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1.
J Clin Nurs ; 32(13-14): 3831-3839, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35995762

RESUMEN

AIM: To construct and validate a postoperative hypothermia prediction model for patients undergoing joint replacement surgery. BACKGROUND: Postoperative hypothermia is one of the harmful perioperative complications in patients undergoing joint replacement surgery. The previous studies mainly focused on intraoperative hypothermia prediction models. The prediction model for postoperative hypothermia in patients with joint replacement surgery was understudied. DESIGN: Cohort study. METHODS: We collected data from 503 participants undergoing joint replacement surgery in a tertiary hospital from January 2019 to December 2021. Of those, 404 cases were assigned to the modelling and 99 to the validation groups. Logistic regression was used to construct the model. The AUC was used to test the predictive effect of the model. Finally, 99 cases were used to verify the application effect of the model. A TRIPOD checklist was used to guide the reporting of this study. RESULTS: The factors entered into the prediction model were age, intraoperative hypothermia, BMI, heat preservation measures and platelet (PLT). The model was constructed as follows: Logit (P) = .537 + 3.669 × 1 (intraoperative hypothermia) + .030 × age - .289 × BMI + 2.857 × 1 (intraoperative insulation measures) + .003 × PLT. Hosmer-Lemeshow test, p = .608, the area under the receiver operating characteristic curve (AUC) was .861. The Youden index was .530, the sensitivity was .599 and the specificity was .93. The incidence of postoperative hypothermia in the modelling group was 42.93% (173/404), and that in the verification group was 43.43% (43/99), χ2 = .012, p = .912. The correct practical application rate was 87.88%. This model has a good application effect. CONCLUSION: The current prediction model provided a reference for clinical screening of patients with high-risk hypothermia after joint replacement surgery. RELEVANCE TO CLINICAL PRACTICE: Clinical nurses can use the developed prediction model to predict the occurrence of postoperative hypothermia and provide a reference for the preventive measure.


Asunto(s)
Artroplastia de Reemplazo , Hipotermia , Humanos , Hipotermia/etiología , Hipotermia/prevención & control , Estudios de Cohortes , Modelos Logísticos , Curva ROC , Artroplastia de Reemplazo/efectos adversos , Estudios Retrospectivos , Factores de Riesgo , Complicaciones Posoperatorias/epidemiología
2.
Angew Chem Int Ed Engl ; 61(18): e202202017, 2022 04 25.
Artículo en Inglés | MEDLINE | ID: mdl-35178852

RESUMEN

Direct deoxygenation of long-chain fatty acids can produce both saturated alkanes (Cn H2n+2 ) and unsaturated olefins (Cn H2n ). However, the selectivity for the production of olefins via the decarbonylation route is relatively low because of the more favorable decarboxylation pathway. We present an atomically ordered intermetallic PtZn alloy on carbon catalyst (PtZn/C) with a record-high total selectivity (97 %) for undecane (C11 H24 ) and undecene (C11 H22 ) in the deoxygenation of lauric acid (C12 H24 O2 ). Interestingly, the selectivity for C11 H22 is as high as 67.0 % on PtZn/C, which is significantly higher than that of 27.5 % obtained on the Pt/C counterpart under the same reaction conditions. Characterization and theoretical calculation results reveal that the intermetallic PtZn alloy not only inhibits the decarboxylation route by increasing the energy barrier of -COO* cleavage, but also facilitates the decarbonylation route by decreasing CO desorption energy, and therefore the major product is switched from alkanes to olefins.


