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1.
Gels ; 10(4)2024 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-38667668

RESUMO

Raman spectroscopy is a non-destructive analytical technique for characterizing organic and inorganic materials with spatial resolution in the micrometer range. This makes it a method of choice for space-mission sample characterization, whether on return or in situ. To enhance its sensitivity, we use signal amplification via interaction with plasmonic silver-based colloids, which corresponds to surface-enhanced Raman scattering (SERS). In this study, we focus on the analysis of biomolecules of prebiotic interest on extraterrestrial dust trapped in silica aerogel, jointly with the Japanese Tanpopo mission. The aim is twofold: to prepare samples as close as possible to the real ones, and to optimize analysis by SERS for this specific context. Serpentinite was chosen as the inorganic matrix and adenine as the target biomolecule. The dust was projected at high velocity into the trapping aerogel and then mechanically extracted. A quantitative study shows effective detection even for adenine doping from a 5·10-9mol/L solution. After the dust has been expelled from the aerogel using a solvent, SERS mapping enables unambiguous adenine detection over the entire dust surface. This study shows the potential of SERS as a key technique not only for return samples, but also for upcoming new explorations.

2.
Chempluschem ; : e202300642, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38226922

RESUMO

The polymerization of unactivated amino acids (AAs) is an important topic because of its applications in various fields including industrial medicinal chemistry and prebiotic chemistry. Silica as a promoter for this reaction, is of great interest owing to its large abundance and low cost. The amide/peptide bond synthesis on silica has been largely demonstrated but suffers from a lack of knowledge regarding its reaction mechanism, the key parameters, and surface features that influence AA adsorption and reactivity, the selectivity of the reaction product, the role of water in the reaction, etc. The present review addresses these problems by summarizing experimental and modeling results from the literature and attempts to rationalize some apparent divergences in published results. After briefly presenting the main types of silica surface sites and other relevant macroscopic features, we discuss the different deposition procedures of AAs, whose importance is often neglected. We address the possible AA adsorption mechanisms including covalent grafting and H-bonding and show that they are highly dependent on silanol types and density. We then consider how the adsorption mechanisms determine the occurrence and outcome of AA condensation (formation of cyclic dimers or of long linear chains), and outline some recent results that suggest significant polymerization selectivity in systems containing several AAs, as well as the formation of specific elements of secondary structure in the growing polypeptide chains.

3.
Chembiochem ; 24(10): e202300143, 2023 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-37042352

RESUMO

Ring-closure is a key step in current pyrimidine anabolism and one may wonder whether cyclisation reactions could be promoted in the geochemical context at the origins of life, i. e. with the help of minerals. Various prebiotic minerals were tested in this work, including silica, carbonates, microporous minerals. In particular, the role of zinc ions supported on minerals was investigated in view of its presence in the catalytic site of cyclic amidohydrolase enzymes. Based on in situ (TGA: ThermoGravimetric Analysis, ATR-IR: Attenuated Total Reflectance-InfraRed) and ex situ (1 H NMR- Nuclear Magnetic Resonance) characterisations, we identified the products of thermal activation of NCA (N-carbamoyl-aspartic acid) in wetting-and-drying scenarios on the surface of minerals. NCA can cyclize extensively only on some surfaces, with the predominant product being 5-carboxymethylhydantoin (Hy) rather than dihydroorotate (DHO), while there is a competition with hydrolysis on others. Replacing the enzymes with heterogeneous catalysts also works with other reactions catalysed by enzymes of the cyclic amidohydrolases family. The role of the hydrophilicity/hydrophobicity of minerals as well as the regioselectivity of the cyclisation (5-carboxymethylhydantoin versus dihydroorotate) are examined.


