Publications by authors named "Quist D"

Rift Valley fever (RVF) is a mosquito-borne viral disease that primarily affects animals, especially ruminants, but has the capacity to infect humans and result in outbreaks. Infection with the causative agent, RVF virus (RVFV), causes severe disease in domestic animals, especially sheep, resulting in fever, anorexia, immobility, abortion, and high morbidity and mortality rates in neonate animals. Humans become infected through exposure to infected animals and, less frequently, directly via a mosquito bite.

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Article Synopsis
  • - Pediatric high-grade gliomas often have gene fusions with receptor tyrosine kinase genes, such as NTRK, leading to high initial responses to treatment but eventual recurrence due to new mutations.
  • - Researchers created mouse models of gliomas driven by NTRK fusions to study how different genetic variations influence tumor characteristics and aggressiveness.
  • - While TRK kinase inhibitors improve survival rates in these mice, they do not eliminate the tumors, with recurrence likely due to ERK activation; combining these inhibitors with MEK inhibitors might enhance treatment effectiveness.
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Pediatric-type high-grade gliomas frequently harbor gene fusions involving receptor tyrosine kinase genes, including neurotrophic tyrosine kinase receptor (NTRK) fusions. Clinically, these tumors show high initial response rates to tyrosine kinase inhibition but ultimately recur due to the accumulation of additional resistance-conferring mutations. Here, we developed a series of genetically engineered mouse models of treatment-naïve and -experienced NTRK1/2/3 fusion-driven gliomas.

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The dioxygen reactivity of a series of TMPA-based copper(I) complexes (TMPA=tris(2-pyridylmethyl)amine), with and without secondary-coordination-sphere hydrogen-bonding moieties, was studied at -135 °C in 2-methyltetrahydrofuran (MeTHF). Kinetic stabilization of the H-bonded [( TMPA)Cu (O )] cupric superoxide species was achieved, and they were characterized by resonance Raman (rR) spectroscopy. The structures and physical properties of [( TMPA)Cu (N )] azido analogues were compared, and the O reactivity of ligand-Cu complexes when an H-bonding moiety is replaced by a methyl group was contrasted.

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Secondary coordination sphere interactions are critical in facilitating the formation, stabilization, and enhanced reactivity of high-valent oxidants required for essential biochemical processes. Herein, we compare the C-H bond oxidizing capabilities of spectroscopically characterized synthetic heme iron(IV) oxo complexes, FCmpd-II (F = tetrakis(2,6-difluorophenyl)porphyrinate), and a 2,6-lutidinium triflate (LutH) Lewis acid adduct involving ferryl O-atom hydrogen-bonding, FCmpd-II(LutH). Second-order rate constants utilizing C-H and C-D substrates were obtained by UV-vis spectroscopic monitoring, while products were characterized and quantified by EPR spectroscopy and gas chromatography (GC).

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A superoxide-bridged dicopper(II) complex, [Cu(XYLO)(O)] () (XYLO = binucleating -xylyl derivative with a bridging phenolate ligand donor and two bis(2-{2-pyridyl}ethyl)amine arms), was generated from chemical oxidation of the peroxide-bridged dicopper(II) complex [Cu(XYLO)(O)] (), using ferrocenium (Fc) derivatives, in 2-methyltetrahydrofuran (MeTHF) at -125 °C. Using MeFc, a ⇆ equilibrium was established, allowing for calculation of the reduction potential of as -0.525 ± 0.

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Article Synopsis
  • The study explores how hydrogen bonding plays a role in the reduction of dioxygen by heme-copper oxidases, focusing on the active site's cleavage of the O-O bond.
  • Sixteen synthetic heme-(μ-O)-Cu(TMPA) complexes were created, showing that derivatives with amino pendants preferentially form H-bonds with the copper-bound peroxide, evidenced by UV-vis spectroscopy and resonance Raman spectroscopy.
  • The findings highlight that optimal H-bonding for O-O bond activation occurs with two amino groups, providing insights into the chemistry of O-O cleavage and supporting previous computational and structural studies regarding interstitial H-bonding.
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Investigations of small molecule copper-dioxygen chemistry can and have provided fundamental insights into enzymatic processes (e.g., copper metalloenzyme dioxygen binding geometries and their associated spectroscopy and substrate reactivity).

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Synthetic peroxo-bridged high-spin (HS) heme-(μ-η:η-O)-Cu(L) complexes incorporating (as part of the copper ligand) intramolecular hydrogen-bond (H-bond) capabilities and/or steric effects are herein demonstrated to affect the complex's electronic and geometric structure, notably impacting the spin state. An H-bonding interaction with the peroxo core favors a low-spin (LS) heme-(μ-η:η-O)-Cu(L) structure, resulting in a reversible temperature-dependent interconversion of spin state (5 coordinate HS to 6 coordinate LS). The LS state dominates at low temperatures, even in the absence of a strong trans-axial heme ligand.