Asunto(s)
Ácidos Grasos , Platino (Metal) , Alcanos , Alquenos , Aleaciones , Zinc
3.
Nature ; 525(7567): 129-33, 2015 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-26308899

RESUMEN

The GGGGCC (G4C2) repeat expansion in a noncoding region of C9orf72 is the most common cause of sporadic and familial forms of amyotrophic lateral sclerosis and frontotemporal dementia. The basis for pathogenesis is unknown. To elucidate the consequences of G4C2 repeat expansion in a tractable genetic system, we generated transgenic fly lines expressing 8, 28 or 58 G4C2-repeat-containing transcripts that do not have a translation start site (AUG) but contain an open-reading frame for green fluorescent protein to detect repeat-associated non-AUG (RAN) translation. We show that these transgenic animals display dosage-dependent, repeat-length-dependent degeneration in neuronal tissues and RAN translation of dipeptide repeat (DPR) proteins, as observed in patients with C9orf72-related disease. This model was used in a large-scale, unbiased genetic screen, ultimately leading to the identification of 18 genetic modifiers that encode components of the nuclear pore complex (NPC), as well as the machinery that coordinates the export of nuclear RNA and the import of nuclear proteins. Consistent with these results, we found morphological abnormalities in the architecture of the nuclear envelope in cells expressing expanded G4C2 repeats in vitro and in vivo. Moreover, we identified a substantial defect in RNA export resulting in retention of RNA in the nuclei of Drosophila cells expressing expanded G4C2 repeats and also in mammalian cells, including aged induced pluripotent stem-cell-derived neurons from patients with C9orf72-related disease. These studies show that a primary consequence of G4C2 repeat expansion is the compromise of nucleocytoplasmic transport through the nuclear pore, revealing a novel mechanism of neurodegeneration.


Asunto(s)
Transporte Activo de Núcleo Celular/genética , Expansión de las Repeticiones de ADN/genética , Drosophila melanogaster/citología , Drosophila melanogaster/metabolismo , Sistemas de Lectura Abierta/genética , Proteínas/genética , Transporte de ARN/genética , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/patología , Animales , Animales Modificados Genéticamente , Proteína C9orf72 , Drosophila melanogaster/genética , Ojo/metabolismo , Femenino , Demencia Frontotemporal/genética , Demencia Frontotemporal/patología , Células HeLa , Humanos , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Masculino , Músculos/citología , Músculos/metabolismo , Neuronas/citología , Neuronas/metabolismo , Poro Nuclear/genética , Poro Nuclear/metabolismo , Poro Nuclear/patología , Fenotipo , Biosíntesis de Proteínas , ARN/genética , ARN/metabolismo , Glándulas Salivales/citología , Glándulas Salivales/metabolismo , Glándulas Salivales/patología
4.
Mol Cell ; 52(2): 264-71, 2013 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-24095276

RESUMEN

Phagophore maturation is a key step in the macroautophagy pathway, which is critical in many important physiological and pathological processes. Here we identified Drosophila N-ethylmaleimide-sensitive fusion protein 2 (dNSF2) and soluble NSF attachment protein (Snap) as strong genetic modifiers of mutant CHMP2B, an ESCRT-III component that causes frontotemporal dementia and autophagosome accumulation. Among several SNAP receptor (SNARE) genes, Drosophila syntaxin 13 (syx13) exhibited a strong genetic interaction with mutant CHMP2B. Knockdown of syntaxin 13 (STX13) or its binding partner Vti1a in mammalian cells caused LC3-positive puncta to accumulate and blocks autophagic flux. STX13 was present on LC3-positive phagophores induced by rapamycin and was highly enriched on multilamellar structures induced by dysfunctional ESCRT-III. Loss of STX13 also caused the accumulation of Atg5-positive puncta and the formation of multilamellar structures. These results suggest that STX13 is a genetic modifier of ESCRT-III dysfunction and participates in the maturation of phagophores into closed autophagosomes.