Assuntos
Amidoidrolases , Ácido Aspártico , Hidantoínas , Minerais , Origem da Vida , Minerais/síntese química , Minerais/química , Domínio Catalítico , Zinco/química , Amidoidrolases/química , Ciclização , Ácido Aspártico/química , Hidantoínas/química
4.
Chemistry ; 29(22): e202204010, 2023 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-36748307

RESUMO

The parameters that determine the formation of linear peptides and cyclic dimers (diketopiperazine, DKP) on silica surfaces of different surface area, silanol and siloxane ring populations, controlled by thermal treatments, are investigated upon glycine deposition from gas and liquid phases. The formed products were characterized by infrared and Raman spectroscopies, X-ray diffraction and thermogravimetric analysis. The results reveal the importance of "nearly-free" silanols to form ester centers as primers for the formation of linear peptides over DKP, on surfaces with medium silanol density (1.4 to 2.7 nm-2 ). Quenched reactivity is seen on isolated silanols (density≤0.7 nm-2 ), while silanols involved in hydrogen bonding (density of 4.5 nm-2 ) weakly interact with Gly resulting in its cyclization to DKP. Deposition of glycine from liquid phase may also form both DKP and linear polymers, depending on its loading and silica surface. These conclusions demonstrate the complexity of glycine surface chemistry in the polymerization reaction and highlight the interest of a surface science approach to evaluate geochemical prebiotic scenarios.

5.
J Phys Chem B ; 127(3): 673-684, 2023 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-36637235

RESUMO

Peptide formation by amino acids condensation represents a crucial reaction in the quest of the origins of life as well as in synthetic chemistry. However, it is still poorly understood in terms of efficiency and reaction mechanism. In the present work, peptide formation has been investigated through thermal condensation of gas-phase glycine in fluctuating silica environments as a model of prebiotic environments. In-situ IR spectroscopy measurements under a controlled atmosphere reveal that a humidity fluctuating system subjected to both temperature and water activity variations results in the formation of more abundant peptides compared to a dehydrated system subjected only to temperature fluctuations cycles. A model is proposed in which hydration steps result in the hydrolysis and redistribution of the oligomers formed during previous deposition in dry conditions. This results in the formation of self-assembled aggregates with well-defined secondary structures (especially ß-sheets). Upon further monomers feeding, structural elements are conserved in newly growing chains, with indications of templated polymerization. The structural dynamics of peptides were also evaluated. Rigid self-assembled structures with a high resistance to further wetting/drying cycles and inaccessibility to isotopic exchange were present in the humidity fluctuating system compared to more flexible structures in the dehydrated system. The resistance and growth of self-assembled structures were also investigated for an extended duration of Gly deposition using isotope labeling.

6.
Langmuir ; 38(50): 15516-15525, 2022 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-36469018

RESUMO

The polymerization of amino acids (AAs) to peptides on oxide surfaces has attracted interest owing to its high importance in biotechnology, prebiotic chemistry, and origin of life theories. However, its mechanism is still poorly understood. We tried to elucidate the reactivity of glycine (Gly) from the vapor phase on the surface of amorphous silica under controlled atmosphere at 160 °C. Infrared (IR) spectroscopy reveals that Gly functionalizes the silica surface through the formation of ester species, which represent, together with the weakly interacting silanols, crucial elements for monomers activation and polymerization. Once activated, ß-turns start to form as initiators for the growth of long linear polypeptides (poly-Gly) chains, which elongate into ordered structures containing both ß-sheet and helical conformations. The work also points to the role of water vapor in the formation of further self-assembled ß-sheet structures that are highly resistant to hydrolysis.


Assuntos
Peptídeos , Dióxido de Silício , Dióxido de Silício/química , Peptídeos/química , Minerais , Aminoácidos/química , Glicina/química
7.
Life (Basel) ; 12(11)2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36362844

