1,721,149 research outputs found
Metal chelation therapy and Parkinson’s disease: A critical review on the thermodynamics of complex formation between relevant metal ions and promising or established drugs
Full text linkThe present review reports a list of approximately 800 compounds which have been
used, tested or proposed for Parkinson’s disease (PD) therapy in the year range 2014–2019 (April):
name(s), chemical structure and references are given. Among these compounds, approximately 250
have possible or established metal-chelating properties towards Cu(II), Cu(I), Fe(III), Fe(II), Mn(II),
and Zn(II), which are considered to be involved in metal dyshomeostasis during PD. Speciation
information regarding the complexes formed by these ions and the 250 compounds has been collected
or, if not experimentally available, has been estimated from similar molecules. Stoichiometries and
stability constants of the complexes have been reported; values of the cologarithm of the concentration
of free metal ion at equilibrium (pM), and of the dissociation constant Kd (both computed at pH = 7.4
and at total metal and ligand concentrations of 106 and 105 mol/L, respectively), charge and
stoichiometry of the most abundant metal–ligand complexes existing at physiological conditions,
have been obtained. A rigorous definition of the reported amounts is given, the possible usefulness
of this data is described, and the need to characterize the metal–ligand speciation of PD drugs
is underlined
Revisiting Lead(II)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic Acid Coordination Chemistry in Aqueous Solutions: Evidence of an Underestimated Thermodynamic Stability
Full text linkThe complexes formed between Pb2+ and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were reinvestigated in aqueous solutions using a combination of pH potentiometry, UV-vis spectroscopy, and NMR spectroscopy. The thermodynamic data were supported by kinetics assays. Differently protonated complexes, i.e., [PbH3L]+, [PbH2L], [PbHL]-, and [PbL]2-, were detected, and the corresponding stability constants (logβ) at T = 298 K and I = 0.1 M NaCl were 33.1 ± 0.2, 32.00 ± 0.06, 29.28 ± 0.06, and 25.3 ± 0.1, respectively. Results differed significantly from those previously reported by Chaves et al. (Talanta 1992, 39, 249) and Pippin et al. (Inorg. Chim. Acta 1995, 239, 43) in both the speciation and the overall complex stability; the latter in particular was found to be remarkably higher. The work disclosed herein provides revised data on the Pb2+-DOTA complexes, which should be used as a new stability benchmark during the development of lead chelators
Unveiling the Decarboxylation of a Malonic Acid-Containing Macrocycle at Acidic pH: Implications and Applications of an Overlooked Phenomenon
Full text link1,10-Diaza-18-crown-6-1,10-bis(malonic acid) (oddm or macromal) is a promising chelator for large hard metal cations due to its unique structure, which combines the complexing properties of aza-crown Kryptofix 22 with those of malonic acid. This study uncovers the previously overlooked decarboxylation of macromal under mildly to strongly acidic pH conditions at room temperature. As a result, the acidity constants of macromal are carefully re-evaluated, providing precise data for its accurate and informed handling in aqueous media. The implications of these findings for metal complexation and new possible applications of macromal are also presented
Late Quaternary environmental events in two cores from Southern Joides Basin (Ross Sea, Antarctica).
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The Curies’ element: state of the art and perspectives on the use of radium in nuclear medicine
Full text linkBackground: The alpha-emitter radium-223 (Ra-223) is presently used in nuclear medicine for the palliative treatment of bone metastases from castration-resistant prostate cancer. This application arises from its advantageous decay properties and its intrinsic ability to accumulate in regions of high bone turnover when injected as a simple chloride salt. The commercial availability of [Ra-223]RaCl2 as a registered drug (Xofigo (R)) is a further additional asset. Main body: The prospect of extending the utility of Ra-223 to targeted alpha-therapy of non-osseous cancers has garnered significant interest. Different methods, such as the use of bifunctional chelators and nanoparticles, have been explored to incorporate Ra-223 in proper carriers designed to precisely target tumor sites. Nevertheless, the search for a suitable scaffold remains an ongoing challenge, impeding the diffusion of Ra-223-based radiopharmaceuticals. Conclusion: This review offers a comprehensive overview of the current role of radium radioisotopes in nuclear medicine, with a specific focus on Ra-223. It also critically examines the endeavors conducted so far to develop constructs capable of incorporating Ra-223 into cancer-targeting drugs. Particular emphasis is given to the chemical aspects aimed at providing molecular scaffolds for the bifunctional chelator approach
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Understanding the dynamics of West Nile virus in Emilia-Romagna, Italy
Full text linkWest Nile Virus (WNV) has been identified for the first time in Italy in 1998, and more
continuously since 2008 with a total of 173 neurological human cases between 2008 and 2015.
Still the circulation of the virus appears to have been episodic with most cases concentrated in a
few years and a few hotspots shifting in different years.
The region Emilia Romagna, which is one of the most affected areas, has set up since 2009 a
systematic program of mosquito and corvids (known to be among the most competent bird
species for WNV) trapping and testing. Data collected through this program have been analysed
through a mathematical model in order to understand the main drivers of the observed
dynamics.
The analysis has mainly been based on an SIR (for competent birds)-SI (mosquitoes) model,
with an environmentally driven population model, validated on independent data [1], for
mosquito dynamics, and a simple population model for bird dynamics, in which the free
parameters were the mosquito biting rate and the host-vector ratio.
Our results showed that simplest models with constant mosquito feeding behaviours are
incompatible with the observed seasonal patterns of infected mosquitoes and birds. On the
other hand, including a seasonal shift in mosquito feeding behaviour, as proposed in [2] and
confirmed also for Italy in [3], makes model outputs much more consistent with observed data.
Other improvements of the model allow for the age structure of the bird population, or for the
presence of other untested competent bird species. Finally, multi-year simulations of a spatiallystructured
model show a qualitative agreement with observed patterns of spatial spread.
Our findings can be of particular interest for public health policy makers, as they provide
important insights on WNV dynamics in order to improve surveillance, and risk assessment of
WNV in the area
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