Asunto(s)
Autofagia , Proteínas de Drosophila/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Fagosomas/metabolismo , Proteínas Qa-SNARE/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Animales , Western Blotting , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Anomalías del Ojo/genética , Anomalías del Ojo/metabolismo , Demencia Frontotemporal/genética , Demencia Frontotemporal/metabolismo , Células HEK293 , Células HeLa , Humanos , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Microscopía Confocal , Microscopía Inmunoelectrónica , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Mutación , Proteínas Sensibles a N-Etilmaleimida/genética , Proteínas Sensibles a N-Etilmaleimida/metabolismo , Fagosomas/ultraestructura , Fenotipo , Proteínas Qa-SNARE/genética , Interferencia de ARN , Proteínas de Transporte Vesicular/genética
5.
Angew Chem Int Ed Engl ; 60(50): 26054-26062, 2021 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-34346155

RESUMEN

A single-atom Pt1 /CeO2 catalyst formed by atom trapping (AT, 800 °C in air) shows excellent thermal stability but is inactive for CO oxidation at low temperatures owing to over-stabilization of Pt2+ in a highly symmetric square-planar Pt1 O4 coordination environment. Reductive activation to form Pt nanoparticles (NPs) results in enhanced activity; however, the NPs are easily oxidized, leading to drastic activity loss. Herein we show that tailoring the local environment of isolated Pt2+ by thermal-shock (TS) synthesis leads to a highly active and thermally stable Pt1 /CeO2 catalyst. Ultrafast shockwaves (>1200 °C) in an inert atmosphere induced surface reconstruction of CeO2 to generate Pt single atoms in an asymmetric Pt1 O4 configuration. Owing to this unique coordination, Pt1 δ+ in a partially reduced state dynamically evolves during CO oxidation, resulting in exceptional low-temperature performance. CO oxidation reactivity on the Pt1 /CeO2 _TS catalyst was retained under oxidizing conditions.

7.
Hum Mol Genet ; 22(2): 218-25, 2013 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-23042786

RESUMEN

TDP-43 is an evolutionarily conserved RNA-binding protein currently under intense investigation for its involvement in the molecular pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). TDP-43 is normally localized in the nucleus, but translocated to the cytoplasm in diseased neurons. The endogenous functions of TDP-43 in the nervous system remain poorly understood. Here, we show that the loss of Drosophila TDP-43 (dTDP-43) results in an increased production of sensory bristles and sensory organ precursor (SOP) cells on the notum of some but not all flies. The location of ectopic SOPs varies among mutant flies. The penetrance of this novel phenotype is dependent on the gender and sensitive to environmental influences. A similar SOP phenotype was also observed on the wing and in the embryos. Overexpression of dTDP-43 causes both loss and ectopic production of SOPs. Ectopic expression of ALS-associated mutant human TDP-43 (hTDP-43(M337V) and hTDP-43(Q331K)) produces a less severe SOP phenotype than hTDP-43(WT), indicating a partial loss of function of mutant hTDP-43. In dTDP-43 mutants, miR-9a expression is significantly reduced. Genetic interaction studies further support the notion that dTDP-43 acts through miR-9a to control the precision of SOP specification. These findings reveal a novel role for endogenous TDP-43 in neuronal specification and suggest that the FTD/ALS-associated RNA-binding protein TDP-43 functions to ensure the robustness of genetic control programs.


Asunto(s)
Proteínas de Unión al ADN/metabolismo , Drosophila/genética , Drosophila/metabolismo , Regulación de la Expresión Génica , MicroARNs/genética , Neuronas/metabolismo , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Animales Modificados Genéticamente , Proteínas de Unión al ADN/genética , Epistasis Genética , Femenino , Demencia Frontotemporal/genética , Demencia Frontotemporal/metabolismo , Humanos , Masculino , Mutación , Fenotipo , Factores Sexuales
8.
Acta Neuropathol ; 130(4): 525-35, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26031661

RESUMEN

C9ORF72 repeat expansion is the most common genetic mutation in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Abnormal dipeptide repeat proteins (DPRs) generated from repeat-associated non-AUG (RAN) translation of repeat-containing RNAs are thought to be pathogenic; however, the mechanisms are unknown. Here we report that (GR)80 and (PR)80 are toxic in neuronal and non-neuronal cells in Drosophila. In contrast to reported shorter poly(GR) forms, (GR)80 is mostly localized throughout the cytosol without detectable accumulation in the nucleolus, accompanied by suppression of Notch signaling and cell loss in the wing. Some Notch target genes are also downregulated in brains and iPSC-derived cortical neurons of C9ORF72 patients. Increased Notch expression largely suppressed (GR)80-induced cell loss in the wing. When co-expressed in Drosophila, HeLa cells, or human neurons, (GA)80 recruited (GR)80 into cytoplasmic inclusions, partially decreasing the toxicity of (GR)80 and restoring Notch signaling in Drosophila. Thus, different DPRs have opposing roles in cell loss and we identify the Notch pathway as one of the receptor signaling pathways that might be compromised in C9ORF72 FTD/ALS.