RESUMO

The role of minerals in the chemical evolution of RNA molecules is an important issue when considering the early stage of the Hadean Earth. In particular, the interaction between functional ribozymes and ancient minerals under simulated primitive conditions is a recent research focus. We are currently attempting to design a primitive RNA metabolic network which would function with minerals, and believe that the simulated chemical network of RNA molecules would be useful for evaluation of the chemical evolution from a simple RNA mixture to an RNA-based life-like system. First, we measured the binding interactions of oligonucleotides with four types of minerals; Aerosil silica, zirconium silicate, sepiolite, and montmorillonite. Oligonucleotides bound zirconium silicate and montmorillonite in the presence of MgCl2, and bound sepiolite both in the presence and absence of MgCl2, but they did not bind Aerosil. Based on the binding behavior, we attempted the self-cleavage reaction of the hammerhead ribozyme from an avocado viroid. This reaction was strongly inhibited by zirconium silicate, a compound regarded as mineral evidence for the existence of water. The present study suggests that the chemical evolution of functional RNA molecules requires specific conformational binding, resulting in efficient ribozyme function as well as zirconium silicate for the chemical evolution of biomolecules.

8.
Sci Rep ; 12(1): 19178, 2022 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-36357418

RESUMO

A large set of nucleobases and amino acids is found in meteorites, implying that several chemical reservoirs are present in the solar system. The "geochemical continuity" hypothesis explores how protometabolic paths developed from so-called "bricks" in an enzyme-free prebiotic world and how they affected the origins of life. In the living cell, the second step of synthesizing uridine and cytidine RNA monomers is a carbamoyl transfer from a carbamoyl donor to aspartic acid. Here we compare two enzyme-free scenarios: aqueous and mineral surface scenarios in a thermal range up to 250 °C. Both processes could have happened in ponds under open atmosphere on the primeval Earth. Carbamoylation of aspartic acid with cyanate in aqueous solutions at 25 °C gives high N-carbamoyl aspartic acid yields within 16 h. It is important to stress that, while various molecules could be efficient carbamoylating agents according to thermodynamics, kinetics plays a determining role in selecting prebiotically possible pathways.


Assuntos
Ácido Aspártico , Uracila , Uracila/química , Carbamilação de Proteínas , Lagoas , Esqueleto , Origem da Vida
9.
BMC Cancer ; 22(1): 1192, 2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36402993

RESUMO

BACKGROUND: The real-world experience of Swiss chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs) is largely unknown, in particular with regard to achievement of response per European Leukemia Net (ELN) criteria and adherence to ELN recommendations. METHODS: This was a retrospective, non-interventional, multicenter chart review of patients with newly diagnosed CML who had received first-line TKI and were solely treated with TKIs between 2010 and 2015, with a minimum follow-up of 18 months, at six Swiss hospitals. Effectiveness was evaluated according to ELN 2013 milestone achievements at 3, 6, 12 and 18 months, and at last follow-up. RESULTS: Data from 63 patients (56% men; median age at diagnosis 55 years) were collected (first-line imatinib [n = 27], nilotinib [n = 27], dasatinib [n = 8], or ponatinib [n = 1]). TKI switches (49 times) and dosing changes (165 times) due to intolerance or insufficient response were frequent. Compared with patients receiving first-line imatinib, a higher proportion of patients receiving first-line nilotinib or dasatinib achieved optimal response at all timepoints, irrespective of subsequent TKI therapy, and a higher proportion of patients treated with first-line nilotinib and dasatinib reached deep molecular response (BCR-ABL1IS ≤ 0.01%) at 18 months (42 and 38%, respectively, versus 27%). Patients who received nilotinib or dasatinib switched therapies less frequently than patients treated with imatinib, irrespective of subsequent TKI therapy. CONCLUSIONS: Although patient numbers were small, this real-world evidence study with patients with CML confirms that ELN guidelines are generally implemented in Swiss clinical practice, with a large proportion of patients achieving ELN 2013 milestones. While TKI use involved all inhibitors approved at the time of the study, an unexpectedly high number of TKI therapy switches suggests a clear difference in TKI use between registration trials and clinical practice.


Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva , Inibidores de Proteínas Quinases , Humanos , Masculino , Pessoa de Meia-Idade , Feminino , Mesilato de Imatinib/uso terapêutico , Dasatinibe/uso terapêutico , Estudos Retrospectivos , Suíça/epidemiologia , Inibidores de Proteínas Quinases/uso terapêutico , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Doença Crônica
10.
Life (Basel) ; 12(8)2022 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-36013404

RESUMO

The RNA world hypothesis suggests that chemical networks consisting of functional RNA molecules could have constructed a primitive life-like system leading a first living system. The chemical evolution scenario of RNA molecules should be consistent with the Hadean Earth environment. We have demonstrated the importance of the environment at both high temperature and high pressure, using different types of hydrothermal flow reactor systems and high-pressure equipment. In the present study, we have attempted to develop an alternative easy-to-implement method for high-pressure measurements and demonstrate that the system is applicable as an efficient research tool for high-pressure experiments at pressures up to 30 MPa. We demonstrate the usefulness of the system by detecting the high-pressure influence for the self-cleavage of avocado hammerhead ribozyme (ASBVd(-):HHR) at 45-65 °C. A kinetic analysis of the high-pressure behavior of ASBVd(-):HHR shows that the ribozyme is active at 30 MPa and its activity is sensitive to pressures between 0.1-30 MPa. The surprising finding that such a short ribozyme is effective for self-cleavage at a high pressure suggests the importance of pressure as a factor for selection of adaptable RNA molecules towards an RNA-based life-like system in the Hadean Earth environment deep in the ocean.

11.
Langmuir ; 38(26): 8038-8053, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35737817

RESUMO

Leucine on silica constitutes an interesting system from the point of view of origins of life studies since leucine coadsorbed on SiO2 together with glutamic acid can give rise to rather long linear polypeptides upon activation. It is also an ideal system to test methods of molecular characterization of biomolecules deposited on mineral surfaces since it combines a small-scale model of peptides and proteins, which are among the most important components of biodevices, with one of the most widely used inorganic materials. We have deposited l-leucine on a high surface fumed silica in the submonolayer range and characterized it by a multipronged approach including macroscopic information (thermogravimetry, X-ray diffraction), in situ spectroscopic methods (IR, multinuclear solid-state NMR including single-pulse and CP-MAS, 2-D HETCOR), and molecular modeling by density functional theory (DFT), including calculation of NMR parameters. Specific information can be obtained on the adsorption and interaction mechanism. Leucine is rather strongly adsorbed without any covalent bonds, through the formation of a specific lattice of H-bonds that often involve coadsorbed water molecules. Its state is indeed strongly dependent on the drying procedure: insufficient drying results in liquid-like surroundings for the leucine functional groups, while vacuum drying only retains a limited number of waters (of the order of 5 per leucine molecule). The most stable models have zwitterionic leucine interacting directly with surface silanols through their ammonium group, while the carboxylate interacts through bridging waters. Experimental NMR chemical shifts are satisfactorily predicted for these models, and leucine can be viewed as a probe for specific groups of surface sites known as silanol nests.


Assuntos
Dióxido de Silício , Água , Adsorção , Leucina/química , Espectroscopia de Ressonância Magnética/métodos , Peptídeos/química , Dióxido de Silício/química , Água/química
12.
Sci Rep ; 11(1): 19356, 2021 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-34588537

RESUMO

The first step of pyrimidine synthesis along the orotate pathway is studied to test the hypothesis of geochemical continuity of protometabolic pathways at the origins of life. Carbamoyl phosphate (CP) is the first high-energy building block that intervenes in the in vivo synthesis of the uracil ring of UMP. Thus, the likelihood of its occurrence in prebiotic conditions is investigated herein. The evolution of carbamoyl phosphate in water and in ammonia aqueous solutions without enzymes was characterised using ATR-IR, 31P and 13C spectroscopies. Carbamoyl phosphate initially appears stable in water at ambient conditions before transforming to cyanate and carbamate/hydrogenocarbonate species within a matter of hours. Cyanate, less labile than CP, remains a potential carbamoylating agent. In the presence of ammonia, CP decomposition occurs more rapidly and generates urea. We conclude that CP is not a likely prebiotic reagent by itself. Alternatively, cyanate and urea may be more promising substitutes for CP, because they are both "energy-rich" (high free enthalpy molecules in aqueous solutions) and kinetically inert regarding hydrolysis. Energy-rich inorganic molecules such as trimetaphosphate or phosphoramidates were also explored for their suitability as sources of carbamoyl phosphate. Although these species did not generate CP or other carbamoylating agents, they exhibited energy transduction, specifically the formation of high-energy P-N bonds. Future efforts should aim to evaluate the role of carbamoylating agents in aspartate carbamoylation, which is the following reaction in the orotate pathway.

