle Inventory was built for the transportation phase, based on primary data collected by interviewing the
agencies involved in waste collection. To model the recycling and final disposal phase we relied on the BUWAL 250 database.
Impacts were evaluated with the Eco-Indicator 99 method in its egalitarian formulation.
Results The results of our analysis reveal that the major potential impacts of the plan are associated with waste collection and transport.
These impacts are partially compensated by reduced resource consumption through recycling and energy recovery through incineration.
Discussion The outputs of the LCIA were compared with those obtained by using other ecoindicators (Eco-Indicator 99 hierarchist and individualist,
CML2, EPS2000). Although not comparable on a quantitative basis, they are qualitatively consistent.
Conclusions Neglecting the effects of collection and transport might result in a severe underestimation of the environmental impacts of
a waste management system, especially as refers to depletion of fossil fuels, emission of respiratory inorganics and climate
change. To reduce the environmental impact of waste management systems, an accurate optimisation of waste transport is required.
Recommendations and perspectives Effective waste management planning requires the explicit inclusion of waste collection and transport when comparing alternative
management policies. 相似文献
187.
188.
Lotta Koskinen Jihane Romanos Katri Kaukinen Kirsi Mustalahti Ilma Korponay-Szabo Donatella Barisani Maria Teresa Bardella Fabiana Ziberna Serena Vatta György Széles Zsuzsa Pocsai Kati Karell Katri Haimila Róza Ádány Tarcisio Not Alessandro Ventura Markku Mäki Jukka Partanen Cisca Wijmenga Päivi Saavalainen 《Immunogenetics》2009,61(4):247-256
Human leukocyte antigen (HLA) genes, located on chromosome 6p21.3, have a crucial role in susceptibility to various autoimmune
and inflammatory diseases, such as celiac disease and type 1 diabetes. Certain HLA heterodimers, namely DQ2 (encoded by the
DQA1*05 and DQB1*02 alleles) and DQ8 (DQA1*03 and DQB1*0302), are necessary for the development of celiac disease. Traditional
genotyping of HLA genes is laborious, time-consuming, and expensive. A novel HLA-genotyping method, using six HLA-tagging
single-nucleotide polymorphisms (SNPs) and suitable for high-throughput approaches, was described recently. Our aim was to
validate this method in the Finnish, Hungarian, and Italian populations. The six previously reported HLA-tagging SNPs were
genotyped in patients with celiac disease and in healthy individuals from Finland, Hungary, and two distinct regions of Italy.
The potential of this method was evaluated in analyzing how well the tag SNP results correlate with the HLA genotypes previously
determined using traditional HLA-typing methods. Using the tagging SNP method, it is possible to determine the celiac disease
risk haplotypes accurately in Finnish, Hungarian, and Italian populations, with specificity and sensitivity ranging from 95%
to 100%. In addition, it predicts homozygosity and heterozygosity for a risk haplotype, allowing studies on genotypic risk
effects. The method is transferable between populations and therefore suited for large-scale research studies and screening
of celiac disease among high-risk individuals or at the population level.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Lotta Koskinen and Jihane Romanos are authors with equal contribution. 相似文献
189.
190.
Viviana Cavalca Fabiana Minardi Samuele Scurati Isabella Squellerio Luca Dainese Elena Tremoli Donatella Caruso 《Analytical biochemistry》2010,397(2):168-174
Both F2-isoprostanes (8-iso-PGF2α), a well-known marker of oxidative stress, and thromboxanes A2 (TXA2) are involved in atherosclerosis through LDL oxidation and platelet activation. Different aspects of the pathology can be described by 8-iso-PGF2α and TXA2 so it is important to determine both their concentrations to monitor the disease progression and/or therapy effects. We developed a simple and sensitive method based on liquid chromatography-tandem mass spectrometry, using electrospray ionization in negative-ion mode, for the simultaneous measurement of the concentration of 8-iso-PGF2α and 11-dehydro thromboxane B2 (11-DH-TXB2), a TXA2 metabolite. This method was applied to analyze urine samples collected overnight from 15 atherosclerotic patients, with documented carotid artery sclerosis (CAS), and from 20 controls. The detection limit was 0.097 pg/μL for 8-iso-PGF2α and 0.375 pg/μL for 11-DH-TXB2, with a linear range of 0.78-25 pg/μL; the inter- and intraday imprecision was <5% for both metabolites. These analytes were higher in CAS (P < 0.005 vs controls) and were positively correlated in patients but not in controls, even after adjustment for age and gender (r = 0.60; P = 0.032). This highly sensitive, precise, and rapid method allows for the simultaneous determination of 8-iso-PGF2α and 11-DH-TXB2 in human urine samples in order to evaluate oxidative stress and platelet aggregation. 相似文献