Asunto(s)
Expansión de las Repeticiones de ADN , Cuerpos de Inclusión/metabolismo , Neuronas/metabolismo , Proteínas/metabolismo , Receptores Notch/metabolismo , Anciano , Esclerosis Amiotrófica Lateral/genética , Animales , Animales Modificados Genéticamente , Proteína C9orf72 , Muerte Celular/fisiología , Drosophila , Ojo/metabolismo , Ojo/patología , Demencia Frontotemporal/genética , Células HeLa , Humanos , Células Madre Pluripotentes Inducidas/fisiología , Persona de Mediana Edad , Actividad Motora/fisiología , Neuronas/patología , Proteínas/genética , Receptores Notch/genética , Transducción de Señal , Alas de Animales/patología
9.
PLoS Genet ; 8(2): e1002515, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22347817

RESUMEN

miR-124 is conserved in sequence and neuronal expression across the animal kingdom and is predicted to have hundreds of mRNA targets. Diverse defects in neural development and function were reported from miR-124 antisense studies in vertebrates, but a nematode knockout of mir-124 surprisingly lacked detectable phenotypes. To provide genetic insight from Drosophila, we deleted its single mir-124 locus and found that it is dispensable for gross aspects of neural specification and differentiation. On the other hand, we detected a variety of mutant phenotypes that were rescuable by a mir-124 genomic transgene, including short lifespan, increased dendrite variation, impaired larval locomotion, and aberrant synaptic release at the NMJ. These phenotypes reflect extensive requirements of miR-124 even under optimal culture conditions. Comparison of the transcriptomes of cells from wild-type and mir-124 mutant animals, purified on the basis of mir-124 promoter activity, revealed broad upregulation of direct miR-124 targets. However, in contrast to the proposed mutual exclusion model for miR-124 function, its functional targets were relatively highly expressed in miR-124-expressing cells and were not enriched in genes annotated with epidermal expression. A notable aspect of the direct miR-124 network was coordinate targeting of five positive components in the retrograde BMP signaling pathway, whose activation in neurons increases synaptic release at the NMJ, similar to mir-124 mutants. Derepression of the direct miR-124 target network also had many secondary effects, including over-activity of other post-transcriptional repressors and a net incomplete transition from a neuroblast to a neuronal gene expression signature. Altogether, these studies demonstrate complex consequences of miR-124 loss on neural gene expression and neurophysiology.


Asunto(s)
Drosophila melanogaster/genética , MicroARNs/genética , Mutación/genética , Neurogénesis/genética , Unión Neuromuscular/genética , Animales , Diferenciación Celular/genética , Regulación del Desarrollo de la Expresión Génica , Técnicas de Inactivación de Genes , Locomoción/genética , Unión Neuromuscular/fisiología , Fenotipo , Células Receptoras Sensoriales/patología , Transducción de Señal/genética , Sinapsis/patología , Transcriptoma/genética
10.
Biochim Biophys Acta Mol Basis Dis ; 1869(8): 166841, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37558011