13.
Data Brief ; 34: 106630, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33409341

RESUMO

The data presented here concern the photophysical characterization of luminescent MCM-41 nanoparticles doped with 3-hydroxyflavone and 7-hydroxyflavone, two fluorescent flavonoids. UV-Vis and fluorescence spectra obtained on freshly-prepared samples and aged (2 months exposed to air) samples are shown. The effect of light exposure is also studied. In parallel, experiments have been carried out in acetonitrile solutions of the two flavonoids as a term of comparison. Time-dependent density functional theory calculations have also been used to simulate UV-Vis and emission spectra of different species for both flavonoids (neutral molecule, tautomers, cationic and anionic forms), taking into account the effect of the surrounding medium (solvent). Density functional theory calculations of vibrational spectra (IR, Raman) of neutral and tautomeric species of 3HF and 7HF are also provided.

14.
Rev Med Suisse ; 16(705): 1613-1617, 2020 Sep 09.
Artigo em Francês | MEDLINE | ID: mdl-32914592

RESUMO

Differential blood count is an excellent complementary test to complete blood count, which allows analysis of the white cell differentiation and their morphologic particularity. As the tendency currently leads to targeted laboratory analysis, differential blood count provides a diagnostic and prognostic value in many clinical situations, notably in patients with an infection. Based on clinical cases, this article reviews the different white blood cell lines to provide key points for interpretation of qualitative and quantitative anomalies encountered in the daily hospital practice.


La formule sanguine complète est un excellent complément à la formule sanguine simple, permettant une analyse de la répartition des leucocytes, ainsi que de leurs particularités morphologiques. Alors que la tendance est aux analyses de laboratoire ciblées, la répartition garde une utilité diagnostique et pronostique dans de nombreuses situations cliniques, notamment dans un contexte infectieux. À travers la présentation de cas, cet article passe en revue les différentes lignées leucocytaires afin de donner quel ques clefs d'interprétation d'anomalies qualitatives et quantitatives pouvant être rencontrées dans la pratique hospitalière quotidienne.


Assuntos
Contagem de Leucócitos , Leucócitos/citologia , Técnicas de Laboratório Clínico , Hospitais , Humanos , Prognóstico
15.
Biomacromolecules ; 20(12): 4522-4534, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31710810

RESUMO

A comprehensive understanding of the mechanism by which type I collagen (Col) interacts with hydroxyapatite nanoparticles (Hap NPs) in aqueous solutions is a pivotal step for guiding the design of biologically relevant nanocomposites with controlled hierarchical structure. In this paper we use a variety of Hap NPs differing by their shape (rod vs platelet) and their size (∼30 vs ∼130 nm) and investigate their mechanism(s) of interaction with collagen. The addition of collagen to the Hap suspensions induces different effects that strongly depend on the nanoparticle type. Interestingly, the use of small rods, typically with ∼30 nm of length (R30), leads to the formation of assembled collagen fibrils decorated with Hap nanocrystals which, in turn, self-assemble progressively to form larger fibrillar Hap-Col composite. The crystals decorating collagen provide "intrinsic" negative charges to the fibrillar objects that allow their incorporation in three-dimensional structure using layer-by-layer (LbL) assembly. This offers a straightforward way to construct a collagen-based hybrid material with well-defined hierarchy under near-physiological conditions. In situ, QCM-D monitoring revealed the buildup of soft and highly hydrated hybrid (PAH/R30-Col)n multilayers for which the mechanism of growth was very different from that observed for polyelectrolytes and nanoparticles without collagen (PAH/R30). The LbL assembly of crystal-decorated collagen yields a hierarchical nanostructured film whose thickness and roughness can be modulated by the addition of salt and incorporate fibrillar objects of about 400 nm in width and few micrometers in length, as probed by AFM. The approach described in this work provides a relevant way to better control the (supra)molecular assembly of Col and Hap NPs with the perspective of developing hierarchical Hap-Col nanocomposites with tuned properties for various biomedical applications.