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Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H/4e reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements.

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Direct experimental determination of redox properties of superoxo (O ) and peroxo (O ) embedded in dicopper complexes bearing an unsymmetrical binucleating ligand was achieved using cryo-electrochemistry and cryo-spectroelectrochemistry in dichloromethane. Cyclic voltammetry for dicopper(I) (1 ) oxidation to a Cu Cu mixed-valent species (1 ) under inert atmosphere at 193 K reveals slow heterogeneous electron-transfer kinetics, indicative of a large reorganization energy. Oxygenation of the dicuprous complex 1 gives the bridged peroxo dicopper(II) species 3 , which is reversibly oxidized to the superoxo complex 2 at E =0.

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Nature uses dioxygen as a key oxidant in the transformation of biomolecules. Among the enzymes that are utilized for these reactions are copper-containing metalloenzymes, which are responsible for important biological functions such as the regulation of neurotransmitters, dioxygen transport, and cellular respiration. Enzymatic and model system studies work in tandem in order to gain an understanding of the fundamental reductive activation of dioxygen by copper complexes.

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Primary copper(I)-dioxygen (O) adducts, cupric-superoxide complexes, have been proposed intermediates in copper-containing dioxygen-activating monooxygenase and oxidase enzymes. Here, mechanisms of C-H activation by reactive copper-(di)oxygen intermediates are discussed, with an emphasis on cupric-superoxide species. Over the past 25 years, many synthetically derived cupric-superoxide model complexes have been reported.

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Between the 24th of June and the 6th of July 2005, nine men came to Fort-de-France emergency department (Martinique, French West Indies) with more or less pronounced pulmonary symptoms associated in two cases with skin lesions. Three weeks before these nine men performed work in a deserted house. The diagnosis of histoplasmosis was based on pulmonary sample mycological analysis (direct examination and culture), molecular biology and serological tests.

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Introduction: Chondroid syringoma (CS) is a rare cutaneous tumor characterized by mixte epithelial and mesenchymal component. The confident histological diagnosis can be obtained by immuno-histochemistry study. Here we present 10 new cases with their clinico-hystological characteristics.

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Among the opportunistic mycoses that are emerging in patients with immunosuppression or severe underlying illness, many isolates lack of characteristic sporulation and until recently could not be identified. Clinical signs are mostly nonspecific and therefore such infections have often been disregarded. In the present paper we describe a novel, nonsporulating fungal species causing subcutaneous phaeohyphomycosis in two patients of different origin.

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Mycetoma is a chronic granulomatous infection that is difficult to treat, notably when due to fungi such as Scedosporium apiospermum. Recent antifungal agents could be an option, but cases are rarely reported, and none with posaconazole. Paradoxical responses, defined as initial clinical worsening despite appropriate treatment, are common in tuberculosis but rare in deep mycoses in non-immunocompromised hosts.

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Background: We report a case of pyoderma gangrenosum (PG) associated with a complication comprising ascending aortic dissection (neutrophilic aortitis) in a setting of rheumatoid arthritis (RA).

Patients And Methods: A 79-year-old female patient was hospitalized in late 2009 for vegetating PG. Treatment with general steroids followed by colchicine and topical steroids resulted in complete healing of skin lesions.

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Background: Calciphylaxis is a rare and severe disease with an annual incidence of around 1 % in dialysis patients. The main study aim was to determine its incidence in Martinique, where there is a significant population of patients on dialysis.

Patients And Methods: All patients diagnosed with calciphylaxis between 2006 and 2012 and living in Martinique were included, retrospectively.

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Genetic mutations must be avoided during the production and use of seeds. In the European Union (EU), Directive 2001/18/EC requires any DNA construct introduced via transformation to be stable. Establishing genetic stability is critical for the approval of genetically modified organisms (GMOs).

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Phaeohyphomycosis is a group of superficial and deep infections due to dematiaceous fungi. They are most common in tropical environments, especially in immunocompromised hosts. We describe the first case of phaeohyphomycosis due to Pleurostoma ootheca in a kidney transplant recipient in Martinique (French West Indies).

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A tripodal ligand based on 2-hydroxypyridine is presented. Cu-Cl adducts of H3thpa with Cu(I) and Cu(II) provide complexes featuring highly directed, intramolecular hydrogen-bonding interactions. An upper limit for the hydrogen-bonding free energy to Cu(I)-Cl was estimated at ∼18 kcal/mol.

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The parasite responsible for autochthonous cutaneous leishmaniasis in Martinique island (French West Indies) was first isolated in 1995; its taxonomical position was established only in 2002, but it remained unnamed. In the present paper, the authors name this parasite Leishmania (Leishmania) martiniquensis Desbois, Pratlong & Dedet n. sp.

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