RESUMEN

Mitochondrial dysfunction plays an important role in the pathogenesis of Alzheimer's disease (AD), the most common neurodegenerative disease. Prior studies suggested impaired mitochondrial biogenesis likely contributes to mitochondrial dysfunction in AD. Bezafibrate, a peroxisome proliferator-activated receptor (PPAR) pan-agonist, has been shown to enhance mitochondrial biogenesis and increase oxidative phosphorylation capacity. In the present study, we investigated whether bezafibrate could rescue mitochondrial dysfunction and other AD-related deficits in 5xFAD mice. Bezafibrate was well tolerated by 5xFAD mice. Indeed, it rescued the expression of key mitochondrial proteins as well as mitochondrial dynamics and function in the brain of 5xFAD mice. Importantly, bezafibrate treatment led to significant improvement of cognitive/memory function in 5xFAD mice accompanied by alleviation of amyloid pathology and neuronal loss as well as reduced oxidative stress and neuroinflammation. Overall, this study suggests that bezafibrate improves mitochondrial function, mitigates neuroinflammation and improves cognitive functions in 5xFAD mice, thus supporting the notion that enhancing mitochondrial biogenesis/function is a promising therapeutic strategy for AD.


Asunto(s)
Enfermedad de Alzheimer , Enfermedades Neurodegenerativas , Ratones , Animales , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Bezafibrato/farmacología , Bezafibrato/uso terapéutico , Neuroprotección , Enfermedades Neuroinflamatorias
11.
Acta Neuropathol Commun ; 11(1): 54, 2023 03 31.
Artículo en Inglés | MEDLINE | ID: mdl-37004141

RESUMEN

Loss of synapses is the most robust pathological correlate of Alzheimer's disease (AD)-associated cognitive deficits, although the underlying mechanism remains incompletely understood. Synaptic terminals have abundant mitochondria which play an indispensable role in synaptic function through ATP provision and calcium buffering. Mitochondrial dysfunction is an early and prominent feature in AD which could contribute to synaptic deficits. Here, using electron microscopy, we examined synapses with a focus on mitochondrial deficits in presynaptic axonal terminals and dendritic spines in cortical biopsy samples from clinically diagnosed AD and age-matched non-AD control patients. Synaptic vesicle density within the presynaptic axon terminals was significantly decreased in AD cases which appeared largely due to significantly decreased reserve pool, but there were significantly more presynaptic axons containing enlarged synaptic vesicles or dense core vesicles in AD. Importantly, there was reduced number of mitochondria along with significantly increased damaged mitochondria in the presynapse of AD which correlated with changes in SV density. Mitochondria in the post-synaptic dendritic spines were also enlarged and damaged in the AD biopsy samples. This study provided evidence of presynaptic vesicle loss as synaptic deficits in AD and suggested that mitochondrial dysfunction in both pre- and post-synaptic compartments contribute to synaptic deficits in AD.


Asunto(s)
Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/patología , Sinapsis/metabolismo , Terminales Presinápticos/metabolismo , Mitocondrias/patología , Encéfalo/patología
12.
Nat Commun ; 14(1): 2664, 2023 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-37160890

RESUMEN

Single atoms of platinum group metals on CeO2 represent a potential approach to lower precious metal requirements for automobile exhaust treatment catalysts. Here we show the dynamic evolution of two types of single-atom Pt (Pt1) on CeO2, i.e., adsorbed Pt1 in Pt/CeO2 and square planar Pt1 in PtATCeO2, fabricated at 500 °C and by atom-trapping method at 800 °C, respectively. Adsorbed Pt1 in Pt/CeO2 is mobile with the in situ formation of few-atom Pt clusters during CO oxidation, contributing to high reactivity with near-zero reaction order in CO. In contrast, square planar Pt1 in PtATCeO2 is strongly anchored to the support during CO oxidation leading to relatively low reactivity with a positive reaction order in CO. Reduction of both Pt/CeO2 and PtATCeO2 in CO transforms Pt1 to Pt nanoparticles. However, both catalysts retain the memory of their initial Pt1 state after reoxidative treatments, which illustrates the importance of the initial single-atom structure in practical applications.