Assuntos
Colágeno/química , Durapatita/química , Nanocompostos/química , Nanopartículas/química
16.
Chemistry ; 25(5): 1275-1285, 2019 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-30284764

RESUMO

Evidence for the formation of linear oligopeptides with nonrandom sequences from mixtures of amino acids coadsorbed on silica and submitted to a simple thermal activation is presented. The amino acid couples (glutamic acid+leucine) and (aspartic acid+valine) were deposited on a fumed silica and submitted to a single heating step at moderate temperature. The evolution of the systems was characterized by X-ray diffraction, infrared spectroscopy, thermosgravimetric analysis, HPLC, and electrospray ionization mass spectrometry (ESI-MS). Evidence for the formation of amide bonds was found in all systems studied. While the products of single amino acids activation on silica could be considered as evolutionary dead ends, (glutamic acid+leucine) and, at to some extent, (aspartic acid+valine) gave rise to the high yield formation of linear peptides up to the hexamers. Oligopeptides of such length have not been observed before in surface polymerization scenarios (unless the amino acids had been deposited by chemical vapor deposition, which is not realistic in a prebiotic environment). Furthermore, not all possible amino acid sequences were present in the activation products, which is indicative of polymerization selectivity. These results are promising for origins of life studies because they suggest the emergence of nonrandom biopolymers in a simple prebiotic scenario.


Assuntos
Aminoácidos/química , Peptídeos/química , Prebióticos/análise , Dióxido de Silício/química , Ácido Aspártico , Ácido Glutâmico , Leucina/química , Polimerização , Espectrometria de Massas por Ionização por Electrospray , Termogravimetria , Valina
17.
J Phys Chem Lett ; 9(17): 4981-4987, 2018 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-30107125

RESUMO

Understanding the mechanism of spontaneous formation of ribonucleotides under realistic prebiotic conditions is a key open issue of origins-of-life research. In cells, de novo and salvage nucleotide enzymatic synthesis combines 5-phospho-α-d-ribose-1-diphosphate (α-PRPP) and nucleobases. Interestingly, these reactants are also known as prebiotically plausible compounds. Combining ab initio molecular dynamics simulations with recently developed reaction exploration and enhanced sampling methods, we show that nucleobases and α-PRPP should spontaneously combine, under mild hydrothermal conditions, with an exothermic reaction and a facile mechanism, forming both purine and pyrimidine ribonucleotides. Surprisingly, this mechanism is very similar to the biological one and yields ribonucleotides with the same anomeric carbon chirality as in biological systems. Mass spectrometry experiments performed on solutions of adenine and PRPP in similar conditions support the formation of AMP. These results suggest that natural selection might have optimized, through enzymes, a pre-existing ribonucleotide formation mechanism, carrying it forward to modern life forms.


Assuntos
Simulação de Dinâmica Molecular , Teoria Quântica , RNA/química , Ribonucleotídeos/síntese química , Conformação de Ácido Nucleico , Prebióticos , Ribonucleotídeos/química
18.
Haematologica ; 103(12): 2033-2039, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30026341