13.
Neurobiol Dis ; 48(3): 391-8, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22766032

RESUMEN

UNLABELLED: Genetic variants in UBQLN1 gene have been linked to neurodegeneration and mutations in UBQLN2 have recently been identified as a rare cause of amyotrophic lateral sclerosis (ALS). OBJECTIVE: To test if genetic variants in UBQLN1 are involved in ALS. METHODS: 102 and 94 unrelated patients with familial and sporadic forms of ALS were screened for UBQLN1 gene mutations. Single nucleotide variants were further screened in a larger set of sporadic ALS (SALS) patients and unrelated control subjects using high-throughput Taqman genotyping; variants were further assessed for novelty using the 1000Genomes and NHLBI databases. In vitro studies tested the effect of UBQLN1 variants on the ubiquitin-proteasome system (UPS). RESULTS: Only two UBQLN1 coding variants were detected in the familial and sporadic ALS DNA set; one, the missense mutation p.E54D, was identified in a single patient with atypical motor neuron disease consistent with Brown-Vialetto-Van Laere syndrome (BVVLS), for whom c20orf54 mutations had been excluded. Functional studies revealed that UBQLN1E54D protein forms cytosolic aggregates that contain mislocalized TDP-43 and impairs degradation of ubiquitinated proteins through the proteasome. CONCLUSIONS: Genetic variants in UBQLN1 are not commonly associated with ALS. A novel UBQLN1 mutation (E45D) detected in a patient with BVVLS altered nuclear TDP-43 localization in vitro, suggesting that UPS dysfunction may also underlie the pathogenesis of this condition.


Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Parálisis Bulbar Progresiva/genética , Proteínas Portadoras/genética , Proteínas de Ciclo Celular/genética , Pérdida Auditiva Sensorineural/genética , Proteínas Adaptadoras Transductoras de Señales , Proteínas Relacionadas con la Autofagia , Western Blotting , Análisis Mutacional de ADN , Femenino , Humanos , Inmunohistoquímica , Inmunoprecipitación , Masculino , Mutación , Polimorfismo de Nucleótido Simple , Transfección
14.
Hum Mol Genet ; 18(3): 454-62, 2009 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-18996915

RESUMEN

Angelman syndrome is a severe neurodevelopmental disorder mostly caused by loss-of-function mutations in the maternal allele of UBE3A, a gene that encodes an E3 ubiquitin ligase. Drosophila UBE3A (dUBE3A) is highly homologous to human UBE3A (hUBE3A) at the amino acid sequence level, suggesting their functional conservation. We generated dUBE3A-null mutant fly lines and found that dUBE3A is not essential for viability. However, loss of dUBE3A activity reduced dendritic branching of sensory neurons in the peripheral nervous system and slowed the growth of terminal dendritic fine processes. Several lines of evidence indicated that dUBE3A regulates dendritic morphogenesis in a cell autonomous manner. Moreover, overexpression of dUBE3A also decreased dendritic branching, suggesting that the proper level of dUBE3A is critically important for the normal dendritic patterning. These findings suggest that dendritic pathology may contribute to neurological deficits in patients with Angelman syndrome.


Asunto(s)
Dendritas/enzimología , Proteínas de Drosophila/metabolismo , Drosophila/enzimología , Ubiquitina-Proteína Ligasas/metabolismo , Síndrome de Angelman/enzimología , Síndrome de Angelman/genética , Animales , Dendritas/genética , Drosophila/genética , Drosophila/crecimiento & desarrollo , Proteínas de Drosophila/genética , Humanos , Morfogénesis , Sistema Nervioso Periférico/citología , Sistema Nervioso Periférico/enzimología , Sistema Nervioso Periférico/crecimiento & desarrollo , Células Receptoras Sensoriales/citología , Células Receptoras Sensoriales/enzimología , Ubiquitina-Proteína Ligasas/genética
15.
iScience ; 24(8): 102884, 2021 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-34401668

RESUMEN

Catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FAL) to furfuryl alcohol is recognized as one of the most versatile techniques for biomass valorization. However, the irreversible sintering of metal sites under the high-temperature reaction or during the coke removal regeneration process poses a serious concern. Herein, we present a silicalite-1-confined ultrasmall CuO structure (CuO@silicalite-1) and then compared its catalytic efficiency against conventional surface-supported CuO structure (CuO/silicalite-1) toward CTF of FAL with alcohols. Characterization results revealed that CuO nanoparticles encapsulated within the silicalite-1 matrix are ∼1.3 nm in size in CuO@silicalite-1, exhibiting better dispersion as compared to that in the CuO/silicalite-1. The CuO@silicalite-1, as a result, exhibited nearly 100-fold higher Cu-mass-based activity than the CuO/silicalite-1 counterpart. More importantly, the activity of the CuO@silicalite-1 catalyst can be regenerated via facile calcination to remove the surface-bound carbon deposits, unlike the CuO/silicalite-1 that suffered severe deactivation after use and cannot be effectively regenerated.

16.
Nanoscale ; 13(1): 206-217, 2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33325939

RESUMEN

Understanding how to control the nucleation and growth rates is crucial for designing nanoparticles with specific sizes and shapes. In this study, we show that the nucleation and growth rates are correlated with the thermodynamics of metal-ligand/solvent binding for the pre-reduction complex and the surface of the nanoparticle, respectively. To obtain these correlations, we measured the nucleation and growth rates by in situ small angle X-ray scattering during the synthesis of colloidal Pd nanoparticles in the presence of trioctylphosphine in solvents of varying coordinating ability. The results show that the nucleation rate decreased, while the growth rate increased in the following order, toluene, piperidine, 3,4-lutidine and pyridine, leading to a large increase in the final nanoparticle size (from 1.4 nm in toluene to 5.0 nm in pyridine). Using density functional theory (DFT), complemented by 31P nuclear magnetic resonance and X-ray absorption spectroscopy, we calculated the reduction Gibbs free energies of the solvent-dependent dominant pre-reduction complex and the solvent-nanoparticle binding energy. The results indicate that lower nucleation rates originate from solvent coordination which stabilizes the pre-reduction complex and increases its reduction free energy. At the same time, DFT calculations suggest that the solvent coordination affects the effective capping of the surface where stronger binding solvents slow the nanoparticle growth by lowering the number of active sites (not already bound by trioctylphosphine). The findings represent a promising advancement towards understanding the microscopic connection between the metal-ligand thermodynamic interactions and the kinetics of nucleation and growth to control the size of colloidal metal nanoparticles.

17.
Science ; 371(6529): 626-632, 2021 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-33542136

RESUMEN

Solvent molecules influence the reactions of molecular hydrogen and oxygen on palladium nanoparticles. Organic solvents activate to form reactive surface intermediates that mediate oxygen reduction through pathways distinct from reactions in pure water. Kinetic measurements and ab initio quantum chemical calculations indicate that methanol and water cocatalyze oxygen reduction by facilitating proton-electron transfer reactions. Methanol generates hydroxymethyl intermediates on palladium surfaces that efficiently transfer protons and electrons to oxygen to form hydrogen peroxide and formaldehyde. Formaldehyde subsequently oxidizes hydrogen to regenerate hydroxymethyl. Water, on the other hand, heterolytically oxidizes hydrogen to produce hydronium ions and electrons that reduce oxygen. These findings suggest that reactions of solvent molecules at solid-liquid interfaces can generate redox mediators in situ and provide opportunities to substantially increase rates and selectivities for catalytic reactions.