RESUMO

In standard-risk acute promyelocytic leukemia, recent results have shown that all-trans retinoic acid plus arsenic trioxide combinations are at least as effective as classical all-trans retinoic acid plus anthracycline-based chemotherapy while being less myelosuppressive. However, the role of frontline arsenic trioxide is less clear in higher-risk acute promyelocytic leukemia, and access to arsenic remains limited for front-line treatment of standard-risk acute promyelocytic leukemia in many countries. In this randomized trial, we compared arsenic, all-trans retinoic acid and the "classical" cytarabine for consolidation treatment (after all-trans retinoic acid and chemotherapy induction treatment) in standard-risk acute promyelocytic leukemia, and evaluated the addition of arsenic during consolidation in higher-risk disease. Patients with newly diagnosed acute promyelocytic leukemia with a white blood cell count <10x109/L, after an induction treatment consisting of all-trans retinoic acid plus idarubicin and cytarabine, received consolidation chemotherapy with idarubicin and cytarabine, arsenic or all-trans retinoic acid. Patients with a white blood cell count >10x109/L received consolidation chemotherapy with or without arsenic. Overall, 795 patients with acute promyelocytic leukemia were enrolled in this trial. Among those with standard-risk acute promyelocytic leukemia (n=581), the 5-year event-free survival rates from randomization were 88.7%, 95.7% and 85.4% in the cytarabine, arsenic and all-trans retinoic acid consolidation groups, respectively (P=0.0067), and the 5-year cumulative incidences of relapse were was 5.5%, 0% and 8.2%. (P=0.001). Among those with higher-risk acute promyelocytic leukemia (n=214), the 5-year event-free survival rates were 85.5% and 92.1% (P=0.38) in the chemotherapy and chemotherapy plus arsenic groups, respectively, and the corresponding 5-year cumulative incidences of relapse were 4.6% and 3.5% (P=0.99). Given the prolonged myelosuppression that occurred in the chemotherapy plus arsenic arm, a protocol amendment excluded cytarabine during consolidation cycles in the chemotherapy plus arsenic group, resulting in no increase in relapse. Our results therefore advocate systematic introduction of arsenic in the first-line treatment of acute promyelocytic leukemia, but probably not concomitantly with intensive chemotherapy, a situation in which we found myelosuppression to be significant. (ClinicalTrials.gov Identifier: NCT00378365).


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Leucemia Promielocítica Aguda/tratamento farmacológico , Adulto , Antraciclinas/administração & dosagem , Trióxido de Arsênio/administração & dosagem , Bélgica , Intervalo Livre de Doença , Feminino , França , Humanos , Leucemia Promielocítica Aguda/diagnóstico , Masculino , Pessoa de Meia-Idade , Suíça , Resultado do Tratamento , Tretinoína/administração & dosagem
19.
Angew Chem Int Ed Engl ; 56(27): 7920-7923, 2017 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-28558156

RESUMO

In this contribution, we report the formation under prebiotic conditions of phosphoribosyl pyrophosphate (PRPP) as a molecular precursor in the one-pot synthesis of a canonical nucleotide, namely adenosine monophosphate (AMP) from its building blocks (KH2 PO4 or Pi , adenine, and d-ribose), on a fumed silica surface. The on-the-rocks approach has been successfully applied to the simultaneous phosphorylation and glycosylation of ribose. The one-pot formation mechanism of AMP involves a two-step pathway via an activated intermediate, namely PRPP, obtained by multiple ribose phosphorylations upon mild thermal activation.

20.
Langmuir ; 33(18): 4414-4425, 2017 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-28380299

RESUMO

Herein, we report the coating of a surface with a random nanoscale topography with a lipid film formed by an anchoring stearic acid (SA) monolayer and phospholipid (DPPC) layers. For this purpose, different procedures were used for phospholipid coating, including adsorption from solution, drop deposition, and spin-coating. Our results reveal that the morphology of the obtained lipid films is strongly influenced by the topography of the underlying substrate but also impacted by other factors, including the coating procedure and surface wettability (modulated by the presence of SA). These coated surfaces showed a remarkable antifouling behavior toward proteins, with different yields of repellency (Yrp) depending on the amount/organization of DPPC on the nanostructured substrate. The interaction between the proteins and phospholipids involves a partial detachement of the film. The use of characterization techniques with different charcateristics (accuracy, selectivity, analysis depth) did not reveal any obvious vertical heterogenity of the probed interface, indicating that the lipid film acts as a nonfouling coating on the whole surface, including the outermost part (nanoprotrusions) and deeper regions (valleys).


Assuntos
Proteínas/química , Adsorção , Nanoestruturas , Fosfolipídeos , Propriedades de Superfície
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