18.
Antioxidants (Basel) ; 10(6)2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-34203583

RESUMEN

Traumatic brain injury caused by blast is associated with long-term neuropathological changes including tau phosphorylation and pathology. In this study, we aimed to determine changes in initial tau phosphorylation after exposure to a single mild blast and the potential contribution of oxidative stress response pathways. C57BL/6 mice were exposed to a single blast overpressure (BOP) generated by a compressed gas-driven shock tube that recapitulates battlefield-relevant open-field BOP, and cortical tissues were harvested at different time points up to 24 h after blast for Western blot analysis. We found that BOP caused elevated tau phosphorylation at Ser202/Thr205 detected by the AT8 antibody at 1 h post-blast followed by tau phosphorylation at additional sites (Ser262 and Ser396/Ser404 detected by PHF1 antibody) and conformational changes detected by Alz50 antibody. BOP also induced acute oxidative damage at 1 h post-blast and gradually declined overtime. Interestingly, Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) were acutely activated in a similar temporal pattern as the rise and fall in oxidative stress after blast, with p38 showing a similar trend. However, glycogen synthase kinase-3 ß (GSK3ß) was inhibited at 1 h and remained inhibited for 24 h post blast. These results suggested that mitogen-activated protein kinases (MAPKs) but not GSK3ß are likely involved in mediating the effects of oxidative stress on the initial increase of tau phosphorylation following a single mild blast.

19.
Sci Rep ; 10(1): 14221, 2020 08 26.
Artículo en Inglés | MEDLINE | ID: mdl-32848189

RESUMEN

Mutations in CHMP2B, encoding a protein in the endosomal sorting complexes required for transport (ESCRT) machinery, causes frontotemporal dementia linked to chromosome 3 (FTD3). FTD, the second most common form of pre-senile dementia, can also be caused by genetic mutations in other genes, including TANK-binding kinase 1 (TBK1). How FTD-causing disease genes interact is largely unknown. We found that partial loss function of Ik2, the fly homologue of TBK1 also known as I-kappaB kinase ε (IKKε), enhanced the toxicity of mutant CHMP2B in the fly eye and that Ik2 overexpression suppressed the effect of mutant CHMP2B in neurons. Partial loss of function of Spn-F, a downstream phosphorylation target of Ik2, greatly enhanced the mutant CHMP2B phenotype. An interactome analysis to understand cellular processes regulated by Spn-F identified a network of interacting proteins including Spn-F, Ik2, dynein light chain, and Hook, an adaptor protein in early endosome transport. Partial loss of function of dynein light chain or Hook also enhanced mutant CHMP2B toxicity. These findings identify several evolutionarily conserved genes, including ik2/TBK1, cut up (encoding dynein light chain) and hook, as genetic modifiers of FTD3-associated mutant CHMP2B toxicity and implicate early endosome transport as a potential contributing pathway in FTD.


Asunto(s)
Proteínas de Drosophila/genética , Endosomas/fisiología , Demencia Frontotemporal/genética , Proteínas de Transporte Vesicular/genética , Animales , Modelos Animales de Enfermedad , Drosophila , Dineínas/genética , Quinasa I-kappa B/genética , Proteínas Asociadas a Microtúbulos/genética
20.
ChemSusChem ; 13(18): 4922-4928, 2020 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-32671910

RESUMEN

Catalytic deoxygenation of even-numbered fatty acids into odd-chain linear α-olefins (LAOs) has emerged as a complementary strategy to oligomerization of ethylene, which only affords even-chain LAOs. Although enzymes and homogeneous catalysts have shown promising potential for this application, industrial production of LAOs through these catalytic systems is still very difficult to accomplish to date. A recent breakthrough involves the use of an expensive noble-metal catalyst, Pd/C, through a phosphine ligands-assisted method for LAOs production from fatty acid conversion. This study presents a unique, cost-friendly, non-noble bimetallic NiFe/C catalyst for highly selective LAOs production from fatty acids through decarbonylative dehydration. In the presence of acetic anhydride and phosphine ligand, a remarkable improvement in the yield of 1-heptadecene from the conversion of stearic acid was found over the supported bimetallic catalyst (NiFe/C) as compared to corresponding monometallic counterparts (Ni/C and Fe/C). Through optimization of the reaction conditions, a 70.1 % heptadecene yield with selectivity to 1-heptadecene as high as 92.8 % could be achieved over the bimetallic catalyst at just 190 °C. This unique bimetallic NiFe/C catalyst is composed of NiFe alloy in the material bulk phase and a surface mixture of NiFe alloy and oxidized NiFeδ+ species, which offer a synergized contribution towards decarbonylative dehydration of stearic acid for 1-heptadecene production.

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